Relevant bibliographies by topics / Ordered perovskites

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Academic literature on the topic 'Ordered perovskites'

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Published: 4 June 2021
Last updated: 15 February 2022

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Journal articles on the topic "Ordered perovskites"

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Mitchell, Roger H., Mark D. Welch, and Anton R. Chakhmouradian. "Nomenclature of the perovskite supergroup: A hierarchical system of classification based on crystal structure and composition." Mineralogical Magazine 81, no. 3 (June 2017): 411–61. http://dx.doi.org/10.1180/minmag.2016.080.156.

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AbstractOn the basis of extensive studies of synthetic perovskite-structured compounds it is possible to derive a hierarchy of hettotype structures which are derivatives of the arisotypic cubic perovskite structure (ABX3), exemplified by SrTiO3 (tausonite) or KMgF3 (parascandolaite) by: (1) tilting and distortion of the BX6 octahedra; (2) ordering of A- and B-site cations; (3) formation of A-, B- or X-site vacancies. This hierarchical scheme can be applied to some naturally-occurring oxides, fluorides,hydroxides, chlorides, arsenides, intermetallic compounds and silicates which adopt such derivative crystal structures. Application of this hierarchical scheme to naturally-occurring minerals results in the recognition of a perovskite supergroup which is divided into stoichiometric and non-stoichiometricperovskite groups, with both groups further divided into single ABX3 or double A2BB'X6 perovskites. Subgroups, and potential subgroups, of stoichiometric perovskites include: (1) silicate single perovskites of the bridgmanite subgroup;(2) oxide single perovskites of the perovskite subgroup (tausonite, perovskite, loparite, lueshite, isolueshite, lakargiite, megawite); (3) oxide single perovskites of the macedonite subgroup which exhibit second order Jahn-Teller distortions (macedonite, barioperovskite); (4) fluoride singleperovskites of the neighborite subgroup (neighborite, parascandolaite); (5) chloride single perovskites of the chlorocalcite subgroup; (6) B-site cation ordered double fluoride perovskites of the cryolite subgroup (cryolite, elpasolite, simmonsite); (7) B-site cation orderedoxide double perovskites of the vapnikite subgroup [vapnikite, (?) latrappite]. Non-stoichiometric perovskites include: (1) A-site vacant double hydroxides, or hydroxide perovskites, belonging to the söhngeite, schoenfliesite and stottite subgroups; (2) Anion-deficient perovskitesof the brownmillerite subgroup (srebrodolskite, shulamitite); (3) A-site vacant quadruple perovskites (skutterudite subgroup); (4) B-site vacant single perovskites of the oskarssonite subgroup [oskarssonite]; (5) B-site vacant inverse single perovskites of the coheniteand auricupride subgroups; (6) B-site vacant double perovskites of the diaboleite subgroup; (7) anion-deficient partly-inverse B-site quadruple perovskites of the hematophanite subgroup.
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Talanov, M. V., V. B. Shirokov, and V. M. Talanov. "Anion order in perovskites: a group-theoretical analysis." Acta Crystallographica Section A Foundations and Advances 72, no. 2 (January 29, 2016): 222–35. http://dx.doi.org/10.1107/s2053273315022147.

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Anion ordering in the structure of cubic perovskite has been investigated by the group-theoretical method. The possibility of the existence of 261 ordered low-symmetry structures, each with a unique space-group symmetry, is established. These results include five binary and 14 ternary anion superstructures. The 261 idealized anion-ordered perovskite structures are considered as aristotypes, giving rise to different derivatives. The structures of these derivatives are formed by tilting ofBO6octahedra, distortions caused by the cooperative Jahn–Teller effect and other physical effects. Some derivatives of aristotypes exist as real substances, and some as virtual ones. A classification of aristotypes of anion superstructures in perovskite is proposed: theAXclass (the simultaneous ordering ofAcations and anions in cubic perovskite structure), theBXclass (the simultaneous ordering ofBcations and anions) and theXclass (the ordering of anions only in cubic perovskite structure). In most perovskites anion ordering is accompanied by cation ordering. Therefore, the main classes of anion order in perovskites are theAXandBXclasses. The calculated structures of some anion superstructures are reported. Comparison of predictions and experimentally investigated anion superstructures shows coherency of theoretical and experimental results.
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Ivanov, S. A., S. G. Eriksson, Roland Tellgren, and Håkan Rundlöf. "A Neutron Diffraction Study of Magnetically Ordered Ferroelectric Materials." Materials Science Forum 443-444 (January 2004): 383–86. http://dx.doi.org/10.4028/www.scientific.net/msf.443-444.383.

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Structural, magnetic, dielectric properties and Mossbauer effect were investigated on complex perovskite with composition AFe2/3B1/3O3(A=Ca,Sr,Pb,Ba; B=W,Te). The most striking feature of this type of complex perovskites is the coexistence of magnetic and antiferroelectric types of ordering in a certain temperature interval. It was found that ferrimagnetic Ca and Sr compounds belong to a partially ordered perovskite structure, and antiferromagnetic Pb phase to a disordered one. The possible models for nuclear and magnetic structures were proposed in accordance with the observed dielectric and magnetic properties.
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Long, Youwen. "High-pressure synthesis and physical properties of A-site ordered perovskites." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C755. http://dx.doi.org/10.1107/s2053273314092444.

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ABO3-type perovskite oxides exhibit a wide variety of interesting physical properties such as superconductivity, colossal magnetoresistance, multiferroic behavior etc. For a simple ABO3 perovskite, if three quarters of the A site is replaced by a transition metal A', then the so-called A-site ordered double perovskite with the chemical formula of AA'3B4O12 can form. Since both A' and B sites accommodate transition metal ions, in addition to conventional B-B interaction, the new A'-A' and/or A'-B interaction is possible to show up, giving rise to the presence of many novel physical properties. Here we will show our recent research work on the high-pressure synthesis of several A-site ordered perovskites as well as a series of interesting physical properties like temperature- and pressure-induced intermetallic charge transfer, negative thermal expansion, magnetoelectric coupling multiferroic and so on. [1-3]
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Belik, Alexei A. "Rise of A-site columnar-ordered A2A′A′′B4O12 quadruple perovskites with intrinsic triple order." Dalton Transactions 47, no. 10 (2018): 3209–17. http://dx.doi.org/10.1039/c7dt04490a.

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Ohtomo, Akira, Suvankar Chakraverty, Hisanori Mashiko, Takayoshi Oshima, and Masashi Kawasaki. "Spontaneous atomic ordering and magnetism in epitaxially stabilized double-perovskites." MRS Proceedings 1454 (2012): 3–13. http://dx.doi.org/10.1557/opl.2012.923.

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ABSTRACTWe report on the atomic ordering of B-site transition-metals and magnetic properties in double-perovskite oxides, La2CrFeO6 (LCFO) and La2VMnO6 (LVMO), which have never been reported to exist in ordered forms. These double-perovskite oxides are particularly interesting because of possible ferromagnetism (expected from the Kanamori-Goodenough rule for LCFO) and half-metallic antiferromagnetism (predicted for LVMO). Using pulsed-laser deposition technique with single solid-solution targets, we have prepared epitaxial films in ordered forms. Despite similar ionic characters of constituent transition-metals in each compound, the maximum B-site order attained was surprisingly high, ∼90% for LCFO and ∼80% for LVMO, suggesting a significant role of epitaxial stabilization in the spontaneous ordering process. Magnetization and valence state characterizations revealed that the magnetic ground state of both compounds was coincidently ferrimagnetic with saturation magnetization of ∼2μBper formula unit, unlike those predicted theoretically. In addition, they were found to be insulating with optical band-gaps of 1.6 eV and 0.9 eV for LCFO and LVMO, respectively. Our results present a wide opportunity to explore novel magnetic properties of binary transition-metal perovskites upon epitaxial stabilization of the ordered phase.
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Flerov, I. N., M. V. Gorev, K. S. Aleksandrov, A. Tressaud, J. Grannec, and M. Couzi. "Phase transitions in elpasolites (ordered perovskites)." Materials Science and Engineering: R: Reports 24, no. 3 (November 1998): 81–151. http://dx.doi.org/10.1016/s0927-796x(98)00015-1.

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Caracas, Razvan, and R. E. Cohen. "Prediction of polar ordered oxynitride perovskites." Applied Physics Letters 91, no. 9 (August 27, 2007): 092902. http://dx.doi.org/10.1063/1.2776370.

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Lufaso, Michael W., Paris W. Barnes, and Patrick M. Woodward. "Structure prediction of ordered and disordered multiple octahedral cation perovskites using SPuDS." Acta Crystallographica Section B Structural Science 62, no. 3 (May 15, 2006): 397–410. http://dx.doi.org/10.1107/s010876810600262x.

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The software package SPuDS has previously been shown to accurately predict crystal structures of AMX 3 and A 1 − x A′ x MX 3 perovskites that have undergone octahedral tilting distortions. This paper describes the extension of this technique and its accuracy for A 2 MM′X 6 ordered double perovskites with the aristotype Fm\overline 3m cubic structure, as well as those that have undergone octahedral tilting distortions. A survey of the literature shows that roughly 70% of all ordered double perovskites undergo octahedral tilting distortions. Of the 11 distinct types of octahedral tilting that can occur in ordered perovskites, five tilt systems account for ∼97% of the reported structures. SPuDS can calculate structures for the five dominant tilt systems, Fm\overline 3m (a 0 a 0 a 0), I4/m (a 0 a 0 c −), R\overline 3 (a − a − a −), I2/m (a 0 b − b −) and P21/n (a − a − b +), as well as two additional tilt systems, Pn\overline 3 (a + a + a +) and P4/mnc (a 0 a 0 c +). Comparison with reported crystal structures shows that SPuDS is quite accurate at predicting distortions driven by octahedral tilting. The favored modes of octahedral tilting in ordered double perovskites are compared and contrasted with those in AMX 3 perovskites. Unit-cell pseudosymmetry in Sr- and Ca-containing double perovskites is also examined. Experimentally, Sr2 MM′O6 compounds show a much stronger tendency toward pseudosymmetry than do Ca2 MM′O6 compounds with similar tolerance factors.
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Claridge, John. "Crystal Chemistry and Symmetry based approaches to multiferroics." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C977. http://dx.doi.org/10.1107/s2053273314090226.

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The area of improper ferroelectrics and potentially multiferroics has recently received significant attention do the prediction that a combination of a–a–c+ tilting and layered ordering of the A site cations along [001]perov in perovskite ABX3 systems or in the even n Ruddlesden Popper (RP) phases (An+1BnX3n+1), leads to non-centrosymmetric structures which are predicted to have significant switchable polarisations. Two practical examples will be discussed: (i) Suitable doping of the RP phase SrLn2Fe2O7 can induce a polar tilted ground state where weak ferromagnetism and magnetocelecricity are induced by the appearance of the polar tilted state. The transition temperatures and phase sucession is dependant on the degree of doping. (ii) The oxide heterostructure [(YFeO3)5(LaFeO3)5]40,which is magnetically ordered and piezoelectric at room temperature, has been constructed from two weak ferromagnetic AFeO3 perovskites with different A cations using RHEED-monitored pulsed laser deposition.1 Here we elaborate a superspace description of cation ordering in tilted perovskites that allows the prediction of the symmetry of arbitrary cation ordered superlattices, along <100>perov, <110>perov and <111>perov and ordering of both A and B cations, of the various tilted perovskites, which also rationalizes the observed domain structures. This approach is expaned to include magnetic symmetry and the potential for finding other suitable structural distortions in non-perovskite systems will be discussed.
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Dissertations / Theses on the topic "Ordered perovskites"

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Knapp, Meghan C. "Investigations into the structure and properties of ordered perovskites, layered perovskites, and defect pyrochlores." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1149097068.

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Russell, David D. "Design, synthesis, crystal structure and magnetic properties of novel osmium-based B-site ordered double perovskites." Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10011271.

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Transition metal oxides (TMOs) with face centered cubic arrangement of magnetic ions are composed of triangular sub-lattices. When antiferromagnetic (AFM) interactions of the same strengths between all three pathways in triangular settings are in place, spin constraints cannot be fulfilled simultaneously and the system undergoes geometric magnetic frustration (GMF). The purpose of the work presented in this thesis is to better understand the criteria for a system to undergo GMF. To achieve this, the novel B-site ordered double perovskites Ca2ScOsO6 and Ca2.2Mg0.8OsO6 were synthesized in polycrystalline form utilizing the conventional solid-state method. The crystal structure of these compounds were characterized through X-ray diffraction, and magnetic properties were explored through magnetic susceptibility measurements. Employing the spin-dimer analysis method, relative magnetic exchange interactions were calculated and modeled. These novel osmium-based B-site ordered double perovskites were then compared to isostructural compounds to study the effects of the osmium oxidation state on crystal structure and the exhibited properties.

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Luo, Kun. "Cation ordered and anion-vacancy ordered perovskite materials." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:f36a3f97-70b1-4ab6-819b-d400341a4558.

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The investigation in this thesis focuses on the synthesis of cation-ordered perovskite phases by introducing anion vacancies into the structure. Complex cation-ordered phases Ba2YMO5 and Ba3YM2O7.5 (M = Fe, Co) have been synthesized using ceramic or citrate gel methods under flowing argon. Close inspection reveals that the structures are constructed from Y2M2O102 basic units which consist of two YO6 octahedra and two MO4 tetrahedra in a rock-salt type arrangement. In the structure of Ba2YMO5 (M = Fe, Co), the neighbouring Y2M2O102 units are connected with an equivalent one in the yz-plane with YO6 octahedra sharing an apex. In the structure of Ba3YM2O7.5 (M = Fe, Co), the basic units are connected to each other by the M2O7 dimers via a chain of Y – O – M – O – M – O – Y bonds. Complex cation ordering can be achieved by carefully controlling the anion vacancies and selecting the cations with different ionic radii. The anion vacancies present in Ba2YMO5 (M = Fe, Co) (space group P21/n) allow the intercalation of anions like O2- and F- into the lattice. The fluorination of Ba2YCoO5 leads to the formation of a new orthorhombic phase Ba2YCoO5F0.42 (space group Pbnm) in which the inserted fluoride ions are distributed in a disordered manner. In contrast, the topochemical oxidation of Ba2YFeO5 leads to the formation of a new orthorhombic phase Ba2YFeO5.5 (space group Pb21m), in which Fe4+ centres are located in 4-coordinate tetrahedral sites and 5-coordinate pyramidal sites, respectively. The polar structure of Ba2YFeO5.5 is confirmed by the observation of second-harmonic generation activity and pyroelectric behaviour. Ba2YFeO5.5 also exhibits a combination of ferromagnetic and antiferromagnetic behaviours at low temperature. LaCa2Fe2GaO8 adopts a six-layer structure consisting of an OOTLOOTR stacking sequence of layers of (Fe/Ga)O6 octahedra (O) and (Fe/Ga)O4 tetrahedra (T), related to that of the four-layer brownmillerite structure (space group Pbma). The chains of tetrahedra in the structure of LaCa2Fe2GaO8 exhibit a cooperative twisting distortion in which the twisting direction of the chains of tetrahedra alternates in adjacent tetrahedral layers. LaxSr2-xCoGaO5+δ (0.5 < x < 1) adopts brownmillerite structures which consist of octahedral and tetrahedral layers with mixed valence of Co2+/Co3+. The members with x = 0.5, 0.6 and 0.7 adopt structures with I2mb space group symmetry, in which all the tetrahedra twist in the same direction. The members with x = 0.8, 0.9 and 1.0 adopt structures with Imma space group symmetry, in which the chains of the tetrahedra twist in a disordered manner. A change in the Co3+ spin state from high spin (HS) to low spin (LS) is observed as the La/Sr ratio increases. The change of the Co3+ spin state can be rationalized on the basis of internal chemical pressure.
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Akizuki, Yasuhide. "High-Pressure Synthesis and Properties of Novel Perovskite Oxides." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199319.

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Tan, Chaou Choak. "Suppression of semiconductivity in the B-site ordered perovskite Ba2Bi3+Bi5+O6 by chemical doping." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.557621.

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An investigation on making a dielectric material from a Bi3+/Bi5+ charge transfer semiconducting Ba2Bi206 (BBO) compound by using Nb5+, Ta5+, Sb5+, La3+ and y 3+ cations to replace either Bi5+ or Bi3+ was conducted. The influence of the processing temperature on the electrical properties of BBO was investigated and then followed by dopant studies to establish the structure-composition-property relationships in doped BBO perovskites. BBO and Ba2Bi2-xMx06 (M = Nb5+, Ta5+, Sb5+, La3+, y3+) were synthesised at temperatures from 800-1100 °C using the mixed oxide method. Control of the processing temperatures and conditions are critical as they can influence Bi volatilisation, oxygen loss, a change in polymorphic phase transition temperatures and a loss of B-site cation ordering. All of these factors affect the dielectric properties. BBO adopts 121m symmetry at room temperature (RT) with a tolerance factor (t) of 0.927. t increases to near unity when doped with pentavalents cations and pentavalent doped BBO series show a change in RT crystal structure from J2lm to R3 when t ;;:=: 0.94. Trivalent doped BBO series show a more complex change in RT crystal structure with changes in sequence from triclinic to monoclinic to rhombohedral and finally to cubic. The change in RT crystal structure from a monoclinic to rhombohedral structure occurs at higher t (0.960) than the pentavalent doped BBO series and the rhombohedral structure exists under a very narrow window of tolerance factor (0.960 s::t < 0.962). BBO is a p-type semiconductor and the total resistivity of ceramics is dominated by the grain boundary component. The bulk resistivity increases when sintered at ;;:=:950 'C. The semiconductivity of BBO can be suppressed by either pentavalent or trivalent dopants. The reduction in conductivity can be ~ 4-7 orders of magnitude as observed in Nb-, Ta- and Y-doped BBO and the activation energy increases from ~ 0.1 eV from undoped BBO to ~ 0.6 eV for Nb- doped BBO. Pentavalent doped BBO compound show higher bulk relative permittivity compared to BBO and in particular, Nb-doped BBO shows the highest permittivity. The values are twice that expected based on the Clausius Mossotti equation.
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Ricciardo, Rebecca Ann. "Chemical, Magnetic, and Orbital Order of Polycrystalline and Thin film Double Perovskites." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250277883.

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Boseggia, S. "Magnetic order and excitations in perovskite iridates studied with resonant X-ray scattering techniques." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1459969/.

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Transition metal oxides containing a 5d element are increasingly attracting attention as an arena in which to search for novel electronic states. These are proposed to derive from the interplay between the strong spin-orbit interaction (SOI) in the 5ds, the electronic correlations and crystal field effects. Iridium based compounds have featured predominantly in this quest, with considerable focus on the layered perovskites in which a novel “spin-orbit induced” Mott-like insulating state emerges. In this case, the SOI leads to the jeff = 1/2 ground state for the Ir4+ (5d5) ions observed in Sr2IrO4. In this thesis I demonstrate that resonant X-ray scattering techniques at the Ir L edges are a valuable tool to investigate the electronic and magnetic properties of iridium oxides. In particular the evolution of the jeff = 1/2 state as a function of structural distortions in the single layer iridates Sr2IrO4 and Ba2IrO4, and as a function of the dimensionality in the bilayer Sr3Ir2O7 is investigated. My findings show that the magnetic and electronic structures in the single layered perovskites are remarkably robust to structural distortions. Conversely, adding an extra IrO6 layer (Sr2IrO4 →Sr3Ir2O7) the ground and excited states change dramatically. Both these phenomena can be linked directly to the unique three-dimensional character of the jeff = 1/2 state. Furthermore, the X-ray resonant scattering cross-section of Ir4+ at the L2,3 edges, calculated in a single-ion model, shows a non-trivial dependence on the direction of the magnetic moment, μ. These results provide important insights into the interpretation of X-ray data from the iridates, including that a jeff = 1/2 ground state cannot be assigned on the basis of L2/L3 intensity ratio alone.
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Santana, Marcos Cleison Silva. "Síntese e caracterização estrutural e magnética das perovskitas complexas ReFe0:5M0:5O3 (Re = Dy, Gd, Sm, Eu,Nd ; M= Mn,Al)." Universidade Federal de Sergipe, 2015. https://ri.ufs.br/handle/riufs/5280.

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Samples of Bi 2Fe4O9 mullite and ReFe 0.5M0.5O3 (Re = Nd, Sm, Eu, Gd, Dy; M = Mn, Al) complex perovskites were successfully synthesized by using the combustion synthesis method. While the mullite was obtained after thermal treatment at temperatures below 1000ºC, complex perovskites are produced after thermal treatments between 1250ºC and 1500ºC for at most 24 h. The X-ray diffraction data analysis suggests the formation of single phase orthorhombic structure, after suitable heat treatment. Scanning electron microscopy (SEM) revealed the formation of micrometric grain size, giving to the sample the relative density. EDS spectra confirmed the homogeneity and purity of complex perovskites. Magnetization measurements as a function of field and temperature showed the diversity of magnetic behavior of the samples. Among the behaviors we can highlight the reorientation of spin for ortoferritas ReFe0.5Mn0.5O3 (Re = Dy, Gd, Eu, Sm, Eu) and ReFe0.5Al0.5O3 (Re = Dy, Nd). Another interesting finding was the effect of magnetic reversal of the samples ReFe0.5Al0.5O3 (Re = Nd, Gd) and EuFe0.5Mn0.5O3. Raman spectra show anomalous bands of second order in the perovskite DyFe0.5Al0.5O3 with characteristics of resonant effects. The evolution of the band associated with the symmetric vibrational mode of the octahedron shows hardening at the temperature range of ordered magnetic phase, thus suggesting a possible spin-phonon coupling. Depolarization current measurements highlights a relaxation process due to charge carriers in the samples ReFe0.5Mn0.5O3 (Re = Dy, Gd). The application of magnetic field profoundly influences the depolarization current behavior of DyFe0.5Mn0.5O3. Dielectric permittivity measurements showed no anomalies between 10 K and 300 K, that could can be associated to a ferroelectric phase.
Amostras da mulita Bi2Fe4O9 e das perovskitas complexas ReFe0.5M0.5O3 (Re= Nd, Sm, Eu, Gd, Dy; M = Mn, Al) foram sintetizadas com sucesso utilizando o método de síntese por reação de combustão. Enquanto a mulita foi obtida após tratamento térmico com temperaturas abaixo de 1000ºC, as perovskitas complexas foram produzidas após tratamentos térmicos entre 1250ºC e 1500ºC por, no máximo, 24 h. A análise de dados de difração de raios X sugerem a formação de estruturas ortorrômbicas de fase única, após os tratamento térmico apropriado. Medidas de microscopia evidenciaram formação de grãos micrométricos conferindo às amostras relativa densidade. Os espectros EDS confirmaram a homogeneidade e pureza das perovskitas complexas. As medidas de magnetização em função do campo e da temperatura evidenciaram a diversidade de comportamentos magnéticos das amostras estudadas. Entre os comportamentos destacamos reorientação de spin para as ortoferritas ReFe0.5Mn0.5O3 (Re = Dy, Gd, Eu, Sm, Eu) e ReFe0.5Al0.5O3 (Re = Dy,Nd). Outro interessante achado foi o efeito de inversão magnética das amostras ReFe0.5Al0.5O3 (Re = Nd, Gd) e EuFe0.5Mn0.5O3. Espectros Raman demonstram bandas anômalas de segunda ordem na perovskita DyFe0.5Al0.5O3 com características de efeitos ressonantes. A evolução da banda associada ao modo vibracional simétrico do octaedro apresenta endurecimento em temperaturas na faixa da fase magnética ordenada, sugerindo assim, um possível acoplamento spin-f onon. Medidas de corrente de despolarização destaca um processo de relaxação devido aos portadores de cargas nas amostras ReFe0.5Mn0.5O3 (Re=Dy,Gd). A aplicação de campo magnético influencia profundamente o comportamento da corrente de despolarização do DyFe0.5Mn0.5O3. Medidas de permissividade dielétrica não exibiram anomalias entre 10 K e 300 K que possam a ser associadas a uma fase ferroelétrica.
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Papadopoulos, Konstantinos. "Investigation of magnetic order in nickel-5d transition metal systems." Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-383009.

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Double perovskite materials exhibit alterations in magnetic order through manipulation oftheir crystal structure. Certain ultra thin metallic bilayers can create an exotic magnetic stateof confined spin textures called skyrmions. In both cases, new atomic arrangements leadto new electrical and magnetic properties. The following work comprises two studies, bothof which examine the magnetic properties of transition metals in either powder or thin filmsamples. The first part is dedicated to a series of muon spin rotation and relaxation (muSR)experiments on a LaSrNiReO6, double perovskite, powder sample. In the muSR technique, aspin polarized muon beam is focused onto a powder envelope in low pressure and temperatureconditions. The spins of the implanted muons evolve depending on the intrinsic or externallyapplied magnetic field according to Larmor precession. The measurement is based onthe detection of decay positrons that carry this precession information on their preferreddecay directions. Measurements that were realized in wTF, ZF and LF setups, reveal asecond transition to magnetic order at Tc ≃ 22K, below a transition that was observed at T =261K from magnetic susceptibility measurements. The experimental results point to threemagnetic phases, paramagnetic for T > 261K, dilute ferrimagnetic for 22 < T < 261K and amagnetically ordered state for T < 22K, that may implicate ferro- and antiferromagnetismfrom Ni sublattices and Ni-Re interactions. The second part follows an attempt to produce and characterize ultra thin bilayer filmsfor the observation of interfacial chiral structures and skyrmions. Co/Fe/MgO (100) andW/Ni/Cu (100) bilayers were grown with magnetron sputter deposition in various layerthicknesses and their structure was determined by X-ray reflectometry (XRR). The XRRscans presented a relatively thick-layered Co/Fe/MgO film, while extremely thin and roughW/Ni/Cu bilayers, for the purposes of studying films with broken interfacial inversionsymmetry. This study was concluded with indicative magneto-transport measurements thatalso point to the reconfiguration of the growth procedure.
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Zuo, Peng. "Synthèses, études structurales et physiques de doubles pérovskites ordonnées NaLnCoWO6 : recherche de nouveaux composés multiferroïques basés sur la ferroélectricité hybride impropre." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI113/document.

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Ce travail porte sur la synthèse et la caractérisation de nouveaux matériaux multiferroïques basés sur le concept très récent de la Ferroélectricité Hybride Impropre.Deux classes de matériaux ont été envisagées : les oxydes de type Ruddlesden-Popper NaRMO4 (R=Y, La; M= Mn, Cr) et les doubles pérovskites ordonnées NaLnCoWO6 (Ln= Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Yb). Les essais de synthèse sur la première classe n’ont pas permis d’obtenir les composés visés. Pour la seconde classe, l’ensemble des composés ont pu être obtenus par synthèse par voie solide à haute température. Les composés NaLnCoWO6 (Ln=La, Pr, Nd) ont été synthétisés à pression ambiante. L’usage des techniques de Hautes Pressions – Hautes Températures (HP-HT) a permis de stabiliser les composés contenant des terres rares plus petites et d’obtenir ainsi neuf nouveaux composés aux propriétés inédites.L’utilisation combinée de la diffraction sur poudre des rayons X au synchrotron et des neutrons a permis une étude structurale fine de la famille des doubles pérovskites ordonnées NaLnCoWO6. Les groupes d’espace ont été déterminés grâce aux affinements Rietveld des diffractogrammes de Rayons X sur poudre haute résolution. Les composés NaLnCoWO6 (Ln=La, Pr, Nd) cristallisent dans le groupe d’espace centrosymétrique C2/m tandis que les 9 nouveaux composés (Ln= Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Yb) cristallisent dans le groupe d’espace polaire P21. Des mesures de génération de seconde harmonique confirment la structure non-centrosymétrique des nouveaux composés. L’analyse adaptée des modes de symétrie des composés cristallisant dans la structure polaire montre que l’amplitude du mode polaire induit augmente avec la diminution de la taille du cation Ln3+. La polarisation estimée à partir des affinements de la structure pourrait atteindre jusqu’à ~20µC/cm2.Une transition de phase présentant une très large hystérésis en température (~150K) a été observée par diffraction des neutrons pour le composé NaLaCoWO6. De plus, les images obtenues en Microscopie Electronique en Transmission révèlent la présence de bandes dans la phase haute température. Cette superstructure présente une périodicité de 12ap selon la direction [100]p ou [010]p . On a pu montrer à l’aide d’observations en STEM (microscopie à balayage en transmission) combinées avec des mesures en EELS (spectroscopie de pertes d’énergie des électrons) que ce contraste de bandes n’est pas lié à une variation de composition mais bien à une variation structurale. Différents modèles de rotations des octaèdres d’oxygènes ont été élaborés pour valider les données expérimentales obtenues par diffraction des rayons X et de neutrons. Le schéma de rotation qui décrit au mieux les données est a-a-c0. Concernant la phase basse température le groupe d’espace attribué est le groupe polaire P21.Les caractérisations magnétiques ont été réalisées pour toutes ces phases. Tous les composés NaLnCoWO6 s’ordonnent dans une configuration antiferromagnétique. Les températures de Néel varient entre 4 et 13K en fonction de la nature de la terre-rare. Les moments effectifs déterminés par la loi de Curie-Weiss sont en accord avec les moments théoriques attendus. Toutes les températures de Weiss sont négatives traduisant le fait que les interactions antiferromagnétiques sont prépondérantes dans ces systèmes. Les structures magnétiques ont été déterminées pour les composés Ln= Y, La, Tb, and Ho. Pour ces mêmes composés, des mesures diélectriques en fonction de la température et du champ magnétique ont permis de mettre en évidence un couplage magnéto-diélectrique conséquent pour Ln=Y and Ho. Les mesures de courant pyroélectrique autour de la transition magnétique montrent qu’il existe une polarisation induite par l’ordre magnétique dans le composé NaYCoWO6.. C’est la première mise en évidence expérimentale d’un couplage magnéto-électrique dans la famille des doubles pérovskites ordonnées AA’BB’O6
In this study, new magneto-electric materials were synthesized on the basis of the very recently recognized ferroelectric inducing mechanism, hybrid improper ferroelectricity, and structural and physical properties characterizations were carried out on these new phases.Two classes of materials were focused on: the Ruddlesden-Popper oxides NaRMO4 (R=Y, La; M= Mn, Cr) and the doubly ordered perovskites NaLnCoWO6 (Ln= Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Yb). Attempts to synthesize the former class failed to give the target phases. All compounds in the latter class were prepared successfully by solid-state reactions at high temperature, among which the compounds NaLnCoWO6 (Ln=La, Pr, Nd) were prepared at ambient pressure while the other nine compounds were synthesized at high pressure.The structural study of the doubly ordered perovskite family NaLnCoWO6 was performed by synchrotron X-ray powder diffraction (SXRPD) and neutron powder diffraction (NPD). Based on the Rietveld refinement of the SXRPD patterns, the space groups were assigned. NaLnCoWO6 (Ln=La, Pr, Nd) compounds crystallize in the centrosymmetric C2/m symmetry, whereas the other nine new compounds crystallize in the polar space group P21. Second harmonic generation measurements on powder confirmed the non-centrosymmetric structure of the new compounds. Symmetry mode analysis demonstrates that the amplitude of the induced polar mode increases with a decreasing Ln cation size. The amplitude of the polarization was estimated from the refined structures, and can be as large as ~20µC/cm2.A structural phase transition was observed by NPD in NaLaCoWO6 with a large temperature hysteresis of ~150K. In addition, stripes were observed on the high-resolution transmission electron microscopy (TEM) images in the high temperature phase. The periodicity of this superstructure is 12ap along either the [100]p or [010]p direction. Further investigations by scanning TEM and electron energy loss spectroscopy revealed that the contrast of the stripes is due to a structural modulation rather than a compositional variation. Octahedral tilt twinning models were built with different tilting schemes to fit the observed SXRPD and NPD patterns. The tilting scheme a-a-c0 describes successfully the data. The low temperature phase was unambiguously determined to possess the polar space group P21.Magnetic and electric properties were experimentally characterized. All NaLnCoWO6 compounds order antiferromagnetically below TN which is between 4 and 13K. Curie-Weill fits were performed for all compounds, yielding reasonable effective magnetic moments compared to the theoretical ones. Weiss temperatures were all determined to be negative further indicating that antiferromagnetic interactions are dominant in these systems. Magnetic structures were determined for four NaLnCoWO6 (Ln= Y, La, Tb, and Ho) compounds, of which two have non-magnetic Ln cations (Y and La) and two have magnetic ones (Tb and Ho). Magneto-dielectric coupling was experimentally observed in compounds NaLnCoWO6 (Ln=Y, Tb, Ho) by dielectric measurements as a function of temperature and magnetic field. Polarization was derived for the Y and Ho compounds from pyroelectric current measurement, however, only the NaYCoWO6 compound demonstrates a polar behavior which cannot be switched. This is the first evidence that electric polarization can be induced by the magnetic ordering in the AA’BB’O6 class materials
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Books on the topic "Ordered perovskites"

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Zhang, H. Mesoscopic Structures and Their Effects on High-Tc Superconductivity. Edited by A. V. Narlikar. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780198738169.013.12.

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This article presents the results of model calculations carried out to determine the mesoscopic structural features of high-temperature superconducting (HTS) crystal structures, and especially their characteristic high critical temperature (Tc) and anisotropy. The crystal structure of high-temperature superconductors (HTSc) is unique in having some mesoscopic features. For example, the structures of a majority of cuprite superconductors are comprised of two structural blocks, perovskite and rock salt, stacked along the c-direction. This article calculates the interaction between the perovskite and rock salt blocks in the form of combinative energy in order to elucidate the effects of mesoscopic structures on high-Tc superconductivity. Both X-ray diffraction and Raman spectroscopy show that a ‘fixed triangle’ exists in the samples under investigation. The article also examines the importance of electron–phonon coupling in high-Tc superconductors.
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Book chapters on the topic "Ordered perovskites"

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Kundu, Asish K. "Ordered-Disordered Perovskite Cobaltites." In Magnetic Perovskites, 73–103. New Delhi: Springer India, 2016. http://dx.doi.org/10.1007/978-81-322-2761-8_3.

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Ganose, Alex. "Vacancy-Ordered Double Perovskites." In Springer Theses, 87–106. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-55708-9_6.

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Sadakane, Masahiro, and Wataru Ueda. "Three-Dimensionally Ordered Macroporous (3DOM) Perovskite Mixed Metal Oxides." In Perovskites and Related Mixed Oxides, 113–42. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2015. http://dx.doi.org/10.1002/9783527686605.ch06.

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Tabata, Hitoshi. "Relaxor Superlattices: Artificial Control of the Ordered–Disordered State of B-Site Ions in Perovskites." In Topics in Applied Physics, 161–75. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/978-3-540-31479-0_9.

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Blinc, Robert. "Order and Disorder in Perovskites and Relaxor Ferroelectrics." In Structure and Bonding, 51–67. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/430_2006_050.

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Alonso, J. A., and I. Rasines. "On the Influence of the Non-Bonded Pair of Pb(II) in the Novel Ordered Perovskite Pb[Sc0.5(Ti0.25,Te0.25)]O3." In Chemical Crystallography with Pulsed Neutrons and Synchroton X-rays, 577–78. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-4027-7_33.

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Nakamura, Shin, Akio Fuwa, and Yorihiko Tsunoda. "Observation of the charge order in perovskite manganite Pr 0.5 Ca 0.5 MnO 3 by Mössbauer quadrupole effect." In ICAME 2011, 609–12. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-4762-3_104.

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Kumar Singh, Manoj, Pratik V. Shinde, Pratap Singh, and Pawan Kumar Tyagi. "Two-Dimensional Materials for Advanced Solar Cells." In Solar Cells - Theory, Materials and Recent Advances. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.94114.

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Inorganic crystalline silicon solar cells account for more than 90% of the market despite a recent surge in research efforts to develop new architectures and materials such as organics and perovskites. The reason why most commercial solar cells are using crystalline silicon as the absorber layer include long-term stability, the abundance of silicone, relatively low manufacturing costs, ability for doping by other elements, and native oxide passivation layer. However, the indirect band gap nature of crystalline silicon makes it a poor light emitter, limiting its solar conversion efficiency. For instance, compared to the extraordinary high light absorption coefficient of perovskites, silicon requires 1000 times more material to absorb the same amount of sunlight. In order to reduce the cost per watt and improve watt per gram utilization of future generations of solar cells, reducing the active absorber thickness is a key design requirement. This is where novel two-dimensional (2d) materials like graphene, MoS2 come into play because they could lead to thinner, lightweight and flexible solar cells. In this chapter, we aim to follow up on the most important and novel developments that have been recently reported on solar cells. Section-2 is devoted to the properties, synthesis techniques of different 2d materials like graphene, TMDs, and perovskites. In the next section-3, various types of photovoltaic cells, 2d Schottky, 2d homojunction, and 2d heterojunction have been described. Systematic development to enhance the PCE with recent techniques has been discussed in section-4. Also, 2d Ruddlesden-Popper perovskite explained briefly. New developments in the field of the solar cell via upconversion and downconversion processes are illustrated and described in section-5. The next section is dedicated to the recent developments and challenges in the fabrication of 2d photovoltaic cells, additionally with various applications. Finally, we will also address future directions yet to be explored for enhancing the performance of solar cells.
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RAO, C. N. R., J. GOPALAKRISHNAN, and K. VIDYASAGAR. "Superstructures, Ordered Defects & Nonstoichiometry in Metal Oxides of Perovskite & Related Structures." In Solid State Chemistry, 275–94. WORLD SCIENTIFIC, 1995. http://dx.doi.org/10.1142/9789812795892_0021.

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RAO, C. N. R., J. GOPALAKRISHNAN, and K. VIDYASAGAR. "Superstructures, Ordered Defects & Nonstoichiometry in Metal Oxides of Perovskite & Related Structures." In Trends in Chemistry of Materials, 38–57. Co-Published with Indian Institute of Science (IISc), Bangalore, India, 2008. http://dx.doi.org/10.1142/9789812833846_0003.

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Conference papers on the topic "Ordered perovskites"

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Sugiyama, Jun, Hiroshi Nozaki, Izumi Umegaki, Wataru Higemoto, Masahiko Isobe, Hidenori Takagi, Hiroya Sakurai, et al. "A-site Ordered Chromium Perovskites, ACu3Cr4O12 with A = Trivalent Ions." In Proceedings of the 14th International Conference on Muon Spin Rotation, Relaxation and Resonance (μSR2017). Journal of the Physical Society of Japan, 2018. http://dx.doi.org/10.7566/jpscp.21.011009.

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Bartram, Ralph H. "PRESSURE AND TEMPERATURE DEPENDENCE OF CHROMIUM PHOTOLUMINESCENCE IN ORDERED PEROVSKITES." In Advanced Solid State Lasers. Washington, D.C.: OSA, 1985. http://dx.doi.org/10.1364/assl.1985.tha5.

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Bartram, Ralph H. "THERMAL QUENCHING OF CHROMIUM PHOTOLUMINESCENCE IN ORDERED PEROVSKITES AT HIGH PRESSURE." In Advanced Solid State Lasers. Washington, D.C.: OSA, 1987. http://dx.doi.org/10.1364/assl.1987.md1.

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Sreedevi, P. D., and P. Ravindran. "Revealing the optoelectronic properties of tin-based vacancy ordered double perovskites: K2SnBr6 and Rb2SnBr6." In NATIONAL CONFERENCE ON PHYSICS AND CHEMISTRY OF MATERIALS: NCPCM2020. AIP Publishing, 2021. http://dx.doi.org/10.1063/5.0061126.

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Choy, Wallace, and Jian Mao. "Solution-based and Microfabrication-free Approach to Form Ordered Nanostructured Perovskites for Photovoltaic and LED Applications." In 10th International Conference on Hybrid and Organic Photovoltaics. Valencia: Fundació Scito, 2018. http://dx.doi.org/10.29363/nanoge.hopv.2018.117.

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Eglitis, R. I., V. S. Vikhnin, P. A. Markovin, and G. Borstel. "Self-ordered second-component clusters in solid solutions on the basis of ferroelectric perovskites: Nb clusters in KTaO[sub 3]." In The 5th Williamsburg workshop on first-principles calculations for ferroelectrics. AIP, 1998. http://dx.doi.org/10.1063/1.56284.

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Ray, Rajyavardhan, A. K. Himanshu, Kumar Brajesh, B. K. Choudhary, S. K. Bandyopadhyay, Pintu Sen, Uday Kumar, and T. P. Sinha. "Electronic structure of ordered double perovskite Ba2CoWO6." In SOLID STATE PHYSICS: Proceedings of the 58th DAE Solid State Physics Symposium 2013. AIP Publishing LLC, 2014. http://dx.doi.org/10.1063/1.4872887.

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Masud, Md G., Arijit Ghosh, Jhuma Sannigrahi, and B. K. Chaudhuri. "Metal-semiconductor transition and ferroelectricity in charge ordered La0.5Ba0.5FeO3 perovskite." In SOLID STATE PHYSICS: Proceedings of the 56th DAE Solid State Physics Symposium 2011. AIP, 2012. http://dx.doi.org/10.1063/1.4710324.

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Mir, Shabir Ahmad, S. Yousuf, T. M. Bhat, S. Singh, Ab Q. Seh, Saveer A. Khandy, S. A. Sofi, Z. Saleem, and D. C. Gupta. "Structural and elasto-mechanical properties of ordered double perovskite Ba2LuSbO6." In DAE SOLID STATE PHYSICS SYMPOSIUM 2018. AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5113176.

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Kumar, Dhirendra, Satish Kumar, and V. G. Sathe. "Raman studies of ordered double perovskite thin film at high temperatures." In NANOFORUM 2014. AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4918239.

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