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Journal articles on the topic 'Bulk Stoichiometry'

Author: Grafiati

Published: 4 June 2021

Last updated: 15 February 2022

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1

Yu, Jianguo, Billy Valderrama, Hunter B. Henderson, Michele V. Manuel, and Todd Allen. "Near Surface Stoichiometry in UO2: A Density Functional Theory Study." Journal of Chemistry 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/142510.

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The mechanisms of oxygen stoichiometry variation in UO2at different temperature and oxygen partial pressure are important for understanding the dynamics of microstructure in these crystals. However, very limited experimental studies have been performed to understand the atomic structure of UO2near surface and defect effects of near surface on stoichiometry in which the system can exchange atoms with the external reservoir. In this study, the near (110) surface relaxation and stoichiometry in UO2have been studied with density functional theory (DFT) calculations. On the basis of the point-defect model (PDM), a general expression for the near surface stoichiometric variation is derived by using DFT total-energy calculations and atomistic thermodynamics, in an attempt to pin down the mechanisms of oxygen exchange between the gas environment and defected UO2. By using the derived expression, it is observed that, under poor oxygen conditions, the stoichiometry of near surface is switched from hyperstoichiometric at 300 K with a depth around 3 nm to near-stoichiometric at 1000 K and hypostoichiometric at 2000 K. Furthermore, at very poor oxygen concentrations and high temperatures, our results also suggest that the bulk of the UO2prefers to be hypostoichiometric, although the surface is near-stoichiometric.

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2

Zappettini, A., N. Spano, M. Mazzera, G. M. Guadalupi, and C. Paorici. "Off-stoichiometry determination of II–VI bulk crystals." Journal of Crystal Growth 310, no. 7-9 (April 2008): 2080–84. http://dx.doi.org/10.1016/j.jcrysgro.2007.11.232.

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3

Andersson, L. Mattias, Fengling Zhang, and Olle Inganäs. "Stoichiometry, mobility, and performance in bulk heterojunction solar cells." Applied Physics Letters 91, no. 7 (August 13, 2007): 071108. http://dx.doi.org/10.1063/1.2771524.

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4

Schirber, J. E., B. Morosin, R. M. Merrill, P. F. Hlava, E. L. Venturini, J. F. Kwak, P. J. Nigrey, R. J. Baughman, and D. S. Ginley. "Stoichiometry of bulk superconducting La2CuO4+δ: A superconducting superoxide?" Physica C: Superconductivity 152, no. 1 (March 1988): 121–23. http://dx.doi.org/10.1016/0921-4534(88)90081-0.

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5

Kogut, Iurii, Alexander Wollbrink, Carsten Steiner, Hendrik Wulfmeier, Fatima-Ezzahrae El Azzouzi, Ralf Moos, and Holger Fritze. "Linking the Electrical Conductivity and Non-Stoichiometry of Thin Film Ce1−xZrxO2−δ by a Resonant Nanobalance Approach." Materials 14, no. 4 (February 5, 2021): 748. http://dx.doi.org/10.3390/ma14040748.

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Bulk ceria-zirconia solid solutions (Ce1−xZrxO2−δ, CZO) are highly suited for application as oxygen storage materials in automotive three-way catalytic converters (TWC) due to the high levels of achievable oxygen non-stoichiometry δ. In thin film CZO, the oxygen storage properties are expected to be further enhanced. The present study addresses this aspect. CZO thin films with 0 ≤ x ≤ 1 were investigated. A unique nano-thermogravimetric method for thin films that is based on the resonant nanobalance approach for high-temperature characterization of oxygen non-stoichiometry in CZO was implemented. The high-temperature electrical conductivity and the non-stoichiometry δ of CZO were measured under oxygen partial pressures pO2 in the range of 10−24–0.2 bar. Markedly enhanced reducibility and electronic conductivity of CeO2-ZrO2 as compared to CeO2−δ and ZrO2 were observed. A comparison of temperature- and pO2-dependences of the non-stoichiometry of thin films with literature data for bulk Ce1−xZrxO2−δ shows enhanced reducibility in the former. The maximum conductivity was found for Ce0.8Zr0.2O2−δ, whereas Ce0.5Zr0.5O2-δ showed the highest non-stoichiometry, yielding δ = 0.16 at 900 °C and pO2 of 10−14 bar. The defect interactions in Ce1−xZrxO2−δ are analyzed in the framework of defect models for ceria and zirconia.

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6

Shim, Y., S. Horikawa, Y. Kikuno, and N. Yamamoto. "Growth and stoichiometry of THM-bulk single crystals of CuAlSe2." Journal of Crystal Growth 234, no. 1 (January 2002): 190–96. http://dx.doi.org/10.1016/s0022-0248(01)01672-4.

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7

Nedeltcheva, T., and L. Vladimirova. "Spectrophotometric determination of oxygen stoichiometry in YBCO superconducting bulk samples." Analytica Chimica Acta 437, no. 2 (June 2001): 259–63. http://dx.doi.org/10.1016/s0003-2670(01)01002-9.

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8

Schieber, M., M. Roth, H. Yao, M. DeVries, R. B. James, and M. Goorsky. "Bulk and surface stoichiometry of vapor grown mercuric iodide crystals." Journal of Crystal Growth 146, no. 1-4 (January 1995): 15–22. http://dx.doi.org/10.1016/0022-0248(94)00572-9.

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9

Bishop, S. R., K. L. Duncan, and E. D. Wachsman. "Surface and bulk oxygen non-stoichiometry and bulk chemical expansion in gadolinium-doped cerium oxide." Acta Materialia 57, no. 12 (July 2009): 3596–605. http://dx.doi.org/10.1016/j.actamat.2009.04.017.

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10

SONG, WEI, JING LU, ZHENGXIANG GAO, MING NI, LUNHUI GUAN, ZUJIN SHI, ZHENNAN GU, et al. "STRUCTURAL AND ELECTRONIC PROPERTIES OF ONE DIMENSIONAL KxC60 CRYSTAL ENCAPSULATED IN CARBON NANOTUBE." International Journal of Modern Physics B 21, no. 10 (April 20, 2007): 1705–14. http://dx.doi.org/10.1142/s0217979207036953.

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The structural and electronic properties of potential one dimensional (1D) superconductor — K x C 60 chain encapsulated inside a single-walled carbon nanotube is studied using first principles calculations. The stoichiometry of K to C 60 of the 1D K x C 60 crystal can reach 9, in contrast to a maximal stoichiometry of 6 found in the K doped bulk fullerides. The K 4s electrons are completely ionized, and fill chiefly the C 60-derived bands in a nonrigid way. The density of states at the Fermi level of the encapsulated 1D K x C 60 crystal is comparable to that in K doped bulk fullerides.

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11

McAuliffe, Rebecca D., and Daniel P. Shoemaker. "Inflexible stoichiometry in bulk pyrite FeS2 as viewed by in situ and high-resolution X-ray diffraction." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 74, no. 5 (August 24, 2018): 436–44. http://dx.doi.org/10.1107/s2052520618010144.

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Non-stoichiometry is considered to be one of the main problems limiting iron pyrite, FeS2, as a photovoltaic absorber material. Although some historical diffraction experiments have implied a large solubility range of FeS2−δ with δ up to 0.25, the current consensus based on calculated formation energies of intrinsic defects has lent support to line-compound behavior. Here it is shown that pyrite stoichiometry is relatively inflexible in both reductive conditions and in autogenous sulfur partial pressure, which produces samples with precise stoichiometry of FeS2 even at different Fe/S ratios. By properly standardizing in situ gas-flow X-ray diffraction measurements, no significant changes in the lattice parameter of FeS2 can be resolved, which portrays iron pyrite as prone to forming sulfur-deficient compounds, but not intrinsic defects in the manner of NiS2−δ.

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12

Diko, Pavel, Xavier Chaud, Vitaliy Antal, Mária Kaňuchová, Martina Šefčíková, Dušan Šuster, and Jozef Kováč. "Elimination of Oxygenation Cracking in YBCO Bulk Superconductors." Key Engineering Materials 409 (March 2009): 216–22. http://dx.doi.org/10.4028/www.scientific.net/kem.409.216.

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The reasons for cracking of YBa2Cu3Oδ/Y2BaCuO5 (Y123/Y211 or YBCO) bulk single-grain superconductors are mechanical stresses, which arise in the sample during its fabrication. Two main sources of stresses appearing during fabrication were identified: the different thermal expansion coefficients of 123 and 211 phases and the dependence of 123 phase lattice parameters on the oxygen stoichiometry. As-grown YBCO bulks have low oxygen content, YBa2Cu3O6.3, are not superconducting, and must be oxygenated to form YBa2Cu3O7. During standard oxygenation at 400 °C the shortening of crystal lattice parameters causes intensive cracking. The created cracks allow oxygen penetration into the bulk and cause the oxygenation time to be technologically acceptable but reduce significantly the superconducting properties. Here we show that it is possible to eliminate the formation of oxygenation cracks and to reach a critical current density 2.5 times higher than in material bulk oxygenated in a standard way. The oxygenated crack-free samples were obtained by high pressure oxygenation with progressively increasing oxygen partial pressure.

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13

Kulagin, N. A., L. A. Goroshkova, and Е. Hieckmann. "Change in properties of nano and bulk SrTiO3 crystals." Canadian Journal of Physics 90, no. 7 (July 2012): 683–91. http://dx.doi.org/10.1139/p2012-068.

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This paper describes selected properties of pure and doped strontium titanate single crystals. Data obtained using optical and cathode-luminescence, X-ray fluorescence, scanning electron microscope measurements of the crystals over plasma treatment, and crystallographic structure related oxidation state of the component and doped ions have been analyzed too. Colour centres in near stoichiometry crystals, quasi-ordered structures of nano-scale size pyramids generated by plasma flow on the surface, and ordered oxygen vacancy structures in the samples are presented in this paper.

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14

Qi, Kaibin, Xueyong Pang, Bing Yang, and Weikai Bao. "Soil carbon, nitrogen and phosphorus ecological stoichiometry shifts with tree species in subalpine plantations." PeerJ 8 (October 12, 2020): e9702. http://dx.doi.org/10.7717/peerj.9702.

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Understanding ecological stoichiometric characteristics of soil nutrient elements, such as carbon (C), nitrogen (N) and phosphorus (P) is crucial to guide ecological restoration of plantations in ecologically vulnerable areas, such as alpine and subalpine regions. However, there has been only a few related studies, and thus whether and how different tree species would affect soil C:N:P ecological stoichiometry remains unclear. We compared soil C:N:P ecological stoichiometry of Pinus tabulaeformis, Larix kaempferi and Cercidiphyllum japonicum to primary shrubland in a subalpine region. We observed strong tree-specific and depth-dependent effects on soil C:N:P stoichiometry in subalpine plantations. In general, the C:N, C:P and N:P of topsoil (0–10 cm) are higher than subsoil (>10 cm) layer at 0–30 cm depth profiles. The differences in C:N, N:P and C:P at the topsoil across target tree species were significantly linked to standing litter stock, tree biomass/total aboveground biomass and Margalef’s index of plant community, respectively, whereas the observed variations of C:N, N:P and C:P ratio among soil profiles are closely related to differences in soil bulk density, soil moisture, the quantity and quality of aboveground litter inputs as well as underground fine root across plantations examined. Our results highlight that soil nutrients in plantation depend on litter quantity and quality of selected tree species as well as soil physical attributes. Therefore, matching site with trees is crucial to enhance ecological functioning in degraded regions resulting from human activity.

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15

Geohegan, D. B., D. N. Mashburn, R. J. Culbertson, S. J. Pennycook, J. D. Budai, R. E. Valiga, B. C. Sales, et al. "Pulsed laser deposition of thin superconducting films of Ho1Ba2Cu3O7 − x and Y1Ba2Cu3O7 − x." Journal of Materials Research 3, no. 6 (December 1988): 1169–79. http://dx.doi.org/10.1557/jmr.1988.1169.

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Thin films of Ho1Ba2Cu3O7 − x and Y1Ba2Cu3O7 − x were deposited on SrTiO3 and Al2O3, substrates by pulsed laser deposition of high-Tc bulk superconductor pellets in vacuum. Following annealing in O2 at 800–900 °C the films were superconducting with typical Tc (50%) = 89 K and transition widths of 10 K. Rutherford backscattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS) were utilized to study the stoichiometry of the as-deposited films for laser energy, densities between 0.11 and 4.5 J cm−2. The films were deficient in holmium and yttrium for energy densities below 0.6 and 0.4 J cm −2, respectively. The films were stoichiometric for fluences above 0.6 J cm−2. In addition, preliminary time dependence and spectroscopic observations of the laser-produced plasma are presented. The results indicate an ablation mechanism that at high energy densities preserves stoichiometry. TEM and x-ray characterization of annealed, superconducting Ho1Ba2Cu3O7 − x films on (100) SrTiO3 showed mixed regions of epitaxially oriented 1:2:3 material with either the c axis or a axis oriented along the surface normal. The a-axis-oriented material grew preferentially in the films with b, c, twinning.

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16

Khushaim, Muna, Torben Boll, Judith Seibert, Ferdinand Haider, and Talaat Al-Kassab. "Characterization of Precipitation in Al-Li Alloy AA2195 by means of Atom Probe Tomography and Transmission Electron Microscopy." Advances in Condensed Matter Physics 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/647468.

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The microstructure of the commercial alloy AA2195 was investigated on the nanoscale after conducting T8 tempering. This particular thermomechanical treatment of the specimen resulted in the formation of platelet-shapedT1Al2CuLi/θ′Al2Cuprecipitates within the Al matrix. The electrochemically prepared samples were analyzed by scanning transmission electron microscopy and atom probe tomography for chemical mapping. Theθ′platelets, which are less than 2 nm thick, have the stoichiometric composition consistent with the expected Al2Cu equilibrium composition. Additionally, the Li distribution inside theθ′platelets was found to equal the same value as in the matrix. The equally thinT1platelet deviates from the formula (Al2CuLi) in its stoichiometry and shows Mg enrichment inside the platelet without any indication of a higher segregation level at the precipitate/matrix interface. The deviation from the (Al2CuLi) stoichiometry cannot be simply interpreted as a consequence of artifacts when measuring the Cu and Li concentrations inside theT1platelet. The results show rather a strong hint for a true lower Li and Cu contents, hence supporting reasonably the hypothesis that the real chemical composition for the thinT1platelet in the T8 tempering condition differs from the equilibrium composition of the thermodynamic stable bulk phase.

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17

Stoyanova-Ivanova, Angelina, Tsvetanka Nedeltcheva, and Latinka Vladimirova. "Spectrophotometric determination of oxygen content in calcium substituted RBCO (R=Eu, Gd, Er) superconductors." Open Chemistry 3, no. 3 (September 1, 2005): 432–40. http://dx.doi.org/10.2478/bf02479273.

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AbstractThe oxygen stoichiometry in R1−x CaxBa2Cu3Oy (R=Eu, Er, Gd; x=0, 0.2, 0.25, 0.3) superconducting bulk samples was determined spectrophotometrically. The dependence of the critical temperature on the y-oxygen coefficient and the x-coefficient of the included calcium was studied.

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18

Medvedkin, G. A., and M. A. Magomedov. "Polycrystalline Bulk CuInSe₂ with a Deviation from Valence Stoichiometry." Solid State Phenomena 67-68 (April 1999): 385–90. http://dx.doi.org/10.4028/www.scientific.net/ssp.67-68.385.

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19

Dai, Xiaoqin, Xiaoli Fu, Liang Kou, Huimin Wang, and Clinton C. Shock. "C:N:P stoichiometry of rhizosphere soils differed significantly among overstory trees and understory shrubs in plantations in subtropical China." Canadian Journal of Forest Research 48, no. 11 (November 2018): 1398–405. http://dx.doi.org/10.1139/cjfr-2018-0095.

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Rhizosphere soil C:N:P stoichiometry is useful for identifying the linkage of plant species and soil nutrients, which can be particularly helpful for understory vegetation management of forest ecosystems. There has been limited research on rhizosphere soil stoichiometry, especially for co-existing overstory and understory plant species. We investigated the bulk and rhizosphere soil C:N:P stoichiometry of dominant overstory trees and understory shrubs (Adinandra millettii, Eurya muricata, and Loropetalum chinense) in Pinus massoniana Lamb., Pinus elliottii Engelm., and Cunninghamia lanceolata (Lamb.) Hook. plantations in subtropical China. Rhizosphere soil C, N, and P concentrations and ratios increased significantly compared with bulk soil, and those of overstory trees were higher than those of understory shrubs with the exception of L. chinense. Rhizosphere soil C:N, C:P, and N:P of L. chinense were not significantly different with those of overstory trees but were higher than those of A. millettii and E. muricata. Soil pH significantly influenced the profiles produced by soil C, N, and P concentrations and their stoichiometries. This study indicated that the difference in nutrient status between overstory trees and understory shrubs was related to shrub species, in which soil pH was the dominant driving factor. Understory shrub species should be considered in plantation management to reduce resource competition among species.

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20

Dehkordi, Arash Mehdizadeh, Sriparna Bhattacharya, Taghi Darroudi, Mehmet Karakaya, Courtney Kucera, John Ballato, Rasheed Adebisi, et al. "Optimizing thermal conduction in bulk polycrystalline SrTiO3−δ ceramics via oxygen non-stoichiometry." MRS Communications 8, no. 04 (November 14, 2018): 1470–76. http://dx.doi.org/10.1557/mrc.2018.220.

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21

Markov, A. V., V. I. Biberin, A. Y. Polyakov, N. B. Smirnov, A. V. Govorkov, V. N. Gavrin, A. V. Kalikhov, J. P. Kozlova, E. P. Veretenkin, and T. J. Bowles. "Synthesis solute diffusion growth of bulk GaAs: Effects of growth temperature and stoichiometry." Solid-State Electronics 51, no. 7 (July 2007): 1039–46. http://dx.doi.org/10.1016/j.sse.2007.05.005.

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22

Lanford, W. A., and B. Abeles. "Use of superlattices to determine bulk and interface stoichiometry of very thin films." Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 15, no. 1-6 (April 1986): 390–93. http://dx.doi.org/10.1016/0168-583x(86)90328-9.

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23

Alexander, K. B., R. K. Williams, and S. J. Pennycook. "Stacking variations in bulk Y2Ba4Cu8O16 materials." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 4 (August 1990): 106–7. http://dx.doi.org/10.1017/s0424820100173662.

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The structure and properties of the Y2Ba4Cu6+nO14+n (n = 0,1,2) series of high temperature superconducting materials have recently been examined. The structural difference between these materials is the number of planes containing Cu-O chains that exist between the Ba-O layers. In YBa2Cu3O7−x (123), a single plane of Cu-O is observed, whereas in Y2Ba4Cu8O16 (124) two planes of Cu-O are present and result in a double square planar chain along the b-axis (Fig. 1). In the Y2Ba4Cu7O15 (247) structure, alternate single and double planes of Cu-O chains are observed. The advantages of the 124 materials are that the tetragonal-to-orthorhombic transformation observed in 123 materials does not occur and the difference between the a and b lattice parameters is one-half that of the 123 materials. It has also been reported that the oxygen stoichiometry is stable, probably due to the fact that the oxygen atoms in the double chains are bonded to three rather than two copper atoms. High oxygen pressures must be used to fabricate 124 in bulk form. Superconducting temperatures (Tc) up to approximately 90K have been observed in 124 materials with calcium additions.

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24

Novak, Travis G., Jin Kim, Paul A. DeSario, and Seokwoo Jeon. "Synthesis and applications of WO3 nanosheets: the importance of phase, stoichiometry, and aspect ratio." Nanoscale Advances 3, no. 18 (2021): 5166–82. http://dx.doi.org/10.1039/d1na00384d.

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WO3 nanosheets, which can be synthesized through a wide variety of both bottom-up and top-down methods, can achieve better performance than bulk WO3 in many catalytic, sensing, electrochromic, and charge storage applications.

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25

Polyakov, A. Y., Mark A. Fanton, Marek Skowronski, Hun Jae Chung, Saurav Nigam, and Sung Wook Huh. "Halide-CVD Growth of Bulk SiC Crystals." Materials Science Forum 527-529 (October 2006): 21–26. http://dx.doi.org/10.4028/www.scientific.net/msf.527-529.21.

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A novel approach to the high growth rate Chemical Vapor Deposition of SiC is described. The Halide Chemical Vapor Deposition (HCVD) method uses SiCl4, C3H8 (or CH4), and hydrogen as reactants. The use of halogenated Si source and of separate injection of Si and C precursors allows for preheating of source gases without causing premature chemical reactions. The stoichiometry of HCVD crystals can be controlled by changing the C/Si flow ratio and can be kept constant throughout growth, in contrast to the Physical Vapor Transport technique. HCVD was demonstrated to deposit high crystalline quality, very high purity 4H- and 6H-SiC crystals with growth rates comparable to other bulk SiC growth techniques. The densities of deep electron and hole traps are determined by growth temperature and C/Si ratio and can be as low as that found in standard silane-based CVD epitaxy. At high C/Si flow ratio, the resistivity of HCVD crystals exceeds 105 _cm. These characteristics make HCVD an attractive method to grow SiC for applications in high-frequency and/or high voltage devices.

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26

Qiao, Yajun, Wen Yang, Yuxuan Zhao, Nasreen Jeelani, Lingqian Xu, Hui Zhao, Yanan Zhang, Shuqing An, and Xin Leng. "How Spartina alterniflora adapts to a new environment created by embankment reclamation through C-N-P stoichiometry in the coastal wetlands of eastern China." Marine and Freshwater Research 69, no. 5 (2018): 823. http://dx.doi.org/10.1071/mf17374.

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Although embankment reclamation is a recurring activity in the coastal wetlands of China, the effect of embankment construction on plant growth has attracted little attention. Leaf carbon, nitrogen and phosphorus stoichiometry (C-N-P stoichiometry) of a plant can be used to reflect plant adaptation to new environments created by reclamation. In the present study we investigated the biomass and leaf C-N-P stoichiometry of Spartina alterniflora Loisel., soil C-N-P stoichiometry and soil moisture, salinity, bulk density and pH in both embankment-reclaimed and natural S. alterniflora salt marshes in eastern China. Plant biomass, leaf P content, soil salinity and soil moisture were significantly lower in the reclaimed compared with natural marsh. The decrease in leaf P content is possibly attributed to changes in soil salinity, soil moisture and soil organic C and N content in the reclaimed marsh. The results of the present study indicate that the decreased aboveground biomass in the reclaimed marsh is likely to be correlated with an increase in the leaf N:P ratio, in accordance with the ‘growth rate hypothesis’. However, previously published threshold values of the N:P ratio as indicators of N or P limitation of plant growth may not be applicable to S. alterniflora at our study site.

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27

Ding, Leilei, Puchang Wang, Wen Zhang, Yu Zhang, Shige Li, Xin Wei, Xi Chen, Yujun Zhang, and Fuli Yang. "Shrub Encroachment Shapes Soil Nutrient Concentration, Stoichiometry and Carbon Storage in an Abandoned Subalpine Grassland." Sustainability 11, no. 6 (March 22, 2019): 1732. http://dx.doi.org/10.3390/su11061732.

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Soil nutrient stoichiometry plays a substantial role in terrestrial carbon and nutrient cycling. However, the changes in soil nutrient stoichiometry with shrub encroachment (SE) remain poorly understood, especially in subalpine areas. We examined the changes in soil nutrient concentration, nutrient stoichiometry, and organic carbon (OC) storage (at a depth of 0–5, 5–10 and 10–20 cm) in three successional shrub encroachment stages (early, mid and late) in an abandoned subalpine Eulalia pallens (Hackel) Kuntze grassland. An ANOVA showed that SE did not produce serious soil acidification, but significantly increased the soil OC and total phosphorous (TP) concentration, and improved the stoichiometry ratio of soil OC to total nitrogen (OC:TN) in all layers. OC storage tended to increase with SE. SE thus did not indicate degradation of the grassland. A redundancy analysis (RDA) and partial RDA revealed that the shrub relative cover and soil water content were the most important factors affecting the soil nutrient concentration, that the soil available phosphorous (AP), nitrogen, potassium, calcium (ACa), and magnesium concentration and shrub relative cover were the most important factors influencing soil nutrient stoichiometry ratios, and that soil OC:TN, TN:TP, OC:TN:TP, and AP:ACa ratios, bulk density, and pH were the most important factors influencing soil OC storage over SE. Our study provides insights into SE in grassland areas, and potentially provides a useful reference for ongoing grassland conservation and restoration in subalpine regions.

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28

Marinenko, Ryna B., Sonya Roberson, John S. Small, Barbara B. Thorne, Douglas Blackburn, Dale Kauffman, and Stefan Leigh. "Preparation and Certification of K-411 Glass Microspheres." Microscopy and Microanalysis 6, no. 6 (November 2000): 542–50. http://dx.doi.org/10.1007/s100050010059.

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AbstractThe production and characterization of NBS K-411 glass microspheres in the 2–40 μm range for certification as NIST Standard Reference Material® 2066 (SRM®) are described. Quantitative analysis and heterogeneity testing of the microspheres were done with an electron probe microanalyzer-X-ray energy dispersive spectrometry (EPMA-EDS) automated particle analysis procedure. Results for the trimmed and normalized data produced mean compositions for the elements Mg, Si, Ca, Fe, and O (calculated from stoichiometry) that are in good agreement with the certified values for the K-411 bulk glass (NBS SRM 470 Glasses for Mineral Analysis), but with uncertainties about twice as large as those for the bulk material. Differences from the bulk are attributable to microsphere geometry as well as mass and size effects.

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29

HEINZ, K., R. DÖLL, and M. KOTTCKE. "TENSOR LEED FOR THE GEOMETRICAL AND CHEMICAL STRUCTURE OF ALLOY SURFACES." Surface Review and Letters 03, no. 05n06 (October 1996): 1651–61. http://dx.doi.org/10.1142/s0218625x96002618.

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Low energy electron diffraction is still the most frequently used technique to retrieve the structure of surfaces. Multiple scattering of electrons on the one hand provides high structural precision but on the other hand also complicates the structural analysis and limits the complexity of accessible structures. This particularly applies to alloy surfaces with their enlarged variety of possible structures which comes by the increased size of the surface unit cell (chemically ordered alloys) or the unknown layer-dependent stoichiometry (disordered alloys). A way out of that dilemma comes by application and further development of the perturbation method Tensor LEED. We show that it can be extended to treat efficiently and accurately the chemical substitution of atoms. This allows easy access to the layer-dependent stoichiometry of chemically disordered alloys. Also, by periodic substitution of atoms, intensities calculated for an elemental crystal can be perturbed to yield the intensities for an ordered alloy. Moreover, we propose and test the application of a direct method which gives the deviations from bulk stoichiometry directly, i.e. without the usual trial and error procedure.

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30

Dehkordi, Arash Mehdizadeh, Sriparna Bhattacharya, Taghi Darroudi, Mehmet Karakaya, Courtney Kucera, John Ballato, Rasheed Adebisi, et al. "Optimizing thermal conduction in bulk polycrystalline SrTiO3−δ ceramics via oxygen non-stoichiometry – ERRATUM." MRS Communications 8, no. 04 (December 2018): 1484. http://dx.doi.org/10.1557/mrc.2018.227.

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31

Luther, Joseph M., and Jeffrey M. Pietryga. "Stoichiometry Control in Quantum Dots: A Viable Analog to Impurity Doping of Bulk Materials." ACS Nano 7, no. 3 (March 26, 2013): 1845–49. http://dx.doi.org/10.1021/nn401100n.

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32

Costa, G. A., M. M. Carnasciali, and E. Kaiser. "Evidence for Oxygen and Mercury Non-Stoichiometry in Hg-1201 HTC Superconductor." International Journal of Modern Physics B 13, no. 09n10 (April 20, 1999): 1023–28. http://dx.doi.org/10.1142/s0217979299000898.

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A review of the structural existing data on Hg-1201 shows evidence of non stoichiometry of the sample. In this compound not only oxygen but also Hg seems to be released or, perhaps, substituted. So, the production of bulk samples with optimal oxygen doping and homogeneus Hg content could be profitable for the study of the effect of the Hg solubility, allowing to confirm its existence till to room temperatures, and to test the effect of Hg impoverishment on other critical superconducting parameter different from Tc.

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33

Drehman, A. J., M. W. Dumais, J. A. Horrigan, G.-C. Wang, and Y.-F. Liew. "Near-surface stoichiometry of high temperature superconducting YBaCuO thin films." Journal of Materials Research 5, no. 7 (July 1990): 1392–96. http://dx.doi.org/10.1557/jmr.1990.1392.

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The surface morphology and near-surface chemical composition of high temperature superconducting Y–Ba–Cu–O thin films have been studied by Scanning Electron Microscopy (SEM) and Auger Electron Spectroscopy (AES) depth profiling. These films were fabricated on SrTiO3 substrates by RF diode sputter deposition and subsequent furnace annealing in oxygen. The chemical composition at and near the surface of thin films was found to differ from the bulk composition. At about 500 Å below the surface the Y, Ba, and Cu stoichiometry, as determined by AES, gradually approach that of the film interior. These results suggest that, for furnace annealed films, there may exist a minimum deposited Y–Ba–Cu–O film thickness in which superconductivity is possible. It was also found that the calculated copper concentration determined by AES during depth profiling is significantly lower than its actual value.

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34

Binhayeeniyi, N., A. Dasaesamoh, J. Khakong, P. Khaenamkaew, and S. Muensit. "Micro- and Macroscopic Observations of the Microtexture, the Dielectric and Piezoelectric Properties in Bulk and Multilayer Pb (Zr, Ti)O₃." Advanced Materials Research 55-57 (August 2008): 45–48. http://dx.doi.org/10.4028/www.scientific.net/amr.55-57.45.

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The objective of the present paper is to give an insight of the fundamental properties strongly depended on the crystallizing phase, grain size, thickness, including stoichiometry of material. The subject of this work is the lead zirconate titanate [Pb(Zr,Ti)O3, PZT] with its composition located at the morphotropic phase boundary (MPB) that were prepared by a solid state method [1] and a conventional sol-gel technique [2,3]. The samples prepared by the first methods are in a bulk form while the latter the multilayer. The physical property and the dielectric and piezoelectric properties of the PZT samples have been discussed comparatively when the sample size decreasing from the bulk to the thin-film scale.

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35

Yan, S. C., G. Yan, Ya Feng Lu, Y. Feng, and Lian Zhou. "Influence of Mg and B Stoichiometry on the Formation Behavior of MgB₂ Phase." Materials Science Forum 546-549 (May 2007): 2035–39. http://dx.doi.org/10.4028/www.scientific.net/msf.546-549.2035.

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Bulk samples with the stoichiometry of Mg:B=1:2 and 1:4 were prepared by solid state reaction method. The microstructure and constituent of the samples were investigated by using the scanning electron microscope (SEM) and the x-ray diffraction (XRD). XRD results showed that the MgB2 phase was first formed in all the samples with different stoichiometry of Mg and B, which indicated that the MgB2 was the most thermodynamically stable phase in the Mg-B binary system. For the samples of Mg:B=1:2, the MgB2 single phase was formed very well when these samples were sintered at 650°C~700°C. For the samples with later added Mg reaching to the stoichiometry of Mg:B=1:2, a longer reaction time or higher reaction temperature was required for the formation of the MgB2 single phase. The SEM results showed that the samples with later added Mg had dense microstructures, suggesting that the later addition of Mg could reduce the porosity of the sample. A small increase of the superconducting transition temperature, Tc, in the Mg addition sample resulted from the dense microstructures.

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36

Devyatkin, Sergei V. "Electrochemical Synthesis of Binary and Ternary Refractory Compounds in the System Ti-Si-B from Chloride-Fluoride Melts." Zeitschrift für Naturforschung A 62, no. 9 (September 1, 2007): 524–28. http://dx.doi.org/10.1515/zna-2007-0909.

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Electrochemical synthesis of binary and ternary compounds in the system Ti-Si-B from chloridefluoride melts has been investigated by voltammetry and electrolysis. Electrochemical syntheses of titanium diboride, four titanium silicides (TiSi2, TiSi, Ti5Si4, Ti5Si3), silicon tetraboride and a new ternary compound, Ti5Si3B3, have been found to be one-step processes. The stoichiometry of the deposited compounds has been found to correlate with the bulk concentration of Ti, Si and B ions in the melt.

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37

Brett, M. J., and R. R. Parsons. "Stoichiometry control mechanisms for bias-sputtered zinc-oxide thin films." Canadian Journal of Physics 63, no. 6 (June 1, 1985): 819–25. http://dx.doi.org/10.1139/p85-132.

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We have deposited transparent, conducting ZnO thin films of resistivity 3 × 10−3 Ω∙cm by the technique of DC planar-magnetron sputtering in a reactive Ar–O2 atmosphere, incorporating a reactive gas baffle and substrate RF discharge. The substrate discharge was found to increase the oxygen content of the growing film. Films at low values of the RF-induced substrate self-bias voltage were characterized by a brown colour, resistivities of about 4 × 10−2 Ω∙cm, and composition ZnO0.8. Films at higher bias voltages of −80 V were clear with resistivities of 3 × 10−3 Ω∙cm and a composition approaching stoichiometric ZnO. The oxidation of the films by the RF discharge was shown to occur through preferential resputtering and re-evaporation of excess zinc and by activation and ion-plating of oxygen species. Resputtering and re-evaporation rates were found to be enhanced above that expected for bulk Zn, owing to the loosely bound nature of surface adatoms during film growth.

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38

Domenichini, B., A. M. Flank, P. Lagarde, and S. Bourgeois. "Interfacial reaction between deposited molybdenum and TiO2(110) surface: role of the substrate bulk stoichiometry." Surface Science 560, no. 1-3 (July 2004): 63–78. http://dx.doi.org/10.1016/j.susc.2004.04.011.

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39

Viernstein, Alexander, Markus Kubicek, Maximilian Morgenbesser, Gregor Walch, Georg Christoph Brunauer, and Jürgen Fleig. "High‐Temperature Photochromism of Fe‐Doped SrTiO 3 Caused by UV‐Induced Bulk Stoichiometry Changes." Advanced Functional Materials 29, no. 23 (April 5, 2019): 1900196. http://dx.doi.org/10.1002/adfm.201900196.

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40

Paritskaya, Lyudmila N., Yuri S. Kaganovsky, and V. V. Bogdanov. "Intermetallic Growth: Structure-Sensitive Effects." Defect and Diffusion Forum 297-301 (April 2010): 567–72. http://dx.doi.org/10.4028/www.scientific.net/ddf.297-301.567.

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The kinetics of intermetallic growth in the bulk, along the surface and grain boundaries (GBs) was studied in the Cd-Ni, Cd-Cu and Cu-Sn systems. Bulk dynamic diffusion coefficients exceed by a few orders of magnitudes the tracer self-diffusion coefficients in homogeneous phases. The reasons for this difference are discussed in terms of departure of growing intermetallics from stoichiometry due to the simultaneous existence of two processes: interdiffusion through the growing phase layer and chemical reactions at interfaces. Accelerating contribution of GBs and free surfaces, as fast diffusion paths, into diffusion penetrability of growing intermetallics has been investigated. It was found that the rates of lateral phase spreading along free surfaces and GBs exceed several times the rate of phase growth in the bulk. Accelerating GB contribution depends on the grain size. Nano-dispersed thin films demonstrate maximal phase propagation rates, which several times exceed even the rates of lateral phase spreading along free surfaces in coarse-grained polycrystals.

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41

Al-Haji, Munira M. J., and Raad M. S. Al-Haddad. "Compositional, Structural and Morphological Analyses of Bulk GeS Alloy and its Thin Films." Materials Science Forum 1039 (July 20, 2021): 398–405. http://dx.doi.org/10.4028/www.scientific.net/msf.1039.398.

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Bulk Germanium monosulphide (GeS) alloy was synthesized using the usual melt-quenching technique. Its grains were used as the source material to deposit thin films by vacuum thermal evaporation. Thin-films samples were doped with 1, 2, and 3 at.% indium by thermal co-evaporation and annealed in a vacuum at temperatures 373, 473 and 550 K for an hour. Compositional, structural, and morphological properties of the bulk GeS alloy and its thin films were investigated by Energy Dispersive X-Ray Spectroscopy (EDS), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) techniques. The analyses verified the stoichiometry (GeS) of the starting material in the prepared thin films. They also revealed that the thin films under study are amorphous, homogeneous, without any cracks deposited uniformly on the glass substrate with thickness 650 to 700 nm.

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42

Goodson, K. E., M. I. Flik, L. T. Su, and D. A. Antoniadis. "Prediction and Measurement of the Thermal Conductivity of Amorphous Dielectric Layers." Journal of Heat Transfer 116, no. 2 (May 1, 1994): 317–24. http://dx.doi.org/10.1115/1.2911402.

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Thermal conduction in amorphous dielectric layers affects the performance and reliability of electronic circuits. This work analyzes the influence of boundary scattering on the effective thermal conductivity for conduction normal to amorphous silicon dioxide layers, kn,eff. At 10 K, the predictions agree well with previously reported data for deposited layers, which show a strong reduction of kn,eff compared to the bulk conductivity, kbulk. A steady-state technique measures kn,eff near room temperature of silicon dioxide layers fabricated using oxygen-ion implantation (SIMOX). The predictions and the SIMOX data, which agree closely with kbulk, show that boundary scattering is not important at room temperature. Lower than bulk conductivities of silicon dioxide layers measured elsewhere near room temperature must be caused by interfacial layers or differences in microstructure or stoichiometry.

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43

Griffin, W. L., and S. Y. O'Reilly. "Mantle-derived sapphirine." Mineralogical Magazine 50, no. 358 (December 1986): 635–40. http://dx.doi.org/10.1180/minmag.1986.050.358.08.

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AbstractA xenolith from the Delegate breccia pipe (New South Wales, Australia) contains sapphirine in equilibrium with aluminous clinopyroxene, garnet, and plagioclase (An48). This unusual assemblage probably developed from a clinopyroxene (±spinel ± plagioclase) cumulate during cooling from > 1400°C to c. 1000°C at pressures near 15 kbar. The sapphirine is close to the 7:9:3 composition, suggesting that bulk composition is more important than P-T conditions in determining the stoichiometry of natural sapphirines. A similar occurrence of sapphirine has also been recorded in mantlederived xenoliths from the Stockdale kimberlite in Kansas. Re-examination of sapphirine granulites from Finero suggests that their primary assemblages and origin may have been similar to those of the Delegate xenolith. Sapphirine is clearly stable under upper-mantle conditions in Ca-Al-Mg-rich bulk compositions.

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44

Schwarz, Holger, Thomas Uhlig, Niels Rösch, Thomas Lindner, Fabian Ganss, Olav Hellwig, Thomas Lampke, Guntram Wagner, and Thomas Seyller. "CoCrFeNi High-Entropy Alloy Thin Films Synthesised by Magnetron Sputter Deposition from Spark Plasma Sintered Targets." Coatings 11, no. 4 (April 17, 2021): 468. http://dx.doi.org/10.3390/coatings11040468.

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Two magnetron sputter targets of CoCrFeNi High-Entropy Alloy (HEA), both in equal atomic ratio, were prepared by spark plasma sintering. One of the targets was fabricated from a homogeneous HEA powder produced via gas atomisation; for the second target, a mixture of pure element powders was used. Economic benefits can be achieved by mixing pure powders in the intended ratio in comparison to the gas atomisation of the specific alloy composition. In this work, thin films deposited via magnetron sputtering from both targets are analysed. The surface elemental composition is investigated by X-ray photoelectron spectroscopy, whereas the bulk stoichiometry is measured by X-ray fluorescence spectroscopy. Phase information and surface microstructure are investigated using X-ray diffraction and scanning electron microscopy, respectively. It is demonstrated that the stoichiometry, phase composition and microscopic structure of the as-deposited HEA thin films are almost identical if the same deposition parameters are used.

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45

Marvel, C. J., K. D. Behler, J. C. LaSalvia, V. Domnich, R. A. Haber, M. Watanabe, and M. P. Harmer. "Extending ζ-factor microanalysis to boron-rich ceramics: Quantification of bulk stoichiometry and grain boundary composition." Ultramicroscopy 202 (July 2019): 163–72. http://dx.doi.org/10.1016/j.ultramic.2019.04.008.

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46

Tüzemen, S., and M. R. Brozel. "Effect of non-stoichiometry on near-band-edge absorption and non- radiative recombination in bulk GaAs." Materials Science and Engineering: B 14, no. 1 (June 1992): 47–52. http://dx.doi.org/10.1016/0921-5107(92)90327-6.

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47

Plechaty, M. "Determination of metal stoichiometry in LaSrCu-oxide, YBaCu-oxide, BiCaSrCu-oxide superconducting films and bulk samples." Talanta 36, no. 5 (May 1989): 609–11. http://dx.doi.org/10.1016/0039-9140(89)80133-x.

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48

Magro, Fernando, Monica Ceretti, Martin Meven, and Werner Paulus. "Infrared furnace for in situ neutron single-crystal diffraction studies in controlled gas atmospheres at high temperatures." Journal of Applied Crystallography 54, no. 3 (May 25, 2021): 822–29. http://dx.doi.org/10.1107/s1600576721003198.

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To understand oxygen diffusion mechanisms in non-stoichiometric oxides, the possibility to explore structural changes as a function of the oxygen partial pressure with temperature and related oxygen bulk stoichiometry is mandatory. This article reports on the realization of a high-temperature furnace, suitable for single-crystal neutron diffraction, working continuously at temperatures of up to 1000°C at different and adjustable partial gas pressures of up to 2 bar (1 bar = 100 kPa). This allows exploration of the phase diagrams of non-stoichiometric oxides under in situ conditions and controlled oxygen partial pressure. As a pilot study, the structural changes of Pr2NiO4+δ were explored at room temperature (δ ≃ 0.24) and at 900°C under 1 bar P(O2) (δ ≃ 0.13) as well as under secondary vacuum (approximately 10−5 mbar) conditions yielding a δ close to zero. The strong anharmonic displacements of the apical oxygen atoms along the [110] shallow diffusion pathway, which were previously observed at room temperature and 400°C, become more isotropic at 900°C. The study shows that the anisotropic oxygen displacements, here related to lattice instabilities, play a major role in understanding oxygen diffusion pathways and related activation energies at moderate temperatures. This also shows the importance of the availability of reaction cells for single-crystal neutron diffraction to explore the phase diagram and associated structural changes of non-stoichiometric oxygen ion conductors and respective diffusion mechanisms.

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49

North, R. B., and W. M. Lau. "The preparation of stoichiometric mercury cadmium telluride surfaces." Canadian Journal of Physics 65, no. 8 (August 1, 1987): 1044–46. http://dx.doi.org/10.1139/p87-171.

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A technique involving cathodization of an anodized surface has been proposed as a surface treatment of mercury cadmium telluride substrates in the fabrication of infrared-sensitive devices. The resultant surface was analyzed with X-ray photoelectron spectroscopy and compared with surfaces produced by cleavage, sputtering, and chemical etching. It was found that the cathodized surface had a surface composition close to the bulk stoichiometry. The first monolayer of the surface was enriched in mercury and depleted in cadmium. This surface was also more inert towards air oxidation than the Br–methanol treated surface, probably because of the surface enrichment of mercury.

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50

Wong, Kaikee, P. E. Batson, and John Silcox. "EELS study of NiSi2Si(111) interface in STEM." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 858–59. http://dx.doi.org/10.1017/s0424820100150125.

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Experimental studies of the NiSi2/Si(111) interface are difficult since the interface is only 3 Å wide and separating the interfacial signals from bulk signals is hard. When equipped with an EELS detector, a STEM becomes a powerful tool in studying the electronic properties of an interface. By locating the electron probe at the interface, at bulk Si and at bulk silicide, the electronic properties of the NiSi2/Si(111) interface can be identified.An A-type NiSi2 template was grown using Tung's scheme. To increase the film thickness to 200 Å, 60 Å of Ni was deposited on the template and annealed at 550°C for 10 min. A cross-section TEM sample was prepared by dimpling and ion-milling. Within 70 Å of the interface, the specimen stoichiometry was found to be that of NiSi2 with TEM lattice imaging and x-ray EDS. Beyond that the concentration of Ni increased and approached that of NiSi. EELS measurements were carried out at the IBM VG HB501 STEM operating at 120 keV equipped with a CCD EELS detection system and a Wien filter.

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