Artículos de revistas: "Manganite X-rays"

1

Akram, Khush Bakhat, M. S. Dar, Faheem-ul-Hassan y M. Anis-ur-Rehman. "Synthesis and AC Electrical Characterization of Co Doped Bismuth Manganite Nanoparticles". Key Engineering Materials 510-511 (mayo de 2012): 527–31. http://dx.doi.org/10.4028/www.scientific.net/kem.510-511.527.

Texto completo

Resumen

Multiferroic bismuth manganites (BiMnO3) possess both ferromagnetic and ferroelectric properties. Their electrical properties can be controlled by doping for useful applications. In this work single-phase cobalt doped bismuth manganite nanoparticles having general formula BiMn1-xCoxO3(x=0, 0.2, 0.4, 0.6) were synthesized by co-precipitation method. Structural properties like lattice parameters and crystallite size of samples were determined by the data obtained by X-rays diffraction. The dielectric constant (ε) and dielectric loss tangent (tanδ) of samples were investigated as a function of frequency from 20Hz-3MHz using ac measurement data. For all the compositions dielectric constant was decreased with increasing frequency, however it increased with the increase in cobalt content. However cobalt addition causes a decrease in loss tangent as compared to pure BiMnO3composition. The origin of this behavior is discussed in terms of Maxwell-Wagner and Koops model. Substitution of Mn with Co, in BiMnO3-based compounds is supposed to cause better properties in terms of tangent loss.

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

WILKINS, STUART B., PETER D. HATTON, KLAUS-DIETER LISS, M. OHLER, T. KATSUFUJI y S. W. CHEONG. "HIGH-RESOLUTION HIGH ENERGY X-RAY DIFFRACTION STUDIES OF CHARGE ORDERING IN CMR MANGANITES AND NICKELATES". International Journal of Modern Physics B 14, n.º 29n31 (20 de diciembre de 2000): 3753–58. http://dx.doi.org/10.1142/s0217979200004301.

Texto completo

Resumen

High-resolution, high-energy, X-ray diffraction results are presented for the study of weak charge ordering phenomenon. By utilizing X-rays in the 100 keV region the dramatic increase in the penetration depth allows for both bulk-sensitive and high-resolution measurements to be made. The strontium doped La 2 NiO 4 system is a prototypical system in the understanding of strong electron-phonon coupling, and the resultant effects on material properties. At doping levels of 1/3 and 1/2 commensurate charge modulations are observed indicating real-space charge stripes. We have measured the correlation lengths of these charge stripes using both 100 keV X-rays and 8.3 keV X-rays. In comparing our results we have observed that the charge stripes appear to be well correlated in the near-surface region with correlation lengths ξ≈2400Å. However, our bulk sensitive measurements show that the charge stripes appear in a possible stripe glass phase with a correlation length of only ξ≈300Å. Our measurements on the 3D charge order manganite system Nd 0.5 Sr 0.5 MnO 3 show that the charge ordering appears to be well correlated in the bulk of the sample in contrast to our nickelate results.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Adeoye, Akintola Ojo, Najime Tavershima, Danladi Bello Abubakar, Ogunleye Paul Olusegun y Abubakar Ismail Yusuf. "Petrochemical Features of Manganese Nodules in Madaka (Sheet 142) SE and Part of Kwana - Bala (Sheet 142) NE, Nigeria". Sumerianz Journal of Scientific Research, n.º 43 (24 de julio de 2021): 52–59. http://dx.doi.org/10.47752/sjsr.43.52.59.

Texto completo

Resumen

Manganese nodule occurs in Madaka (Sheet 142) SE and part of Kwana - Bala (Sheet 142) NE, Nigeria. Four (4) samples of manganese nodules were analyzed petrochemical using X-ray diffractometry (XRD), reflected light microscopy, Electron probe micro analysis (EPMA), Atomic absorption spectrophotometer (AAS). XRD reveals sphalerite, manganates and ilmenite as major minerals in the nodules. Accessory minerals are siderite and rutile. Chemical study of the manganese nodules from Madaka and Kwana - Bala reveals that Mn-, Fe-, Co-, Ni-, and Cu-, minerals (including native elements and sulfides) commonly occur in the samples. Also, the results indicate that increased in Mn relative to the manganite content (10AO- plus 7AO), led to increase in Ni and Cu recovery. However, slightly greater amounts by weight of Ni and Cu were dissolved from the manganites than from Mn. This followed from the much higher Ni and Cu contents of manganites relative to Mn. The exploration for Ni and Cu from nodules on assay criterion was inadequate; the sphalerite Mn02 phase structure would also be a necessary criterion. It was suggested that nodules could be processed upon beneficiation for Ni and Cu contents for a future time relative to the original processing. It was thus proposed that Ni and Cu could be produced from manganese nodules in the study area.

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Kuma, Kenshi, Akira Usui, William Paplawsky, Benjamin Gedulin y Gustaf Arrhenius. "Crystal structures of synthetic 7 Å and 10 Å manganates substituted by mono- and divalent cations". Mineralogical Magazine 58, n.º 392 (septiembre de 1994): 425–47. http://dx.doi.org/10.1180/minmag.1994.058.392.08.

Texto completo

Resumen

AbstractThe crystal structures of synthetic 7 Å and 10 Å manganates, synthetic birnessite and buserite, substituted by mono- and divalent cations were investigated by X-ray and electron diffractions. The monoclinic unit cell parameters of the subcell of lithium 7 Å manganate, which is one of the best ordered manganates, were obtained by computing the X-ray powder diffraction data: a = 5.152 Å, b = 2.845 Å, c = 7.196 Å, β = 103.08°. On the basis of the indices obtained by computing the X-ray diffraction data of Li 7 Å manganate, monovalent Na, K and Cs and divalent Be, Sr and Ba 7 Å manganates were interpreted as the same monoclinic structure with β = 100–103° as that of Li 7 Å manganate, from their X-ray diffraction data. In addition, divalent Mg, Ca and Ni 10 Å manganates were also interpreted as the same monoclinic crystal system with β = 90–94° The unit cell parameters, especially a, c and β, change possibly with the type of substituent cation probably because of the different ionic radius, hydration energy and molar ratio of substituent cation to manganese. However, these diffraction data, except for those of Sr and Ba 7 Å and Ca and Ni 10 Å manganates, reveal only some parts of the host manganese structure with the edge-shared [MnO6] octahedral layer. On the other hand, one of the superlattice reflections observed in the electron diffractions was found in the X-ray diffraction lines for heavier divalent cations Sr and Ba 7 Å and Ca and Ni 10 Å manganates. The reflection presumably results from the substituent cation position in the interlayer which is associated with the vacancies in the edge-shared [MnO6] layer and indicates that the essential vacancies are linearly arranged parallel to the b-axis. Furthermore, the characteristic superlattice reflection patterns for several cations, Li, Mg, Ca, Sr, Ba and Ni, manganates were interpreted that the substituent cations are regularly distributed in the interlayer according to the exchange percentage of substituent cation to Na+. In contrast, the streaking in the a-direction observed strongly in the electron diffractions for heavier monovalent cations, K and Cs, manganates probably results from the disordering of their cations in the a-direction in the interlayer.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Kasenov, B. K. "SYNTHESIS AND X-RAY INVESTIGATION OF NOVEL NANOSTRUCTURED COPPER-ZINC MANGANITES OF LANTHANUM AND ALKALI METALS". Eurasian Physical Technical Journal 18, n.º 1 (30 de marzo de 2021): 29–33. http://dx.doi.org/10.31489/2021no1/29-33.

Texto completo

Resumen

The aim of this work is to synthesize new nanostructured copper-zinc lanthanum and alkaline metal manganites. Polycrystalline copper-zinc manganites of lanthanum and alkali metals were synthesized by the method of ceramic technology from lanthanum (III), copper (II), zinc (II), manganese (III) oxides, and lithium, sodium, and potassium carbonates in the range of 800-1200 oC. Nanostructured particles were obtained by grinding the synthesized polycrystalline compounds at the «MM301» vibration mill of «Retsch» (Germany). By indexing X-ray images of nanostructured copper-zinc lanthanum and alkaline metal manganites, it was found that they crystallize in cubic syngony. Their lattice parameters are determined. There is a pattern in the change of the lattice parameters from the ionic radii of alkaline metals.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Hashemi, T. y A. W. Brinkman. "X-ray photoelectron spectroscopy of nickel manganese oxide thermistors". Journal of Materials Research 7, n.º 5 (mayo de 1992): 1278–82. http://dx.doi.org/10.1557/jmr.1992.1278.

Texto completo

Resumen

The major problem in the NiMn2O4 system has been the determination of the valencies and the cation distribution between the two sublattices of the inverse spinel structure, in which both manganese and nickel can adopt more than one valence state. X-ray photoelectron spectroscopy (XPS) was used to elucidate the valence distribution of the manganese and nickel ions. The results showed that identification of the three Mn and two Ni species in the nickel manganite phase is possible, enabling the validity of crystal structure configurations, proposed in the literature, to be assessed. A small amount of copper, added as CuO to the system, was found to be present in both monovalent and divalent states, the Cu+ ions inducing the creation of the large amount of tetravalent Mn observed. This led to a larger number of sites for electron hopping, the mechanism of conduction, and consequently the electrical conductivity of the Cu doped material is much higher than the undoped NiMn2O4.

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Zhu, J. L., R. C. Yu, F. Y. Li, C. Q. Jin y Z. Zhang. "Study of phase components of La1.5Ca1.5Mn2O7". Journal of Materials Research 16, n.º 7 (julio de 2001): 2027–31. http://dx.doi.org/10.1557/jmr.2001.0277.

Texto completo

Resumen

The manganate with nominal composition La1.5Ca1.5Mn2O7, which is regarded as a single-phase compound with layered perovskite structure in the literature, was prepared using a standard ceramic process. The structures and morphology of the manganate were investigated by x-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy, and energy-dispersive x-ray microanalysis. However, no direct evidence of layered Sr3Ti2O7-type structure was observed in TEM experiments; instead, we observed multiphase mixtures of an orthorhombically distorted perovskite phase as majority and cubic perovskite phase as minority, as well as a small amount of calcium oxide. The measured magnetic and transport properties of this manganate arise mainly from the presence of hole-doped multiphase perovskite manganates. These physical properties demonstrated again the correctness of our phase component analysis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Battault, T., R. Legros y A. Rousset. "Aging of iron manganite negative temperature coefficient thermistors". Journal of Materials Research 13, n.º 5 (mayo de 1998): 1238–42. http://dx.doi.org/10.1557/jmr.1998.0176.

Texto completo

Resumen

“Aging,” defined as the drift of resistance with temperature after 1000 h, was investigated for iron manganite temperature coefficient thermistors. For these devices, aging is relatively large, about 10%. The cationic distributions before and after aging were determined by Mössbauer spectroscopy. These distributions explain all the x-ray diffraction and correlated electrical data. The origin of the aging observed on iron manganites thermistors has been identified. It is due to the migration of Fe3+ ions from tetrahedral to octahedral sites of the spinel structure in order to reach a structural equilibrium.

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Min, Soyoung y Yeongkyoo Kim. "Physicochemical Characteristics of the Birnessite and Todorokite Synthesized Using Various Methods". Minerals 10, n.º 10 (5 de octubre de 2020): 884. http://dx.doi.org/10.3390/min10100884.

Texto completo

Resumen

The synthesis methods used to produce todorokite (10 Å manganate, OMS-1) and birnessite (7 Å manganate), which are abundant in marine manganese nodules, have been studied to confirm whether pure mineral phases can be obtained and to compare their physicochemical characteristics. The physicochemical characteristics of todorokite and its precursor Na–birnessite can vary widely based on the precursors used during their synthesis. Birnessite can be synthesized via three mechanisms, i.e., the oxidation of Mn2+, a redox reaction between Mn2+ and MnO4−, or the reduction of MnO4−. Herein, four precursors are used to synthesize birnessite using different methods before being transformed into todorokite. The characteristics of the birnessite and todorokite synthesized using different methods are investigated via X-ray diffraction (XRD), chemical analysis, Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (SEM). Based on the method used, birnessite and todorokite exhibit distinct physicochemical features, including crystallinity, crystal structure, specific surface area, oxidation state of manganese, thermal stability, and morphology. Thus, the characteristics of birnessite and todorokite are closely correlated, indicating the importance of designing suitable methods to synthesize them for specific applications.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

ASOKAN, K., K. V. R. RAO, J. C. JAN, J. W. CHIOU, W. F. PONG, RAVI KUMAR, SHAHID HUSAIN y J. P. SRIVASTAVA. "ELECTRONIC STRUCTURES OF La0.7Ca0.3MnO3 AND La0.7Ce0.3MnO3 BY X-RAY ABSORPTION SPECTROSCOPY". Surface Review and Letters 09, n.º 02 (abril de 2002): 1053–57. http://dx.doi.org/10.1142/s0218625x02003330.

Texto completo

Resumen

Electronic structures of hole-doped and electron hole-doped manganites, La 0.7 Ca 0.3 MnO 3 and La 0.7 Ce 0.3 MnO 3, have been elucidated by X-ray absorption near-edge structure (XANES) spectra of O K- and Mn L3,2-edges. In the electron-doped system, La 0.7 Ce 0.3 MnO 3, the spectral features of O K-edge spectra are shifted by ~ 1 eV towards the higher energy side and reduction of Mn valency from 4+ and 3+ to 3+ and 2+ is expected when compared to hole-doped manganite. The XANES of Ce M5,4-edges indicates a tetravalent state for Ce, similar to that in CeO 2. Ce 4+ is incorporated into the lattice of LaMnO 3, resulting in the modification of MnO 6 octahedra and also indicating strong hybridization of Ce 5d and/or Ce 4f states with O 2p states.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Lim, Kean Pah, Lik Nguong Lau, Mohd Mustafa Awang Kechik, Soo Kien Chen, Shaari Abdul Halim y Nurul Suhada Badron. "Investigation of Nano-Sized Al₂O₃ on Pr-Sr-Mn-O Composites: Structural, Microstructural and Magnetic Properties". Solid State Phenomena 307 (julio de 2020): 3–8. http://dx.doi.org/10.4028/www.scientific.net/ssp.307.3.

Texto completo

Resumen

Perovskite manganites have always been the research interest attributed to its intriguing colossal magnetoresistive (CMR) properties. Incorporation of an insulating secondary phase into the manganite composites has proven as an effective measure to enhance the low field magnetoresistance (LFMR). This paper reports the structural, microstructural and magnetic properties of (1-x) Pr0.7Sr0.3MnO3 (PSMO): x Al2O3 composites synthesized by the solid-state reaction method. Different compositions of nano-sized Al2O3 (x = 0.00, 0.05, 0.10, 0.15 and 0.20) were appended into the samples to investigate its effect on the physical properties. X-ray diffraction patterns show all samples exhibit polycrystalline PSMO as the major phase and strong orientation along (121) direction throughout the series. The crystal structural parameter is presented by Rietveld refinement. Nano-sized of Al2O3 has distorted the pure PSMO as changes have been observed in bond length and bond angle observed. Surface roughness and particle size show the increment along with increasing Al2O3 composition from the atomic force microscope (AFM) analysis. All samples possess the narrow hysteresis loop with weak ferromagnetic nature. The PSMO: Al2O3 presented in this study is a promising manganite composite which can be utilized in the magnetic sensor applications.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Faruqi, Muhammad Umar, Arif Tjahjono y Sitti Ahmiatri Saptari. "Analisis Struktur Kristal dan Sifat Kemagnetan Material Komposit Perovskite Manganit Nd0,6Sr0,4MnO3/ZnO". Al-Fiziya: Journal of Materials Science, Geophysics, Instrumentation and Theoretical Physics 3, n.º 1 (4 de agosto de 2020): 1–8. http://dx.doi.org/10.15408/fiziya.v3i1.16158.

Texto completo

Resumen

AbstrakPerovskite manganit merupakan salah satu rekayasa material yang dapat menghasilkan perubahan fenomena fisika. Telah berhasil dibuat material berbasis perovskite manganit Nd0,6Sr0,4MnO3 menggunakan metode sol-gel¬ dan dikompositkan dengan ZnO (Nd0,6Sr0,4MnO3)1-x/(ZnO)x (x = 0; 0,3; 0,5; 0,7). Hasil pengujian X-Ray Diffraction menunjukkan sampel Nd0,6Sr0,4MnO3 berstruktur tunggal ortorombik dan sampel ZnO pada (Nd0,6Sr0,4MnO3)0,5/(ZnO)0,5 berstruktur heksagonal tunggal. Hasil pengujian Field Emission Scanning Electron Microscope menunjukkan sampel telah homogen dengan rata-rata ukuran butir 0,188 μm. Hasil pengujian Vibrating Sample Magnetometer menunjukkan sampel (Nd0,6Sr0,4MnO3)0,5/(ZnO)0,5 bersifat paramagnetik dan mengalami penurunan sifat magnetik juga suseptibilitas seiring dengan penambahan konsentrasi material ZnO. AbstractPerovskite manganite is one of the manipulation materials that can produce changes in physical phenomena. Perovskite material Nd0,6Sr0,4MnO3 has been made with the sol-gel method and then composites with ZnO (Nd0.6Sr0.4MnO3)1-x/(ZnO)x (x = 0; 0.3; 0.5, 0, 7). The results of the X-Ray Diffraction characterization test showed samples of Nd0,6Sr0,4MnO3 and ZnO each with a single orthorhombic phase with a Pnma space group and a single hexagonal with a P63mc space group. The results of the Field Emission Scanning Electron Microscope characterization test showed that the samples were homogeneous with an average grain size of 0,188 μm. Vibrating Sample Magnetometer characterization test results show composite material (Nd0,6Sr0,4MnO3)1-x/(ZnO)x are paramagnetic and the increasing composition of ZnO material decreases the magnetization and susceptibility value of sample

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Lee, Sun Hee, Dae Hoon Park, Seong-Ju Hwang y Jin-Ho Choy. "Effect of Copper Doping on the Crystal Structure and Morphology of 1D Nanostructured Manganese Oxides". Journal of Nanoscience and Nanotechnology 7, n.º 11 (1 de noviembre de 2007): 4029–32. http://dx.doi.org/10.1166/jnn.2007.080.

Texto completo

Resumen

We have tried to control the aspect ratio and physicochemical properties of 1D nanostructured manganese oxides through copper doping. Copper-doped manganese oxide nanostructures have been synthesized by one-pot hydrothermal treatment for the mixed solution of permanganate anions and copper cations. According to powder X-ray diffraction and electron microscopic analyses, all the present materials commonly crystallize with α-MnO2-type structure but their aspect ratio decreases significantly with increasing the content of copper. Such a variation of crystallite dimension is attributable to the limitation of crystal growth by the incorporation of copper ions. X-ray absorption spectroscopic studies at Mn K- and Cu K-edges clearly demonstrate that the average oxidation state of manganese ions is increased by the substitution of divalent copper ions. Electrochemical measurements reveal the improvement of the electrode performance of nanostructured manganate upon copper doping, which can be interpreted as a result of the decrease of aspect ratio and the increase of Mn valence state. From the present experimental findings, it becomes certain that the present Cu doping method can provide an effective way of controlling the crystal dimension and electrochemical property of 1D nanostructured manganese oxide.

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Theingi, Mya, Ji Ma, Hui Zhang, Xiang Gao, Jian Hong Yi y Qing Ming Chen. "Study of Structural and Electrical Transport Properties of Polycrystalline La_1-XCa_XMnO₃ (x=0.33, 0.5 and 0.9) Prepared by a Co-Precipitation Method". Advanced Materials Research 652-654 (enero de 2013): 576–80. http://dx.doi.org/10.4028/www.scientific.net/amr.652-654.576.

Texto completo

Resumen

Manganite perovskite La1-xCaxMnO3(x=0.33, 0.5 and 0.9) have been prepared by chemical co-precipitation method. Ammonium carbonate was used to coprecipitate lanthanum, calcium and manganese ions as carbonates under basic condition. This precursor on calcining at 900°C yields La-Ca-Mn-O perovskite phase. Follow by sintering at 1200°C after the powders were pressed into pellets gave La1-xCaxMnO3(LCMO) polycrystalline ceramics. The crystal phases of the resulting powders and ceramics were examined by X-ray diffraction (XRD) technique. The morphology of the powders was observed by scanning electron microscopy (SEM) and electrical transport properties of ceramics were measured by conventional four-point probe technique.

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Galakhov, Vadim R. "Application of 3s X-Ray Photoelectron Spectra for Determination of Charge States and Magnetic Moments of 3d Ions in Oxides". Solid State Phenomena 168-169 (diciembre de 2010): 453–56. http://dx.doi.org/10.4028/www.scientific.net/ssp.168-169.453.

Texto completo

Resumen

There are presented core-level 3s X-ray photoelectron spectra of some 3d oxides. The possibility to extract additional information on intra- and interatomic exchange effects from 3s X-ray photoelectron spectra is demonstrated. The results pointed to the possibility of using X-ray photoelectron 3s spectra for estimation of local spin magnetic moments localized on 3d elements in manganese and iron oxides. We have found that for doped manganites, the Mn formal valency from 3+ to 3.3+ is not accompanied by any decrease in the Mn 3s splitting. This fact can be explained by the holes in the O 2p states (d4L ground-state configuration). For Cu, Ni, and Co oxides, the charge-transfer effect dominates the multiplet effect in the 3s spectra which allows to estimate the occupancy of 3d states.

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Rykov, A. I., M. Seto, Y. Ueda y K. Nomura. "Anisotropic phonon density of states: the application of Rietveld and Mössbauer texture analysis in aligned powders". Journal of Applied Crystallography 42, n.º 3 (28 de abril de 2009): 496–501. http://dx.doi.org/10.1107/s0021889809010747.

Texto completo

Resumen

Since it is not always feasible to synthesize single crystals of novel materials, the orientation of layered polycrystals has become an attractive basis for studying the angular dependence of inelastic scattering of X-rays or neutrons. Utilizing Rietveld analysis, the anisotropic properties of layered structures in novel manganites and cuprates have been studied with oriented powders instead of single crystals. The phonon density of states (DOS) and atomic thermal displacement are anisotropic in theA-site-ordered manganites LnBaMn2Oyfor the seriesy= 5 andy= 6 (Ln = Y, La, Sm and Gd). This article establishes the angular dependence of the DOS on texture of arbitrary strength, links the textures observed by X-ray and γ-ray techniques, and solves the problem of disentanglement of the Goldanskii–Karyagin effect and texture in Mössbauer spectra.

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Sekhar, M. Chandra, K. Padmavathi, J. G. Park y P. Venugopal Reddy. "Elastic Behavior of YMnO3 and ErMnO3 Manganites". Modern Physics Letters B 17, n.º 20n21 (10 de septiembre de 2003): 1119–25. http://dx.doi.org/10.1142/s0217984903006025.

Texto completo

Resumen

The manganite oxides, YMnO 3 and ErMnO 3 having hexagonal structures were prepared by the solid state reaction method. After characterizing these materials by studying their various physical properties such as lattice parameters, X-ray density, bulk density etc., ultrasonic velocity measurements were carried out over a temperature range 80–300 K to investigate their elastic behavior. As the materials are porous, the measured elastic moduli were corrected to zero porosity. Using the room temperature elastic moduli, Debye temperature values of both the manganites have also been obtained. Surprisingly it has been found that the Young's moduli of both the materials increase continuously with decreasing temperature. A qualitative explanation for the observed behavior is offered.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Abou-Sekkina, Morsi, Fawaz Saad, Fouad El-Metwaly y Abdalla Khedr. "Synthesis, characterization, DC-electrical conductivity and γ-ray effect on Ag1+, Y3+ double doped nano lithium manganates (LiMn2−2x AgxYxO4) for rechargeable batteries". Materials Science-Poland 32, n.º 3 (1 de septiembre de 2014): 315–23. http://dx.doi.org/10.2478/s13536-014-0205-1.

Texto completo

Resumen

AbstractPristine lithium manganate (LiMn2O4) and Ag1+, Y3+ double doped nano lithium manganate [LiMn2−2x AgxYxO4, (x = 0.025, 0.05)] spinels were synthesized via a coprecipitation method for rechargeable batteries applications. The synthesized LiMn1.9Ag0.05Y0.05O4 was exposed to different doses of γ-irradiation (10 and 30 kGy). The resulting spinel products were characterized by using thermogravimetric and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX), electronic (UV-Vis) and electron spin resonance (ESR) spectra. LiMn2O4 exhibited a discharge capacity of 124 mAhg−1 while LiMn1.9Ag0.05Y0.05O4 had discharge capacities of 129 and 137 mAhg−1 for non irradiated and γ-irradiated (30 kGy) samples, respectively. The effects of the dopant cations and γ-irradiation on the discharge capacity and DC-electrical conductivity of some synthesized spinels were studied.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Ye, Zi, Jun Xie y Xing Hua Xie. "Measuring of Nanometer Oxide Powders". Advanced Materials Research 503-504 (abril de 2012): 1416–19. http://dx.doi.org/10.4028/www.scientific.net/amr.503-504.1416.

Texto completo

Resumen

Lithium manganese oxides with a fine spherical morphology different from that of the normal composite oxides are formed after detonation wave treatment due to the very high quenching rate. Free metal atoms are first released with the decomposition of explosives, and then theses metal and oxygen atoms are rearranged, coagulated and finally crystallized into lithium manganate during the expansion of detonation process. The growth of lithium manganate via detonation reaction was investigated with respect to the presence of an energetic precursor, such as the metallic nitrate and the degree of confinement of the explosive charge. The detonation products were characterized by scanning electron microscopy. Powder X-ray diffraction and transmission electron microscopy were used to characterize the products. Lithium manganate with spherical morphology and more uniform secondary particles, with smaller primary particles of diameters from 10 to 20 nm and a variety of morphologies were found.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Fujioka, Yukari, Johannes Frantti, Sven C. Vogel, Jian Zhong Zhang, Zhi Jun Lin, Helmut Reiche, Adrian Losko y Luke L. Daemen. "Neutron Powder Diffraction Study of the Effect of Mn-Doping on SrTiO₃". Materials Science Forum 700 (septiembre de 2011): 28–32. http://dx.doi.org/10.4028/www.scientific.net/msf.700.28.

Texto completo

Resumen

The effect of manganese doping on the magnetic and structural properties of strontiumtitanate (SrTiO3) was studied. Neutron powder diffraction, x-ray diffraction, magneticmeasurements, scanning electron microscopy and energy dispersive spectroscopy of x-rays wereutilized. Air-sintered Sr(MnxTi1-x)O3 (SMT) with x = 0:02 and x = 0:05 were homogeneoussingle phase orthorhombic (space group Pbnm) perovskite samples. The symmetry was orthorhombicalready at room temperature, and no symmetry change was observed down to 11K. An anomaly in the magnetic susceptibility was observed in x = 0:02 sample at 75 K. Incontrast to earlier reports, no ferromagnetism was observed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

HATTON, P. D., S. B. WILKINS, P. D. SPENCER, D. MANNIX, S. D. BROWN, T. D'ALMEIDAHATTON y S. W. CHEONG. "CHARGE AND ORBITAL ORDER IN THE ELECTRON DOPED MAGNANITE (Bi,Ca)MnO3". International Journal of Modern Physics B 16, n.º 11n12 (20 de mayo de 2002): 1661–66. http://dx.doi.org/10.1142/s0217979202011470.

Texto completo

Resumen

The interplay between charge, spin and orbital degrees of freedom in transition metal oxides has been a matter of much interest in recent years. In this paper we present X-ray scattering results of charge and orbital ordering in the electron doped manganite Bi 0.24 Ca 0.76 MnO 3. Using High Energy X-ray Scattering (HEXS) the charge ordering, structural modulation due to the Jahn–Teller ordering and the harmonic of the structural modulation have been measured. The superlattice reflections due to the Jahn–Teller ordering are found to maximise in intensity at the Neél point. We have confirmed using resonant X-ray scattering at the K-edge of manganese and the Anisotropic Tensor of Susceptibility technique (ATS) that superlattice reflections occurring at a modulation wavevector of (0.5, 0, 0) are due to charge ordering in a Mn 3+/ Mn 4+ ordering pattern. In addition superlattice reflections corresponding to the orbital order were measured at a modulation wavevector of (0.25, 0, 0). The temperature dependence of both the Jahn–Teller structural distortion peak (1.75, 2, 0) and the charge ordering peak (3 0 0) were observed to behave identically, gradually increasing with decreasing temperature.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Grenier, S., K. J. Thomas, V. Kiryukhin y J. P. Hill. "Resonant X-ray diffraction on manganites". Acta Crystallographica Section A Foundations of Crystallography 60, a1 (26 de agosto de 2004): s58. http://dx.doi.org/10.1107/s010876730409885x.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Mera-Córdoba, Jenny Alejandra, María Angélica Mera-Córdoba y Carlos Arturo Córdoba-Barahona. "Spin Coating technique for obtaining nanometric thin films in the system La0.7Sr0.3MnO3". Revista Facultad de Ingeniería 26, n.º 44 (25 de enero de 2017): 123. http://dx.doi.org/10.19053/01211129.v26.n44.2017.5783.

Texto completo

Resumen

Manganite in the La0.7Sr0.3MnO3 system is of great interest due to its potential application in fuel cells, information storage, magnetic field sensors, non-volatile memories, oxygen sensors, and catalysts in the oxidation of light hydrocarbons. Given the scientific relevance of this material, this study describes the procedure to synthesize and characterize thin films of La0.7Sr0.3MnO3. Manganites were synthesized by means of the Pechini method, and deposited on strontium titanate substrates using spin-coating. Both the crystallinity of the films and their phases were studied with X-ray diffraction (XRD), finding that the films are polycrystalline and have a simple cubic structure with a lattice constant a=3.8653 ± 0.066 Ǻ. Scanning electron microscopy (SEM) showed a uniform surface with good morphological features, and the spectrum resulted from the Energy Dispersive X-Ray Spectroscopy (EDS) analysis over the same film was consistent with the molar ratio of the perovskite. Samples of 2, 4, and 6 layers were synthesized, obtaining thicknesses of 75.10 ± 0.01, 75.02 ± 0.01 and 74.07 ± 0.08 nm per monolayer. The results indicate that this method is useful to synthesize films of high crystalline quality and nanometric size.

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

NAVASERY, M., S. A. HALIM, K. P. LIM, S. K. CHEN, A. S. ROSLAN y R. ABD-SHUKOR. "STRUCTURE, ELECTRICAL TRANSPORT AND MAGNETO-RESISTANCE PROPERTIES OFLa5/8Ca3/8MnO3MANGANITE SYNTHESIZED WITH DIFFERENT MANGANESE PRECURSORS". Modern Physics Letters B 26, n.º 06 (10 de marzo de 2012): 1150039. http://dx.doi.org/10.1142/s0217984911500394.

Texto completo

Resumen

We synthesized the polycrystalline manganite of La5/8Ca3/8MnO3with three different manganese routes prepared through a solid state reaction method. The effects of the manganese route selection on the structure, electrical transport and magneto-transport properties were examined in this study. The samples were characterized using X-ray diffraction (XRD) and SEM to identify their structure and morphology. XRD analysis confirmed that all samples were in single phase with orthorhombic structure and belonged to the Pnma space group. The average grain sized samples with manganese route of Mn2O3and MnCO3had a grain size of 1.2–8.7 μm and 2–7.5 μm, respectively. For the MnO2route, the sample had a small melt-like shape with higher porosity. The metal–insulator transition temperature, TMI, for LCMO ( Mn2O3), LCMO ( MnO2) and LCMO ( MnCO3) samples were 270 K, 266 K and 258 K, respectively. All the samples showed negative magneto-resistance with significant increase in value near the TMItemperature. The highest CMR (colossal magneto-resistance) ratio was found in LCMO ( Mn2O3), -22.06% at 270 K, followed by -16.69% for LCMO ( MnO2) at 80 K, and 15.2% for LCMO ( MnCO3) at 100 K in a 1 T magnetic field.

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Scherrer, René y Vivion E. Shull. "Microincineration and elemental X-ray microanalysis of single Bacillus cereus T spores". Canadian Journal of Microbiology 33, n.º 4 (1 de abril de 1987): 304–13. http://dx.doi.org/10.1139/m87-052.

Texto completo

Resumen

Single whole spores of bacillus cereus T were analyzed by scanning electron microscopy and electron microprobe X-ray microanalysis before and after high-temperature (600 °C) ashing in air. High-temperature ashing consisted of a centripetal oxidation of the spore surface combined with pyrolysis of the spore's interior. Ashing of single spores produced a compact central ash particle, mimicking the much larger unashed spore body in outline but containing craterlike microregions, and a peripheral thin ash film. Ashing mostly eliminated the spore's organic matrix; however, ash residues still gave residual carbon-characteristic X-ray counts. Ashing of single spores produced a two-, five-, and six-fold increase of potassium, magnesium, and calcium X-ray intensities, respectively. Iron, although low in actual counts, became detectable after ashing. Phosphorus characteristic X-rays were decreased by 41% after ashing, while volatilization lowered sodium and manganese X-ray intensities by over 80%. High-temperature ashing enhanced element-characteristic X-ray intensities of the non-volatilizable mineral(ized) elements of spores by compacting them into ash residues, more so than by simply abolishing their organic matrix. Microincineration appears a generally useful preconcentration technique for elemental detection and localization in X-ray microanalysis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Zheng, Kai, Tong-chao Zhang, Pin Lin, Yu-hua Han, Hong-yi Li, Ren-jie Ji y Hai-yun Zhang. "4-Nitroaniline Degradation by TiO2Catalyst Doping with Manganese". Journal of Chemistry 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/382376.

Texto completo

Resumen

Stainless steel anode covered with layer film of TiO2doped with manganese was utilized to decompose 4-nitroaniline in rectangular borosilicate glass reactor, while stainless steel mesh was chosen as cathode; the anode and cathode were connected to the direct-current power; meantime two 60 W (λmax= 365 nm) UV lamps were used as light source. The microstructures on TiO2before and after being doped with manganese were analyzed by energy disperse X-ray (EDX) and X-ray diffraction (XRD). The performance of degradation of 4-nitroaniline was evaluated by analyzing cracking ratio of 4-nitroaniline ring, the chemical oxygen demand (COD), and total organic carbon (TOC) in remaining solution. Monitored parameters during all the photocatalytic reaction including dissolved oxygen, direct voltage, and radiation dosage of ultraviolet rays were investigated. When dissolved oxygen concentration, direct voltage, and radiation dosage of ultraviolet rays were, respectively, equivalent to 9 mg/L, 24 V, and 1200 μW/cm2, the degradation ratio of 4-nitroaniline reached maximum. The experimental results indicated that cracking ratio of 4-nitroaniline ring and the removal ratio of COD and TOC were, respectively, more than 99%, 85%, and 80% when reaction was run for 10 hours. The values of COD and TOC were, respectively, less than 16 mg/L and 8 mg/L while the experiment was finished.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Razali, Sufia Aqilah, Norazilah Ibrahim, Suhadir Shamsuddin y Mohamad Zaky Noh. "Observation of Charge Ordering Signal in Monovalent Doped Nd0.75Na0.25-xKxMn1O3 (0 ≤ x ≤ 0.10) Manganites". International Journal of Engineering & Technology 7, n.º 4.30 (30 de noviembre de 2018): 85. http://dx.doi.org/10.14419/ijet.v7i4.30.22021.

Texto completo

Resumen

K doping in the compound of Nd0.75Na0.25-xKxMn1O3 (x = 0, 0.05 and 0.10) manganites have been investigated to study its effect on crystalline phase and surface morphology as well as electrical transport and magnetic properties. The structure properties of the Nd0.75Na0.25-xKxMnO3 manganite have been characterized using X-ray diffraction measurement and it proved that the crystalline phase of samples were essentially single phased and indexed as orthorhombic structure with space group of Pnma. The morphological study from scanning electron microscope showed there was an improvement on the grains boundaries and sizes as well as the compactness with K doping suggestively due to the difference of ionic radius. On the other hand, DC electrical resistivity measurement showed all samples exhibit insulating behavior. However, analysis of dlnρ/dT-1 vs. T revealed the clearly peaks could be observed at temperature 210K for x = 0 and the peaks were shifted to the lower temperature around 190 K and 165 K for x = 0.05 and x = 0.1 respectively, indicate the existence of charge ordering (CO) state in the compound. Meanwhile, the investigation on magnetic behavior showed all samples exhibit transition from paramagnetic phase to anti-ferromagnetic phase with decreasing temperature and the TN was observed to shift to lower temperature suggestively due to weakening of CO state

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Kasenova, Sh B., Zh I. Sagintaeva, B. K. Kasenov, M. O. Turtubaeva, А. Nukhuly, Ye Ye Kuanyshbekov y M. A. Isabaeva. "New nanostructured manganites of LaMeIICuZnMnO6 (MeII — Mg, Ca, Sr, Ba)". Bulletin of the Karaganda University. "Chemistry" series 103, n.º 3 (30 de septiembre de 2021): 60–66. http://dx.doi.org/10.31489/2021ch3/60-66.

Texto completo

Resumen

The copper-zinc manganites of LaMeIICuZnMnO6 (MeII — Mg, Ca, Sr, Ba) have been synthesized with the high-temperature interaction of alkaline earth metals carbonates with oxides of lanthanum (III), copper (II), zinc (II) and manganese (III). The synthesized polycrystalline copper-zinc manganites have been grinded on the Retsch vibration mill MM301 (Germany). As a result their nanostructured particles have been obtained. Their sizes have been determined using an electron microscope Mira3 LMU, Tescan. Methods of radiography determined that all synthesized nanostructured copper-zinc manganites crystallize in the cubic syngony with the following parameters of a lattice: LaMgCuZnMnO6 — а = 13.530.02 Å, Vo = 2476.810.06 Å3, Z = 4, Voelect.cell = 619.200.02 Å3, roent = 4.52; pick = 4.500.01 g/cm3; LaCaCuZnMnO6 — а = 13.690.02 Å, Vo = 2565.730.06 Å3, Z = 4, Voelect.cell. = 641.430.02 Å3, roent = 4.43; pick = 4.410.01 g/cm3; LaSrCuZnMnO6 — а = 13.910.02 Å, Vo = 2691.420.06 Å3, Z = 4, Voelect.cell = 672.850.02 Å3, roent = 4.99; pick. = 4.960.01 g/cm3; LaBaCuZnMnO6 — а = 14.550.02 Å, Vo = 3080.270.06 Å3, Z = 4, Voelect.cell = 770.070.02 Å3, roent = 4.95; pick = 4.940.01 g/cm3. The X-ray investigations demonstrated that the values of lattice parameters of the studied copper-zinc manganites have been increased from Mg to Ba. As a result of the investigations, these compounds can be included in Pm3m spatial group.

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Vishniakov, Aleksei V., Iurii O. Fedorov y Andrei Iu Chikin. "Improving the technology of manganese ore X-ray radiometric separation". Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal 1 (30 de marzo de 2021): 79–87. http://dx.doi.org/10.21440/0536-1028-2021-2-79-87.

Texto completo

Resumen

Introduction. In addition to the classical methods of manganese ore processing, a lower-cost and more environmentally friendly technology of X-ray radiometric separation (XRS) has been developed in the last twenty years. The technology has been embraced by enterprises and applied to improve the efficiency of manganese deposits development. The article provides original results of the research carried out by Irgiredmet institute concerning the development of the procedure and technology of manganese ore XRS. Research methodology. The XRS methodology is based on the X-ray fluorescence (XRF) method of elements detection common in geophysical practice. A methodological task of these method is to find manganese in ore containing not only manganese but also iron, as soon as the two elements possess characteristic X-ray radiation (CXR) close in energy and mutually affect the accuracy of their detection by the X-ray fluorescence analyzers. The chosen research methodology allowed developing a new way of keeping records of the elements when solving the problems of manganese ore sampling and sorting. Research results. A new and efficient algorithm of sampling manganese and iron has been developed and tested on different types of manganese and ferromanganese ore. The ratio of CXR of the detected elements to the total sum of the scattered radiation (SR) and these elements CXR intensity set by a special spectral coefficient k is such universal criterion which promotes to more accurate detection of manganese and iron content in lumps.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Sánchez-España, Javier y Iñaki Yusta. "Low-crystallinity products of trace-metal precipitation in neutralized pit-lake waters without ferric and aluminous adsorbent: Geochemical modelling and mineralogical analysis". Mineralogical Magazine 79, n.º 3 (junio de 2015): 781–98. http://dx.doi.org/10.1180/minmag.2015.079.3.19.

Texto completo

Resumen

AbstractThe removal of dissolved trace metals during neutralization of acid mine drainage has usually been described and modelled as a progressive, pH-dependent sorption onto standard ferric or aluminous adsorbent. In the absence of adsorbent mineral surfaces, trace metals tend to form amorphous to low-crystallinity compounds which are often difficult to characterize. Here, we study the behaviour of the more soluble metals (Cu2+, Zn2+, Mn2+, Co2+, Ni2+, Cd2+) in the absence of ferric and aluminous adsorbent by neutralization experiments with waters from two acidic pit lakes. The objectives of our study were to identify the mineral products formed by trace-metal precipitation and the pH ranges at which these metals are removed from the solutions. Both geochemical modelling and detailed mineralogical and chemical analyses (XRD, SEM, TEM, XRF, ICP-AES) were undertaken to characterize the products. The schwertmannite and hydrobasaluminite colloids formed in the initial neutralization stages were removed from the waters at pH 3.5 and 5.1, respectively. These two minerals had previously adsorbed the Cr3+ and Pb2+ initially present in the solutions. The Cu precipitates were amorphous to X-rays, though chemical and modelling data suggest that Cu probably precipitated as a precursor of brochantite (Cu4(SO4)(OH)6·2H2O) at pH >6.0, together with minor quantities of other Cu hydroxysulfates (langite, antlerite) and Cu(OH)2. At higher pH, other divalent metals (Zn2+, Mn2+) precipitated as silicates, carbonates and/or (possibly) minor oxides and (oxy)hydroxides. The high concentration of aqueous SiO2 in the solutions allowed Zn to precipitate as willemite (Zn2SiO4) at pH >7.0. Similarly, the presence of inorganic carbon (originally as CO2 (aq.)) greatly influenced the nature of the corresponding precipitate of Mn. This metal was initially present as Mn2+ and experienced a partly oxidative precipitation forming, in combination with Mg2+, the hydroxyl carbonate desautelsite (Mg6Mn2(CO3)(OH)16·4H2O) at pH 9.0–10.0. The formation of Mn3+/Mn4+ oxides and hydroxides (hausmannite, manganite, birnessite) could not be demonstrated, although geochemical calculations support their subordinate formation. Other metallic cations such as Co2+, Ni2+ and Cd2+ did not form discrete mineral phases but were totally removed by sorption onto and/or incorporation into the cited Zn and Mn compounds. The discrepancies between theoretical and demonstrated mineralogy and the significance of these minerals for future pit-lake remediation initiatives are discussed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Turki, D., R. Cherif, E. K. Hlil, M. Ellouze y F. Elhalouani. "The effect of Co doping on structural, magnetic and magnetocaloric properties of La0.8Ca0.2Mn1-xCoxO3 perovskites (0 ≤ x ≤ 0.3)". International Journal of Modern Physics B 28, n.º 32 (14 de diciembre de 2014): 1450230. http://dx.doi.org/10.1142/s0217979214502300.

Texto completo

Resumen

Studies of the structural, magnetic and magnetocaloric properties of polycrystalline La 0.8 Ca 0.2 Mn 1-x Co x O 3 compounds (0 ≤ x ≤0.3) perovskite manganites were carried out. Samples were synthesized by sol–gel process and then heated at 1000°C for 3 h. X-ray powder diffraction and magnetic measurements were used to investigate the structural and magnetic properties. Rietveld analysis shows that the samples crystallize in the orthorhombic structure with Pnma space group. Crystallographic analysis shows a variation in lattice parameters as cobalt substitution increases, accompanied by a variation in the interatomic distances and a small increase in MT–O–MT angles (MT = cobalt and manganese). Magnetocaloric studies on La 0.8 Ca 0.2 Mn 1-x Co x O 3 compounds with x = 0 and x = 0.2 have been investigated by measuring the magnetization as a function of temperature. At 2 T, the maximum magnetic entropy [Formula: see text] is about 3.09 J⋅Kg-1⋅K-1 and 1.123 J⋅Kg-1⋅K-1 for x = 0 and 0.2, respectively. Besides, the RCP value decreases with increasing Co content from 55.845 J⋅Kg-1 to 49.971 J⋅Kg-1. Also, the existence of Griffiths Phase and its influence in the phase transition is discussed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Ellouze, M., W. Boujelben y H. Fuess. "Rietveld refinement X-ray powder data of Pr0.7Ba0.3MnO3". Powder Diffraction 18, n.º 1 (marzo de 2003): 29–31. http://dx.doi.org/10.1154/1.1515296.

Texto completo

Resumen

Powder X-ray diffraction (XRD) data were collected for Pr0.7Ba0.3MnO3. This sample was prepared using the conventional solid state reaction by mixing Pr6O11, Mn2O3, and BaCO3 up to 99.9% purity at 1400 °C in air for 60 h. XRD analysis using the Rietveld method was carried out and it was found that this manganite sample has orthorhombic symmetry with Pnma space group. The lattice parameters are found to be a=5.4900 Å, b=7.7578 Å, and c=5.5227 Å.

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Charny, D., O. Shevchenko y V. Nesterovskyi. "COMPOSITION AND PROPERTIES OF MINERAL NON-FORMATIONS ON A FILTER SUBSTRATE DURING TREATMENT OF UNDERGROUND WATER FROM IRON AND MANGANESE". Visnyk of Taras Shevchenko National University of Kyiv. Geology, n.º 4 (83) (2018): 84–90. http://dx.doi.org/10.17721/1728-2713.83.12.

Texto completo

Resumen

Purpose. To determine composition and properties of iron-manganese crusts formed on grainy filtration load granules surface in the process of underground waters cleaning from Fe2+ and Mn2+, and to determine the application limits and perspective trends of the offered water preparation technology development, conditioned by the properties of these crusts. Method. For the analysis of physical and chemical properties of iron-manganese crusts analytical methods are used on the base of leaching and determination of iron and manganese content in solution and for more precise definition of crust qualitative composition an X-ray fluorescent photography spectrometry is used. For determination of crystalline structure an X-ray photography diffractometry was used, and the thickness of film was determined by mechanical micrometry. Processing of the received information and graphic interpretation of data is executed with application of LibreOffice Cacl, Gnumeric and PSPP software. Results. Determined physicochemical characteristics of iron-manganese crust formed on granules surface of grainy filtration load, the metrical sizes of film are determined: thickness and mass, analytically determined by lixiviating contents of iron and manganese in a crust. Manganites, that form a crust, are dispersion characterized; on some occasion considerable amount of roentgenoamorphous phase is formed, and in other - a crystalline form predominates as todorokite. In our opinion, it is determined by correlation of Mn/Fe concentrations in initial water. Results of crust measuring on the granules of filtration load on the water treatment station in town of Uzin is the following: thickness 0,518±0,209 mm; mass 0,0039±0,0004 g, manganese contents and total iron, accordingly, 115,59±4,33 mg/dm3 and 55,33±30,85 mg/dm3. Manganese and iron contents, which were lixiviated from the crusts of filtration load on the water treatment station in Chervona Sloboda village, accordingly: 55,067±10,946 mg/dm3; 100,476±4,284 mg/dm3. Scientific novelty. Firstly possibility of forming catalytic crust (film) from iron-manganese compositions on the filtration load surface is experimentally proved, among those compositions there are higher oxides of manganese in considerable volumes. Having determined their crystalline and chemical structure, it was proved that they provide the effective removal of iron and manganese over the norm contents from water and in a perspective can be used for the removal of a number of low valency cations among which the removal of Ñà2+ and Âr2+ is experimentally confirmed. Practical significance. Based on the known geobiochemical cycles of iron and manganese a new water treatment technology and also a new filter material with considerable potential of subsequent improvement and application are gotten, unlike classic technologies of manganese removal this method does not require bringing in additional reagents at Mn(II) → Mn(IV) oxidation.

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Нигьматуллина, И. И., В. В. Парфенов, Р. М. Еремина, Т. П. Гаврилова y И. В. Яцык. "Исследование Sr-допированных ферроманганитов иттербия методами ЭПР и мессбауэровской спектроскопии". Физика твердого тела 60, n.º 5 (2018): 933. http://dx.doi.org/10.21883/ftt.2018.05.45789.333.

Texto completo

Resumen

AbstractIn this paper, we have studied the crystal structure of strontium-substituted manganite and ytterbium ferromanganites Yb_0.82Sr_0.18Mn_1 – x Fe_ x O_3 ( x = 0–0.2) by using X-ray diffraction analysis. Magnetic microstructure has been studied by electron paramagnetic resonance and nuclear gamma-resonance (Mössbauer) spectroscopy. We have observed phase separation in the ceramics for antiferromagnetic, superparamagnetic, and ferromagnetic phases.

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Caudron, Eric, Régis Cueff, Christophe Issartel, N. Karimi, Frédéric Riffard, Sébastien Perrier y Henri Buscail. "Yttrium Implantation and Manganese Addition Element Effects on the High Temperature Oxidation Resistance of a Model Steel". Materials Science Forum 595-598 (septiembre de 2008): 897–905. http://dx.doi.org/10.4028/www.scientific.net/msf.595-598.897.

Texto completo

Resumen

Manganese addition and subsequent yttrium implantation effects on extra low carbon steel were studied by Rutherford Backscattering Spectrometry (RBS), Reflection High Energy Electron Diffraction (RHEED), X-ray Diffraction (XRD) and Glancing Angle X-ray Diffraction (GAXRD). Thermogravimetry and in situ X-Ray Diffraction at 700°C and PO2=0.04 Pa for 24h were used to determine the manganese alloying addition and subsequent yttrium implantation effects on reference steel oxidation resistance at high temperatures. This study clearly shows the combined effect of manganese alloying addition and subsequent yttrium implantation which promotes the formation of several yttrium mixed oxides seem to be responsible for the improved reference steel oxidation resistance at high temperatures.

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Badelin, A., Z. Datskaya, S. Estemirova, V. Karpasyuk y D. Merkulov. "Effect of ageing on magnetic and electrical properties of Ti–substituted La-Sr manganites". EPJ Web of Conferences 185 (2018): 06002. http://dx.doi.org/10.1051/epjconf/201818506002.

Texto completo

Resumen

The changes of structural, magnetic and electrical parameters of ceramic La0.8-xSr0.2+xMn1-xTixO3+γ (0.025 ≤ x ≤ 0.150) manganites during long-term storage at room temperature and after thermal cycling were investigated. The unit cell volume (V) of all manganites decreased over time. Most considerable decrease of V and broadening of X-ray diffraction lines width were observed in the samples with high quantity of titanium. During the storage period magnetization (σ) and Curie point (Tc) of manganites with relatively low Ti content decreased, while the compositions with high values of “x” exhibited some trend of σ and Tc increase. The resistance of the samples with x < 0.100 increased over time. Fluctuations of magnetization of all thermal-aged samples were within the error of measurement, and Curie point of manganites with x = 0.150 showed the rise. From the data obtained it might be inferred that ageing phenomena in Ti-substituted manganites can be associated with oxidation processes, the transfer of Ti4+ to vacant sites in rare-earth sublattice and formation of microinhomogeneities.

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Touthang, Jangkhohao y Mamata Maisnam. "Structural and electrical studies of sol–gel synthesized nanocrystalline hexagonal yttrium iron manganite ceramics". Modern Physics Letters B 31, n.º 07 (10 de marzo de 2017): 1750066. http://dx.doi.org/10.1142/s021798491750066x.

Texto completo

Resumen

Hexagonal yttrium manganites, YMnO3, are interesting materials for their multiferroic behavior. Substituting suitable cations either at the Y-site or Mn-site offers great opportunities to produce a variety of manganites and tune their properties. Nanocrystalline yttrium iron manganites with the compositional formula Y[Formula: see text]Fe[Formula: see text]MnO3, [Formula: see text] = 0.0, 0.10, 0.15, 0.20 and 0.25, were synthesized by sol–gel autocombustion method. The prepared samples were heated at 1100[Formula: see text]C for 1 h. Another set of samples with compositional formula YFe[Formula: see text]Mn[Formula: see text]O3, [Formula: see text] = 0.0, 0.10, 0.15, 0.20 and 0.25, were also synthesized by the same method and heated at 1100[Formula: see text]C for 1 h. Various characterizations were done on these manganite systems synthesized by substituting iron at different sites. X-ray diffraction (XRD) technique studied the structure of the samples and analysis of XRD patterns confirmed the formation of hexagonal phase in the samples. Structural parameters such as lattice constants, crystallite size, theoretical density, etc. were determined using the XRD data. The unit cell dimensions have been found to agree with the standard data and the Debye–Scherrer crystallite size obtained from XRD data ranges from 42 nm to 77 nm. The room temperature frequency variations of electrical properties such as dielectric constant, dielectric loss and AC conductivity were measured in the range of 100 Hz–2 MHz and the variations showed a dispersive behavior for all the samples. The various measurements and the results obtained were studied and discussed in the paper.

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Mohamed, Zakiah, Intan Syazwani Shahron, Norazila Ibrahim y Mohd Fauzi Maulud. "Influence of Ruthenium Doping on the Crystal Structure and Magnetic Properties of Pr0.67Ba0.33Mn1–xRuxO3 Manganites". Crystals 10, n.º 4 (11 de abril de 2020): 295. http://dx.doi.org/10.3390/cryst10040295.

Texto completo

Resumen

This study reports the structural, morphological, and magnetic properties of ruthenium doping at the manganese site in Pr0.67Ba0.33MnO3 manganites. Rietveld refinement X-ray powder diffraction (XRD) data show that Pr0.67Ba0.33MnO3 and Pr0.67Ba0.33Mn0.9Ru0.1O3 crystallize in an orthorhombic perovskite structure with the Pnma space group. Doping with Ru yields an increment in the lattice parameter and unit cell volume. In addition, small changes in the Mn–O–Mn bond angle and bond distance are observed. Field emission scanning electron microscopy (FESEM) is used to examine the surface morphology of the samples. Fourier transform infrared spectroscopy (FTIR) reveals that the Mn–O and metal–oxygen bonds appear at the 600 and 900 cm−1 bands, respectively. The AC magnetic susceptibility measurement studies confirm that a paramagnetic (PM) to ferromagnetic (FM) transition exists at 130 and 153 K for the Pr0.67Ba0.33MnO3 and Pr0.67Ba0.33Mn0.9Ru0.1O3 samples, respectively.

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Bell, Anthony M. T. y C. Michael B. Henderson. "Rietveld refinement of the crystal structures of Rb2XSi5O12(X= Ni, Mn)". Acta Crystallographica Section E Crystallographic Communications 72, n.º 2 (27 de enero de 2016): 249–52. http://dx.doi.org/10.1107/s2056989016001390.

Texto completo

Resumen

The synthetic leucite silicate framework mineral analogues Rb2XSi5O12{X= Ni [dirubidium nickel(II) pentasilicate] and Mn [dirubidium manganese(II) pentasilicate]} have been prepared by high-temperature solid-state synthesis. The results of Rietveld refinements, using X-ray powder diffraction data collected using CuKα X-rays, show that the title compounds crystallize in the space groupPbcaand adopt the cation-ordered structure of Cs2CdSi5O12and other leucites. The structures consist of tetrahedral SiO4andXO4units sharing corners to form a partially substituted silicate framework. Extraframework Rb+cations sit in channels in the framework. All atoms occupy the 8cgeneral position for this space group. In these refined structures, silicon andXatoms are ordered onto separate tetrahedrally coordinated sites (T-sites). However, the Ni displacement parameter and the Ni—O bond lengths suggest that for theX= Ni sample, there may actually be some T-site cation disorder.

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Rogers, K. D. y D. Cossins. "An X-ray diffraction study of pyrolytic manganese dioxide". Powder Diffraction 8, n.º 1 (marzo de 1993): 18–24. http://dx.doi.org/10.1017/s0885715600017681.

Texto completo

Resumen

The thermal decomposition of aqueous manganese nitrate has been studied under a range of experimental conditions to scientifically assess the pyrolysis processes employed by the tantalum capacitor industry. The crystalline phase and form of the manganese oxides produced are compared by X-ray diffraction and scanning electron microscopy. Those experimental conditions producing materials with the lowest resistivity are identified. The technological significance of the decomposition process is discussed and initial results from a novel pyrolysis technique are presented.

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Garg, K. B., N. L. Saini, B. R. Sekhar, R. K. Singhal, B. Doyle, S. Nannarone, F. Bondino, E. Magnano, E. Carleschi y T. Chatterji. "Doped holes and Mn valence in manganites: a polarized soft x-ray absorption study of LaMnO3and quasi-2D manganite systems". Journal of Physics: Condensed Matter 20, n.º 5 (17 de enero de 2008): 055215. http://dx.doi.org/10.1088/0953-8984/20/5/055215.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Jabua, Malkhaz, Detlev Gotta, Thomas Strauch, Christian Weidemann, Burkhard Fricke y Khalid Rashid. "Kα X-ray emission in manganese compounds". Spectrochimica Acta Part B: Atomic Spectroscopy 121 (julio de 2016): 11–17. http://dx.doi.org/10.1016/j.sab.2016.04.006.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

GARCÍA, J., J. BLASCO, M. C. SÁNCHEZ, M. G. PROIETTI y G. SUBÍAS. "LACK OF ATOMIC CHARGE LOCALIZATION IN TRANSITION METAL MIXED VALENCE OXIDES". Surface Review and Letters 09, n.º 02 (abril de 2002): 821–30. http://dx.doi.org/10.1142/s0218625x02001835.

Texto completo

Resumen

We review our recent studies on the occurrence of atomic charge localization in magnetite and half-doped manganites. X-ray resonant scattering experiments at the iron K-edge of magnetite and X-ray absorption spectroscopy at the Mn K-edge of Ca-doped manganites show the lack of charge localization on the transition metal atom, either temporal or spatial. The evolution of the intensity of (002) and (006) forbidden reflections in magnetite across the Verwey transition, as a function of the incoming X-ray beam energy, the azimuthal angle and the polarization of the scattering process, indicates that the atomic anomalous scattering factors for the octahedral iron ions are identical to each other, i.e. all of them show an identical electronic state. High resolution XANES spectra of RE 1-x Ca x MnO 3 series cannot be reproduced by a linear combination of REMnO3 and CaMnO 3 spectra. Accordingly, the electronic state of the Mn atom in these intermediate compounds cannot be described as a bimodal distribution of Mn 3+ and Mn 4+ pure ionic states. The claimed experimental evidence of charge ordering in Mn 3+/ Mn 4+=1 manganites proposed from X-ray resonant scattering experiments has also been critically re-examined. We show that although these experiments prove the existence of two kinds of Mn atoms, they cannot be identified as Mn 3+ and Mn 4+ ions. Moreover, the so-called charge-ordering (CO) and orbital-ordering (OO) resonant scattering reflections are naturally explained due to the presence of local distortions without including any ordering of the Mn d-orbitals.

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Hepp, Nancy M. "X-Ray Fluorescence Determination of Manganese in FD&C Blue No. 1". Journal of AOAC INTERNATIONAL 81, n.º 1 (1 de enero de 1998): 89–92. http://dx.doi.org/10.1093/jaoac/81.1.89.

Texto completo

Resumen

Abstract An X-ray fluorescence (XRF) method was developed for determining manganese in FD&C Blue No. 1 from simply prepared pressed pellets. Results were compared with those of atomic absorption spectroscopy (AAS) of acid-digested or ashed samples. Levels of manganese determined by XRF and AAS were equivalent. The limit of detection (3σ) for the XRF method was 3µg manganese/g dye. The 95% confidence interval at the specification level was 100 ± 10 μg manganese/g dye

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Głuchowski, Paweł, Ruslan Nikonkov, Robert Tomala, Wiesław Stręk, Tatsiana Shulha, Maria Serdechnova, Aleksej Zarkov et al. "Impact of Alkali Ions Codoping on Magnetic Properties of La0.9A0.1Mn0.9Co0.1O3 (A: Li, K, Na) Powders and Ceramics". Applied Sciences 10, n.º 24 (8 de diciembre de 2020): 8786. http://dx.doi.org/10.3390/app10248786.

Texto completo

Resumen

The aim of the work was to check how the introduction of alkali and cobalt ions into a manganese structure can affect the structural disorder and, in consequence, lead to the changes (improvements) of magnetic properties. The high-pressure sintering technique was applied to check if the external factor can modify the magnetization of manganites. Nanocrystalline La0.9A0.1Mn0.9Co0.1O3 (where A is Li, K, Na) powders were synthesized by the combustion technique. The respective powders were used for nanoceramics preparation by the high-pressure sintering technique. The structure and morphology of the compounds were studied by X-ray powder diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Magnetization studies for all compounds were performed in order to check the changes induced by either codoping or the sintering pressure. It was found that the type of the dopant ion and sintering pressure produced significant changes to the magnetic properties of the studied compounds. Alkali ions lead to the stabilization of Co ions in the +2 oxidation state and the formation of positive exchange interactions Mn3+–Mn4+ and Co2+–Mn4+ and the subsequent increase in remanent magnetization. High sintering pressure leads to a decrease in grain size and reduction of long-range ferromagnetic order and lower magnetization.

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Knowles, Kevin M., Mary E. Vickers, Anjan Sil, Yung-Hoe Han y Périne Jaffrenou. "X-ray powder diffraction and electron diffraction studies of the thortveitite-related L phase, (Zn,Mn)2V2O7". Acta Crystallographica Section B Structural Science 65, n.º 2 (20 de febrero de 2009): 160–66. http://dx.doi.org/10.1107/s0108768108042444.

Texto completo

Resumen

The phase designated γ-Zn3(VO4)2 reported as a minor second phase in zinc oxide-based varistor materials doped with vanadium oxide and manganese oxide is shown to be the L phase, (Zn1 − x Mn x )2V2O7 (0.188 < x < 0.538), in the pseudo-binary Mn2V2O7–Zn2V2O7 system. Analysis of X-ray powder diffraction patterns and electron diffraction patterns of this phase shows that the previously published a, c and β values for this thortveitite-related phase are incorrect. Instead, Rietveld refinement of the X-ray powder pattern of the L phase shows that it has a monoclinic C lattice with Z = 6, with a = 10.3791 (1), b = 8.5557 (1), c = 9.3539 (1) Å and β = 98.467 (1)°. Although prior convergent-beam electron diffraction work of `γ-Zn3(VO4)2' confirmed the C Bravais lattice, the space group was found to be Cm rather than C2/m, the difference perhaps arising from the inability of the X-rays to detect small displacements of oxygen. Attempts to refine the structure in Cm did not produce improved R factors. The relationship between the crystal structure of the L phase and the high-temperature C2/m β′-Zn2V2O7 thortveitite-type solid solution is discussed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Dang, Trung Dung. "STUDY ON THE PREPARATION OF MANGANESE DIOXIDE VIA CATHODIC ELECTROLYSIS". Vietnam Journal of Science and Technology 55, n.º 5B (24 de marzo de 2018): 34. http://dx.doi.org/10.15625/2525-2518/55/5b/12207.

Texto completo

Resumen

A novel synthesis method was developed to prepare manganese dioxide via cathodic electrolysis in potassium permanganate solution. The morphology and the composition of the synthesized products were analyzed by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction spectroscopy (XRD). The electrolyzed products include two kinds of materials: amorphous and crystalline manganese dioxide. The manganese dioxides were formed by cathodic reduction via two reaction mechanisms: direct and indirect electrochemical reactions. The electrolysis current performance strongly depends on the electrolyte solution temperature, applied voltage and not clearly depends on electrolyte solution concentration. With high current performance and uniformity products, the cathodic reduction of potassium permanganate is promising method for manganese dioxide fabrication.

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Caldwell, M. L., H. H. Richardson y M. E. Kordesch. "Optical Properties of Manganese Doped Amorphous and Crystalline Aluminum Nitride Films". MRS Internet Journal of Nitride Semiconductor Research 5, S1 (2000): 159–66. http://dx.doi.org/10.1557/s1092578300004221.

Texto completo

Resumen

An aluminum nitride (AlN) film deposited on silicon (100) was used as the substrate for growing manganese (Mn) doped AlN film by metal organic chemical vapor deposition (MOVCD). The (15.78 µm) under layer of AlN was grown at 615°C at a pressure of 10−4 Torr. The (2.1 µm) top layer of Mn-AlN was grown at the same temperature and pressure but doped with pulse valve introduction of the manganese decacarbonyl (100 ms on, 100 ms off). The film was then characterized ex situ with IR reflectance microscopy, X-ray diffraction, scanning electron microscopy imaging, cathodoluminescence, and X-ray fluorescence. The IR reflectance measurements showed a strong (A1) LO mode for AlN at 920 cm−1 and 900 cm−1 with a shoulder at 849 cm−1. X-ray Diffraction yielded three diffraction peaks at a 2θ position of 33, 36 and 38 degrees corresponding to 100, 002, and 101 lattice planes respectively. Cathodoluminescence results show strong visible emitted light from incorporated manganese. The relative percentage of manganese to aluminum was below the detection limit (0.01 %) of the X-ray fluorescence spectrometer. Amorphous Mn doped AlN films have also been grown using a low temperature atomically abrupt sputter epitaxial system. The amorphous Mn doped AlN showed no cathodoluminescence.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Welfringer, J., P. Benoit y M. Guyon. "Measurement of Macrosegregations of Steels by X-Ray Microfluorescence". Advances in X-ray Analysis 35, B (1991): 1301–6. http://dx.doi.org/10.1154/s037603080001363x.

Texto completo

Resumen

AbstractAn apparatus based on X-ray microfluorescence has been developed at IRSID in order to routinely and quantitatively determine the state of segregation in steels. The equipment consists principally of an iron anticathode X-Ray tube, a Si(Li) energy - dispersive detector and a “on the fly” operation in a multi-scale analysis mode. The acquisition of a chromium or manganese mapping in a (150 × 150 mm2) steel sample is possible over a total time of about one hour. The calibration curves for chromium or manganese are linear for the usual compositions of steels between 0.3% to 3%.

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Zawawi, Rabiatul Adawiyah, Nurul Nasuha Khairulzaman, Suhadir Shamsuddin y Norazila Ibrahim. "Comparative Study on Structural, Electrical Transport and Magnetic Properties of Cr-Doped in Charge-Ordered Pr0.75Na0.25Mn1-Xcrxo3 and Nd0.75Na0.25Mn1-Ycryo3 Manganites". International Journal of Engineering & Technology 7, n.º 4.30 (30 de noviembre de 2018): 76. http://dx.doi.org/10.14419/ijet.v7i4.30.22016.

Texto completo

Resumen

Cr doping in charge-ordered Pr0.75Na0.25Mn1-xCrxO3 and Nd0.75Na0.25Mn1-yCryO3 have been synthesized using conventional solid-state method to investigate its effect on structural, electrical transport and magnetic properties. X-ray diffraction (XRD) analysis for both compounds showed that the samples were crystallized in an orthorhombic structure with Pnma group. The unit cell volume value decrease as the Cr-doped increased indicating the possibility of Mn3+ ion was replaced by Cr3+ due to the different of ionic radius. The temperature dependence of electrical resistivity showed an insulating behavior down to the lower temperature the both parent compound (x = 0 and y = 0). Successive substitution of Cr at Mn-site in Pr0.75Na0.25Mn1-xCrxO3 manganites induced the metal-insulator (MI) transition temperature around TMI~120 K and TMI~122 K for x = 0.02 and x = 0.04 samples respectively suggestively due to the enhancement of double-exchange (DE) mechanism as a result of suppress the CO state. Analysis of resistivity data of dlnρ/dT-1 vs. T in Nd0.75Na0.25Mn1-yCryO3 manganite, showed a peak around 210 K and 160 K for y = 0 and 0.02 samples respectively while no peak was observed for y = 0.05 sample indicate the charge-ordered (CO) weakened. AC susceptibility, χ’ measurements in Pr0.75Na0.25Mn1-xCrxO3 exhibits paramagnetic to ferromagnetic-like with curie temperature, TC increases from 132 K for x = 0.02 to 141 K for x = 0.04 with Cr content indicate the suppression of CO state meanwhile in Nd0.75Na0.25Mn1-yCryO3 showed paramagnetic to anti-ferromagnetic transition as Neel temperature TN increases from 115 K for y = 0.02 to 125 K for y = 0.05.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Artículos de revistas sobre el tema "Manganite X-rays"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros