Journal articles: 'High temperature crystal structurephase transition'

1

Khan, Humayun, and A. H. Khan. "High temperature phase transition in KH2PO4 crystal." Bulletin of Materials Science 16, no. 5 (October 1993): 357–63. http://dx.doi.org/10.1007/bf02759548.

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Połomska, M., J. Wolak, and L. Szcześniak. "High temperature phase transition of β-LiNH4SO4single crystal." Ferroelectrics 159, no. 1 (September 1994): 179–84. http://dx.doi.org/10.1080/00150199408007569.

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Yan, Feng, and Ye-Ning Wang. "Phase transition of C60 crystal in high temperature regime." Applied Physics Letters 73, no. 4 (July 27, 1998): 476–77. http://dx.doi.org/10.1063/1.121905.

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Bento, I. C. V., P. T. C. Freire, F. E. A. Melo, J. Mendes Filho, A. J. D. Moreno, M. R. Joya, and P. S. Pizani. "High temperature phase transition in monohydrated L-asparagine crystal." Solid State Communications 141, no. 1 (January 2007): 29–32. http://dx.doi.org/10.1016/j.ssc.2006.09.041.

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Chen, Xianhui, Pengcheng Dai, Donglai Feng, Tao Xiang, and Fu-Chun Zhang. "Iron-based high transition temperature superconductors." National Science Review 1, no. 3 (July 3, 2014): 371–95. http://dx.doi.org/10.1093/nsr/nwu007.

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Abstract In a superconductor electrons form pairs and electric transport becomes dissipation-less at low temperatures. Recently discovered iron-based superconductors have the highest superconducting transition temperature next to copper oxides. In this article, we review material aspects and physical properties of iron-based superconductors. We discuss the dependence of transition temperature on the crystal structure, the interplay between antiferromagnetism and superconductivity by examining neutron scattering experiments, and the electronic properties of these compounds obtained by angle-resolved photoemission spectroscopy in link with some results from scanning tunneling microscopy/spectroscopy measurements. Possible microscopic model for this class of compounds is discussed from a strong coupling point of view.

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Xia, Zhang, Wan Song-Ming, Yin Shao-Tang, and You Jing-Lin. "High-Temperature Raman Investigation on Phase Transition of LBO Crystal." Chinese Physics Letters 26, no. 11 (October 29, 2009): 113301. http://dx.doi.org/10.1088/0256-307x/26/11/113301.

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Scheel, H. J., and F. Licci. "Crystal Growth of High Temperature Superconductors." MRS Bulletin 13, no. 10 (October 1988): 56–61. http://dx.doi.org/10.1557/s0883769400064204.

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The discovery of high temperature superconductivity (HTSC) in oxide compounds has confronted materials scientists with many challenging problems. These include the preparation of ceramic samples with critical current density of about 106 A/cm2 at 77 K and sufficient mechanical strength for large-scale electrotechnical and magnetic applications and the preparation of epitaxial thin films of high structural perfection for electronic devices.The main interest in the growth of single crystals is for the study of physical phenomena, which will help achieve a theoretical understanding of HTSC. Theorists still do not agree on the fundamental mechanisms of HTSC, and there is a need for good data on relatively defect-free materials in order to test the many models. In addition, the study of the role of defects like twins, grain boundaries, and dislocations in single crystals is important for understanding such parameters as the critical current density. The study of HTSC with single crystals is also expected to be helpful for finding optimum materials for the various applications and hopefully achieving higher values of the superconducting transition temperature Tc than the current maximum of about 125 K. It seems unlikely at present that single crystals will be used in commercial devices, but this possibility cannot be ruled out as crystal size and quality improve.

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Masciocchi, Norberto, and William Parrish. "New Crystal Data for High Temperature Hexagonal Silver Sulfate." Powder Diffraction 5, no. 1 (March 1990): 50–52. http://dx.doi.org/10.1017/s0885715600015232.

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AbstractPowder data for Ag2SO4were obtained with a conventional diffractometer equipped with a vacuum heating chamber. The transition from the low-temperature orthorhombic phase occurs over a temperature range of about 415° to 425°C and forms a hexagonal phase plus metallic silver. The lack of a sharp transition must be taken into account in high-temperature X-ray diffraction or DSC/DTA studies. The lattice parameters of the high-temperature hexagonal phase are a = 5.531(3), c = 7.456(5)Å at 440°C, λ = 1.540562 Å. Crystal structure determination was not completed because of uncertainty in the chemical composition.

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Sist, Mattia, Jiawei Zhang, and Bo Brummerstedt Iversen. "Crystal structure and phase transition of thermoelectric SnSe." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 72, no. 3 (May 13, 2016): 310–16. http://dx.doi.org/10.1107/s2052520616003334.

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Tin selenide-based functional materials are extensively studied in the field of optoelectronic, photovoltaic and thermoelectric devices. Specifically, SnSe has been reported to have an ultrahigh thermoelectric figure of merit of 2.6 ± 0.3 in the high-temperature phase. Here we report the evolution of lattice constants, fractional coordinates, site occupancy factors and atomic displacement factors with temperature by means of high-resolution synchrotron powder X-ray diffraction measured from 100 to 855 K. The structure is shown to be cation defective with a Sn content of 0.982 (4). The anisotropy of the thermal parameters of Sn becomes more pronounced approaching the high-temperature phase transition (∼ 810 K). Anharmonic Gram–Charlier parameters have been refined, but data from single-crystal diffraction appear to be needed to firmly quantify anharmonic features. Based on modelling of the atomic displacement parameters the Debye temperature is found to be 175 (4) K. Conflicting reports concerning the different coordinate system settings in the low-temperature and high-temperature phases are discussed. It is also shown that the high-temperatureCmcmphase is not pseudo-tetragonal as commonly assumed.

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Igartua, J. M., M. I. Aroyo, E. Kroumova, and J. M. Perez-Mato. "Search for Pnma materials with high-temperature structural phase transitions." Acta Crystallographica Section B Structural Science 55, no. 2 (April 1, 1999): 177–85. http://dx.doi.org/10.1107/s0108768198013342.

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A systematic search for structures having a high-temperature structural phase transition can be carried out through the identification in the structural databases of those structures that can be considered pseudosymmetric. Pseudosymmetry in a crystal structure indicates the possibility of a similar configuration of higher symmetry. If the distortion relating both structures is small enough, it can be expected that the crystal acquires the more symmetric configuration through a Landau-type phase transition at a higher temperature. Here, we present the results of such a search among inorganic structures with space group Pnma retrieved from the Inorganic Crystal Structure Database. Pseudosymmetry has indeed been detected in those compounds with a known (displacive) Landau-type phase transition at higher temperatures. This is measured by a parameter Δ, which measures the maximal atomic displacement relating the pseudosymmetry-transformed structure and the original one. In most of these compounds with a known phase transition, this parameter was smaller than 1.0 Å for at least one minimal supergroup of Pnma. The database contains 144 additional structures with pseudosymmetry features under the same quantitative limit. A comparison of the Δ distributions in both sets of compounds suggests a smaller Δ window (with 0.7 Å as maximal value) for selecting the materials having maximal probability of exhibiting a phase transition at higher temperatures. A set of 58 compounds fulfils this criterion.

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Xu, Y., S. Carlson, A. Sjödin, and R. Norrestam. "Phase Transition in Cs2KMnF6: Crystal Structures of Low- and High-Temperature Modifications." Journal of Solid State Chemistry 150, no. 2 (March 2000): 399–403. http://dx.doi.org/10.1006/jssc.1999.8613.

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van de Streek, Jacco, Edith Alig, Simon Parsons, and Liana Vella-Zarb. "A jumping crystal predicted with molecular dynamics and analysed with TLS refinement against powder diffraction data." IUCrJ 6, no. 1 (January 1, 2019): 136–44. http://dx.doi.org/10.1107/s205225251801686x.

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By running a temperature series of molecular dynamics (MD) simulations starting from the known low-temperature phase, the experimentally observed phase transition in a `jumping crystal' was captured, thereby providing a prediction of the unknown crystal structure of the high-temperature phase and clarifying the phase-transition mechanism. The phase transition is accompanied by a discontinuity in two of the unit-cell parameters. The structure of the high-temperature phase is very similar to that of the low-temperature phase. The anisotropic displacement parameters calculated from the MD simulations readily identified libration as the driving force behind the phase transition. Both the predicted crystal structure and the phase-transition mechanism were verified experimentally using TLS (translation, libration, screw) refinement against X-ray powder diffraction data.

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Enjalbert, Renée, and Jean Galy. "CH3CN: X-ray structural investigation of a unique single crystal. β → α phase transition and crystal structure." Acta Crystallographica Section B Structural Science 58, no. 6 (November 28, 2002): 1005–10. http://dx.doi.org/10.1107/s0108768102017603.

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The phase transition from the low- (β) to the high-temperature (α) form of acetonitrile, CH3CN, has been directly observed and studied on a unique single crystal. Both the β and α structures have been determined at temperatures close to the transition temperature (206 K and 201 K), taking advantage of the hysteresis. A single crystal of the β form was obtained for the first time.

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Yamada, Takahiro, Takuji Ikeda, Ralf P. Stoffel, Volker L. Deringer, Richard Dronskowski, and Hisanori Yamane. "Synthesis, Crystal Structure, and High-Temperature Phase Transition of the Novel Plumbide Na2MgPb." Inorganic Chemistry 53, no. 10 (May 2, 2014): 5253–59. http://dx.doi.org/10.1021/ic500466w.

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15

Lu, Mengya, Di Zhou, Fangfei Li, Yongfu Liang, Qiang Zhou, Xiaoli Huang, and Tian Cui. "Disorder–order structural transition of single crystal hydrogen chloride under high pressure–temperature." Physical Chemistry Chemical Physics 21, no. 32 (2019): 17655–61. http://dx.doi.org/10.1039/c9cp02839k.

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Lapina, O. B., V. V. Terskikh, A. A. Shubin, V. M. Mastikhin, K. M. Eriksen, and R. Fehrmann. "High-Temperature NMR Studies of the Glass−Crystal Transition in the Cs2S2O7−V2O5System." Journal of Physical Chemistry B 101, no. 45 (November 1997): 9188–94. http://dx.doi.org/10.1021/jp971789b.

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17

Skakunova, Kseniya D., and Denis A. Rychkov. "Low Temperature and High-Pressure Study of Bending L-Leucinium Hydrogen Maleate Crystals." Crystals 11, no. 12 (December 16, 2021): 1575. http://dx.doi.org/10.3390/cryst11121575.

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The polymorphism of molecular crystals is a well-known phenomenon, resulting in modifications of physicochemical properties of solid phases. Low temperatures and high pressures are widely used to find phase transitions and quench new solid forms. In this study, L-Leucinium hydrogen maleate (LLHM), the first molecular crystal that preserves its anomalous plasticity at cryogenic temperatures, is studied at extreme conditions using Raman spectroscopy and optical microscopy. LLHM was cooled down to 11 K without any phase transition, while high pressure impact leads to perceptible changes in crystal structure in the interval of 0.0–1.35 GPa using pentane-isopentane media. Surprisingly, pressure transmitting media (PTM) play a significant role in the behavior of the LLHM system at extreme conditions—we did not find any phase change up to 3.05 GPa using paraffin as PTM. A phase transition of LLHM to amorphous form or solid–solid phase transition(s) that results in crystal fracture is reported at high pressures. LLHM stability at low temperatures suggests an alluring idea to prove LLHM preserves plasticity below 77 K.

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Gui, Xin, Gregory J. Finkelstein, David E. Graf, Kaya Wei, Dongzhou Zhang, Ryan E. Baumbach, Przemyslaw Dera, and Weiwei Xie. "Enhanced Néel temperature in EuSnP under pressure." Dalton Transactions 48, no. 16 (2019): 5327–34. http://dx.doi.org/10.1039/c9dt00449a.

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The high-pressure single crystal X-ray diffraction results for EuSnP are reported with no structural phase transition below ∼6.2 GPa. Temperature-dependent resistivity measurements up to 2.15 GPa indicate that the antiferromagnetic transition temperature (T_N) is significantly enhanced under pressure.

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19

Ibberson, Richard M. "The low-temperature phase III structure and phase transition behaviour of cyclohexanone." Acta Crystallographica Section B Structural Science 62, no. 4 (July 12, 2006): 592–98. http://dx.doi.org/10.1107/s0108768106015485.

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The crystal structure of phase III of perdeuterocyclohexanone, C6D10O, has been determined at 5 K using high-resolution neutron powder diffraction. Below its melting point of 245 K cyclohexanone forms a plastic crystal in the space group Fm\bar 3m. On cooling below 225 K the crystal transforms to the monoclinic phase III structure in the space group P21/n. The orthorhombic phase II structure exists under high pressure, but the triple point for all three phases is close to atmospheric pressure. Details of the phase II structure are also reported at 4.8 kbar (273 K) and ambient pressure. The phase behaviour of the compound and isotope effects are discussed.

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Bennett, J. C., F. W. Boswell, S. Ritchie, J. M. Corbett, and A. Prodan. "Observation of a high-temperature incommensurate phase transition and discommensurations in TaTe4." Proceedings, annual meeting, Electron Microscopy Society of America 49 (August 1991): 566–67. http://dx.doi.org/10.1017/s0424820100087148.

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In many ways, TaTe4 and NbTe4 are nearly prototypical compounds for the study of charge-density waves (CDW). The compounds have a quasi-one-dimensional crystal structure in which chains of metal atoms are centered within extended cages of Te atoms in square antiprismatic coordination. The observed lattice distortions, involving mainly longitudinal motions of the metal atoms along the chains, correspond to that of the classic CDW model. In addition, the compounds exhibit the full spectrum of possible CDW-driven phase transitions: commensurate-to-incommensurate (C to IC), C to C and IC to IC. The subcell of TaTe4 is tetragonal with axes (a x a x c). At room temperature, the crystal is commensurately modulated giving rise to a supercell with axes (2a x 2a x 3c) and, upon heating, has been observed to undergo a C to C transition at about 450 K. In this paper, we report an additional C to IC transition occurring above 550 K. The evolution of the microstructure upon heating, including the formation of discommensuration arrays in the IC state, has been revealed by satellite dark-field (SDF) imaging.

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Ziegler, Raimund, Martina Tribus, Clivia Hejny, and Gunter Heymann. "Single-Crystal Structure of HP-Sc2TeO6 Prepared by High-Pressure/High-Temperature Synthesis." Crystals 11, no. 12 (December 13, 2021): 1554. http://dx.doi.org/10.3390/cryst11121554.

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The first high-pressure scandium tellurate HP-Sc2TeO6 was synthesized from an NP-Sc2TeO6 normal-pressure precursor at 12 GPa and 1173 K using a multianvil apparatus (1000 t press, Walker-type module). The compound crystallizes in the monoclinic space group P2/c (no. 13) with a = 729.43(3), b = 512.52(2), c = 1095.02(4) pm and β = 103.88(1)°. The structure was refined from X-ray single-crystal diffractometer data: R1 = 0.0261, wR2 = 0.0344, 568 F2 values and 84 variables. HP-Sc2TeO6 is isostructural to Yb2WO6 and is built up from TeO6 octahedra, typical for tellurate(VI) compounds. During synthesis, a reconstructive transition from P321 (normal-pressure modification) to P2/c (high-pressure modification) takes place and the scandium–oxygen distances as well as the coordination number of scandium increase. However, the coordination sphere around the Te6+ cations gets only slightly distorted. High-temperature powder XRD investigations revealed a back-transformation of HP-Sc2TeO6 to the ambient-pressure modification above 973 K.

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Yoshiasa, Akira, Tomotaka Nakatani, Akihiko Nakatsuka, Maki Okube, Kazumasa Sugiyama, and Tsutomu Mashimo. "High-temperature single-crystal X-ray diffraction study of tetragonal and cubic perovskite-type PbTiO3phases." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 72, no. 3 (May 26, 2016): 381–88. http://dx.doi.org/10.1107/s2052520616005114.

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A high-temperature single-crystal X-ray diffraction study of a synthetic PbTiO3perovskite was carried out over the wide temperature range 298–928 K. A transition from a tetragonal (P4mm) to a cubic (Pm \bar 3 m) phase has been revealed near 753 K. In the non-centrosymmetricP4mmsymmetry group, the difference in relative displacement between Pb and O along thec-axis is much larger than that between Ti and O. The Pb and Ti cations contribute sufficiently to polarization being shifted in the opposite direction compared with the shift of O atoms. Deviation from the linear changes in Debye–Waller factors and bonding distances in the tetragonal phases can be interpreted as a precursor phenomenon before the phase transition. Disturbance of the temperature factorUeqfor O is observed in the vicinity of the transition point, whileUeqvalues for Pb and Ti are continuously changing with increasing temperature. The O site includes the clear configurational disorder in the cubic phase. The polar local positional distortions remain in the cubic phase and are regarded as the cause of the paraelectricity. Estimated values of the Debye temperature ΘDfor Pb and Ti are 154 and 467 K in the tetragonal phase and decrease 22% in the high-temperature phase. Effective potentials for Pb and Ti change significantly and become soft after the phase transition.

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Heymann, Gunter, and Elisabeth Selb. "Li2Pt3Se4: a new lithium platinum selenide with jaguéite-type crystal structure by multianvil high-pressure/high-temperature synthesis." Zeitschrift für Naturforschung B 71, no. 11 (November 1, 2016): 1095–104. http://dx.doi.org/10.1515/znb-2016-0165.

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AbstractThe monoclinic lithium platinum selenide Li2Pt3Se4 was obtained via a multianvil high-pressure/high-temperature route at 8 GPa and 1200°C starting from a stoichiometric mixture of lithium nitride, selenium, and platinum. The structure of the ternary alkali metal-transition metal-selenide was refined from single-crystal X-ray diffractometer data: P21/c (no. 14), a=525.9(2), b=1040.6(2), c=636.5(2) pm, β=111.91(1)°, R1=0.0269, wR2=0.0569 (all data) for Li2Pt3Se4. Furthermore, the isostructural mineral phases jaguéite (Cu2Pd3Se4) and chrisstanleyite (Ag2Pd3Se4) were reinvestigated in their ideal stoichiometric ratio. The syntheses of the mineral phases were also carried out under multianvil conditions. Single-crystal data revealed a hitherto not described structural disorder of the transition metal atoms.

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Fitzgerald, S. P., and S. L. Dudarev. "Dislocation pile-ups in Fe at high temperature." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 464, no. 2098 (May 13, 2008): 2549–59. http://dx.doi.org/10.1098/rspa.2008.0116.

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Dislocation ‘pile-ups’ occur in crystals when a number of similar dislocations, gliding in a common slip plane, are driven by an applied stress towards an obstacle that they cannot overcome. In contrast to dislocation walls, pile-ups give rise to a long-range stress field, and their properties strongly influence the plastic behaviour of the crystal as a whole. In this paper, we apply the analytic model of a pile-up (due to Eshelby, Frank and Nabarro) to a cubic crystal. Full anisotropic elasticity is used, and the model is extended to predict the plastic displacement generated by a dislocation source during the formation of a pile-up. The results are applied to Fe close to the temperature of the α–γ phase transition, where the inclusion of anisotropy leads to a strikingly different prediction from that of the isotropic approximation.

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NUÑEZ REGUEIRO, MANUEL D., and DARÍO CASTELLO. "THERMAL CONDUCTIVITY OF HIGH TEMPERATURE SUPERCONDUCTORS." International Journal of Modern Physics B 05, no. 12 (July 20, 1991): 2003–35. http://dx.doi.org/10.1142/s021797929100078x.

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We review and analyze the data on the thermal conductivity of both ceramic and single crystal samples of high temperature superconductors. A universal pattern can be extracted and interpreted in the following way: phonons are the main heat carriers in these materials, and in the high temperature range the thermal conductivity κ is almost constant due to phonon scattering against disorder; below the superconducting transition temperature κ increases as phonon scattering against carriers condensing into the superconducting state decreases and at still lower temperatures there is a region in which a T2 law is obeyed that most probably is due to resonant phonon scattering against low energy excitations, i.e. tunneling systems similar to those found in disordered materials. The origin of the relevant disorder is discussed.

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26

Williams, Jack M., Mark A. Beno, K. Douglas Carlson, Urs Geiser, H. C. Ivy Kao, Aravinda M. Kini, Leigh C. Porter, Arthur J. Schultz, and Robert J. Thorn. "High transition temperature inorganic oxide superconductors: synthesis, crystal structure, electrical properties, and electronic structure." Accounts of Chemical Research 21, no. 1 (January 1988): 1–7. http://dx.doi.org/10.1021/ar00145a001.

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27

Zhang, Lisong, Mingxia Xu, Baoan Liu, Lili Zhu, Bo Wang, Hailiang Zhou, Fafu Liu, and Xun Sun. "New annealing method to improve KD2PO4 crystal quality: learning from high temperature phase transition." CrystEngComm 17, no. 25 (2015): 4705–11. http://dx.doi.org/10.1039/c5ce00813a.

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28

de Leeuw, D. M., W. A. Groen, L. F. Feiner, and E. E. Havinga. "Correlation between the superconducting transition temperature and crystal structure of high-Tc cuprate compounds." Physica C: Superconductivity 166, no. 1-2 (March 1990): 133–39. http://dx.doi.org/10.1016/0921-4534(90)90564-u.

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Antao, Sytle M., and Ishmael Hassan. "BaCO3: high-temperature crystal structures and the Pmcn→R3m phase transition at 811°C." Physics and Chemistry of Minerals 34, no. 8 (June 30, 2007): 573–80. http://dx.doi.org/10.1007/s00269-007-0172-8.

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30

Sun, Shijing, Zeyu Deng, Yue Wu, Fengxia Wei, Furkan Halis Isikgor, Federico Brivio, Michael W. Gaultois, et al. "Variable temperature and high-pressure crystal chemistry of perovskite formamidinium lead iodide: a single crystal X-ray diffraction and computational study." Chemical Communications 53, no. 54 (2017): 7537–40. http://dx.doi.org/10.1039/c7cc00995j.

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Wójcik, Grażyna, and Jolanta Holband. "Variable-temperature crystal structure studies of m-nitroaniline." Acta Crystallographica Section B Structural Science 57, no. 3 (May 25, 2001): 346–52. http://dx.doi.org/10.1107/s010876810100489x.

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The crystal structure of m-nitroaniline has been examined at several temperatures over the 90–350 K range. Thermal evolution of the lattice parameters reveals a weak anomaly at 110 K and an important one at 300 K. The thermal expansion coefficients have been calculated at several temperatures and the principal axes cross-sections of the tensor were drawn. The lattice contraction along the b axis direction has been observed. The rigid-body analysis including an attached rigid group has provided the values of the translation and libration tensors at temperatures studied. The results indicate that m-nitroaniline undergoes a glass transition around 130 K arising from freezing molecular librations and translations. From above 340 K the growing plasticity of the m-nitroaniline crystal results in the loss of X-ray diffraction reflections. This is probably a second-order phase transition. It is coupled with a considerable increase in the nitro group torsion amplitude, but the NH...O hydrogen bonds are preserved. Analysis of the temperature evolution of short intermolecular distances enabled us to consider the occurrence of reorienting aggregates of hydrogen-bonded molecules in the high-temperature plastic phase.

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Dubskikh, Vadim A., Anna A. Lysova, Denis G. Samsonenko, Danil N. Dybtsev, and Vladimir P. Fedin. "Topological polymorphism and temperature-driven topotactic transitions of metal–organic coordination polymers." CrystEngComm 22, no. 38 (2020): 6295–301. http://dx.doi.org/10.1039/d0ce01045f.

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A facile crystal-to-crystal solid-state phase transition between a low-temperature phase and a high temperature phase changes the MOF topology and involves a significant rearrangement of bulky organic ligands.

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Haines, Charles R. S., Giulio I. Lampronti, Wim T. Klooster, Simon J. Coles, Sian E. Dutton, and Michael A. Carpenter. "Morin-type transition in 5C pyrrhotite." American Mineralogist 105, no. 9 (September 1, 2020): 1404–11. http://dx.doi.org/10.2138/am-2020-7266.

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Abstract We report the discovery of a low-temperature spin-flop transition in 5C pyrrhotite at ~155 K that is similar to those seen in hematite at 260 K and FeS (troilite) at 440 K. The 5C crystal was produced by annealing a 4C pyrrhotite crystal at 875 K to produce a change in the vacancy-ordering scheme that developed during cooling. The 5C structure is confirmed by single-crystal X-ray diffraction and the stoichiometry and homogeneity by electron microprobe and SEM BSE mapping. Resonant ultrasound spectroscopy (RUS), heat capacity, and magnetization measurements from room temperature down to 2 K are reported. The transition is marked by a steep change in elastic properties at the transition temperature, a peak in the heat capacity, and weak anomalies in measurements of magnetization. Magnetic hysteresis loops and comparison with the magnetic properties of 4C pyrrhotite suggest that the transition involves a change in orientation of moments between two different antiferromagnetic structures, perpendicular to the crystallographic c-axis at high temperatures and parallel to the crystal-lographic c-axis at low temperatures. The proposed structures are consistent with a group theoretical treatment that also predicts a first-order transition between the magnetic structures.

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Bruno, Giovanni, and Sven C. Vogel. "Simultaneous determination of high-temperature crystal structure and texture of synthetic porous cordierite." Journal of Applied Crystallography 50, no. 3 (April 13, 2017): 749–62. http://dx.doi.org/10.1107/s160057671700406x.

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The evolution of the crystal structure and crystallographic texture of porous synthetic cordierite was studied byin situhigh-temperature neutron diffraction up to 1373 K, providing the firstin situhigh-temperature texture measurement of this technologically important material. It was observed that the crystal texture slightly weakens with increasing temperature, concurrently with subtle changes in the crystal structure. These changes are in agreement with previous work, leading the authors to the conclusion that high-temperature neutron diffraction allows reliable crystallographic characterization of materials with moderate texture. It was also observed that structural changes occur at about the glass transition temperature of the cordierite glass (between 973 and 1073 K). Crystal structure refinements were conducted with and without quantitative texture analysis being part of the Rietveld refinement, and a critical comparison of the results is presented, contributing to the sparse body of literature on combined texture and crystal structure refinements.

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Shlyaykher, Alena, Thomas Pippinger, Thomas Schleid, Olaf Reckeweg, and Frank Tambornino. "Syntheses, crystallographic characterization, and structural relations of Rb[SCN]." Zeitschrift für Kristallographie - Crystalline Materials 237, no. 1-3 (March 1, 2022): 69–75. http://dx.doi.org/10.1515/zkri-2022-0015.

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Abstract Colorless rubidium thiocyanate was synthesized by three different approaches. DCS-TGA measurements allowed for extraction of phase transition, melting, and decomposition temperatures. Single-crystal X-ray diffraction showed Rb[SCN] to crystallize in the low-temperature LT-K[SCN] crystal structure type (Pbcm, oP16). Above its phase-transition temperature (432.1 K) the title compound crystallizes with the high-temperature HT-K[SCN] crystal structure type (I4/mcm, tI28) with head-to-tail disordered thiocyanate anions. Both modifications are related to one another and to the LT/HT-Cs[SCN] structure types, and the relation has been studied in detail employing the Bärnighausen formalism. Phase purity and bulk phase transition were confirmed by temperature-dependent PXRD.

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Deppisch, C., G. Liu, A. Hall, Y. Xu, A. Zangvil, J. K. Shang, and J. Economy. "The crystallization and growth of AlB2 single crystal flakes in aluminum." Journal of Materials Research 13, no. 12 (December 1998): 3485–98. http://dx.doi.org/10.1557/jmr.1998.0476.

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An in situ high temperature heat treatment was used to investigate the crystallization and growth behavior of AlB2 flakes in aluminum. Aluminum samples containing 1.8% boron were heated above the liquidus and then rapidly cooled through the Al(L) + AlB12 region to avoid the formation of AlB12 crystals. Subsequently, a homogeneous distribution of high aspect ratio AlB2 flakes crystallized upon holding below the peritectic transition temperature. Growth rate in the (a) and (c) dimensions increased during elevated hold temperatures below the peritectic transition temperature. Surprisingly, faster cooling rates from above the liquidus to room temperature resulted in thinner, wider flakes. Similar to graphite this phenomenon is believed to result from a need to accommodate a changing misfit strain energy between the solidifying aluminum and the growing AlB2 flakes.

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Suhara, Masahiko, and Koichi Mano. "NQR and Phase Transitions in Hexachlorocyclopropane Crystal." Zeitschrift für Naturforschung A 45, no. 3-4 (April 1, 1990): 339–42. http://dx.doi.org/10.1515/zna-1990-3-421.

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Abstract35Cl NQR and DSC studies on phase transitions in hexachlorocyclopropane (HCCP), C3Cl6 , are reported. It is found that HCCP has three solid phases: A high temperature disordered phase (Phase I) above 301 K (no NQR spectrum was observed); a metastable phase (Phase II), which exhibited 6 NQR lines from 77 to 270 K; a low temperature phase (Phase III) in which a 24-multiplet of 35Cl NQR lines at 77 K, the most complex multiplet spectrum ever reported was observed. DSC measurement shows a A-type transition at 301 K and a broad transition of very slow rate at 285 K. The structure and mechanism of phase transitions in HCCP crystal are discussed.

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38

Dogan, Mehmet, Sehoon Oh, and Marvin L. Cohen. "High temperature superconductivity in the candidate phases of solid hydrogen." Journal of Physics: Condensed Matter 34, no. 15 (February 10, 2022): 15LT01. http://dx.doi.org/10.1088/1361-648x/ac4c62.

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Abstract As the simplest element in nature, unraveling the phase diagram of hydrogen is a primary task for condensed matter physics. As conjectured many decades ago, in the low-temperature and high-pressure part of the phase diagram, solid hydrogen is expected to become metallic with a high superconducting transition temperature. The metallization may occur via band gap closure in the molecular solid or via a transition to the atomic solid. Recently, a few experimental studies pushed the achievable pressures into the 400–500 GPa range. There are strong indications that at some pressure in this range metallization via either of these mechanisms occurs, although there are disagreements between experimental reports. Furthermore, there are multiple good candidate crystal phases that have emerged from recent computational and experimental studies which may be realized in upcoming experiments. Therefore, it is crucial to determine the superconducting properties of these candidate phases. In a recent study, we reported the superconducting properties of the C2/c-24 phase, which we believe to be a strong candidate for metallization via band gap closure (Dogan et al 2022 Phys. Rev. B 105 L020509). Here, we report the superconducting properties of the Cmca-12, Cmca-4 and I41/amd-2 phases including the anharmonic effects using a Wannier function-based dense k-point and q-point sampling. We find that the Cmca-12 phase has a superconducting transition temperature that rises from 86 K at 400 GPa to 212 K at 500 GPa, whereas the Cmca-4 and I41/amd-2 phases show a less pressure-dependent behavior with their T c in the 74–94 K and 307–343 K ranges, respectively. These properties can be used to distinguish between crystal phases in future experiments. Understanding superconductivity in pure hydrogen is also important in the study of high-T c hydrides.

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39

Bykova, Elena, Maxim Bykov, Vitali Prakapenka, Zuzana Konôpková, Hanns-Peter Liermann, Natalia Dubrovinskaia, and Leonid Dubrovinsky. "High-pressure behavior of Fe2O3." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C49. http://dx.doi.org/10.1107/s2053273314099501.

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High pressure behavior of Fe2O3has been a long-standing subject of research due to its high importance for understanding Earth's interiors. At pressures from 40 to 60 GPa it undergoes a series of transformations, such as structural changes with a large volume discontinuity (~10 %), a drop of the resistivity, a spin crossover of Fe3+, and a disappearance of the ordered magnetic state. The crystal structure of the phase(s) observed on compression at ambient temperature above 50 GPa is still under question since only powder X-ray diffraction (XRD) data were available so far. Mössbauer and Raman spectroscopy studies cannot provide definitive structural information. Applying laser heating to Fe2O3, compressed up to 70 GPa and above, results in a distinct reconstructive phase transition to the CaIrO3-type structure, according to powder XRD. Poverty of the available structural data encouraged us to perform a series of high-pressure and high-temperature XRD experiments on single crystals of Fe2O3in diamond anvil cells. We have studied the behavior of Fe2O3at pressures up to 100 GPa and temperatures up to 2500 K. Here we report crystal structures of two novel high-pressure Fe2O3polymorphs, as well as the relations between a spin state of iron atoms and the crystal chemistry of the iron compound. In our compression experiments initially hematite-structured Fe2O3transformed to a new phase at ~54 GPa with 10 % of the volume reduction. This phase has a triclinic distorted perovskite-type structure. The second reconstructive transition occurred at 66–70 GPa with 3 % of the volume discontinuity and resulted in formation of an orthorhombic phase. Laser heating to ~21001100 K at pressures above 70 GPa promoted a transition to a Cmcm CaIrO3-type phase, whose crystal structure was refined by means of single crystal XRD to R1~ 9.7 %. Decompression experiments showed that the Cmcm phase transforms back to hematite at pressures between ~25 and 15 GPa.

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40

Huang, Yuan, Jie Yang, Zi-jian Li, Kun Qian, and Feng Sao. "High-temperature ferroelastic phase transition in a perovskite-like complex: [Et4N]2[PbBr3]2." RSC Advances 9, no. 18 (2019): 10364–70. http://dx.doi.org/10.1039/c9ra00804g.

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A new lead-bromide hybrid organic–inorganic complex [Et₄N]₂[PbBr₃]₂ (Et = ethyl) was synthesized, and its crystal structures could be described as a distorted perovskite-like one and a step-like dielectric anomaly was obtained at around 375/367 K.

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Arafat, S. S. "Structural transition and magnetic properties of high Cr-doped BiFeO3 ceramic." Cerâmica 66, no. 378 (June 2020): 114–18. http://dx.doi.org/10.1590/0366-69132020663782802.

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Abstract Magnetic properties of BiFe1-xCrxO3 perovskite-type solids reaction synthesized at high pressure were investigated and a magnetic phase diagram was established. X-ray diffraction data revealed a crystal structure transformation from rhombohedral to monoclinic as Cr3+ ions substituted Fe ions in the samples. Néel temperature TN and spin-reorientation temperature TSR were determined from dM/dT by measuring the temperature dependence of magnetization (M-T). The magnetization results indicated that TN and TSR were strongly dependent on Cr3+ ion doping; both TN and TSR decreased with the increase of Cr3+ doping. The magnetic hysteresis loops investigated at room temperature reflected an antiferromagnetic behavior from x= 0.4 to 0.6 and weak ferromagnetic at x=1.0. Besides, the remnant magnetization Mr and maximum magnetization Mmax increased with increasing x from 0.4 up to 1.0. The Cr doping was found to be helpful in reducing coercivity Hc for the magnetic samples from x= 0.4 to 0.8 and their applications as magnetic sensors are possible.

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42

SUGAHARA, MASANORI, and NICKOLAI N. BOGOLUBOV. "HIGH-TEMPERATURE SUPERCONDUCTIVITY CAUSED BY CIRCULAR POLARIZED ZERO-POINT OSCILLATION." Modern Physics Letters B 15, no. 08 (April 10, 2001): 219–24. http://dx.doi.org/10.1142/s0217984901001525.

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A new model is proposed on the recently found non-cuprate high temperature superconductivity in crystal with 2D conduction plane which is composed of the planar connection of many circular localized orbits. Our findings are as follows: (i) the ground state of the doped 2D particle system in zero point oscillation is similar to the particle state in very strong magnetic field, (ii) Laughlin state with filling factor ν = 1/2 is the most stable state of the 2D particle system, (iii) the superposition of many fluctuating Laughlin states in pure crystal gives a coherent state with superfluidity. (iv) This model gives an estimation of the upper limit of the superconductivity transition temperature: [Formula: see text] for fcc C 60, and [Formula: see text] for Ag β Pb 6 CO 9, which are close to observation.

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Igartua, J. M., A. Faik, I. Urcelay-Olabarria, and E. Iturbe-Zabalo. "Crystal structures and high-temperature phase transition of Sr2MSbO6(M= Sc, Cr, Fe) double perovskites." Acta Crystallographica Section A Foundations of Crystallography 64, a1 (August 23, 2008): C546. http://dx.doi.org/10.1107/s0108767308082457.

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44

Yamada, Takahiro, Takuji Ikeda, Ralf P. Stoffel, Volker L. Deringer, Richard Dronskowski, and Hisanori Yamane. "ChemInform Abstract: Synthesis, Crystal Structure, and High-Temperature Phase Transition of the Novel Plumbide Na2MgPb." ChemInform 45, no. 30 (July 10, 2014): no. http://dx.doi.org/10.1002/chin.201430004.

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45

Ma, Shaonian, Yanping Xu, Yuxi Pang, Xian Zhao, Yongfu Li, Zengguang Qin, Zhaojun Liu, Ping Lu, and Xiaoyi Bao. "Optical Fiber Sensors for High-Temperature Monitoring: A Review." Sensors 22, no. 15 (July 30, 2022): 5722. http://dx.doi.org/10.3390/s22155722.

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High-temperature measurements above 1000 °C are critical in harsh environments such as aerospace, metallurgy, fossil fuel, and power production. Fiber-optic high-temperature sensors are gradually replacing traditional electronic sensors due to their small size, resistance to electromagnetic interference, remote detection, multiplexing, and distributed measurement advantages. This paper reviews the sensing principle, structural design, and temperature measurement performance of fiber-optic high-temperature sensors, as well as recent significant progress in the transition of sensing solutions from glass to crystal fiber. Finally, future prospects and challenges in developing fiber-optic high-temperature sensors are also discussed.

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46

Massalska-Arodź, M., A. Würflinger, and D. Büsinga. "High-pressure DTA Studies of the Phase Behaviors of 4-n -butyl-thiocyanobiphenyl (4TCB) and 4-w-pentyl-4’-n-phenyl-cyanocyclohexane (5HCP)." Zeitschrift für Naturforschung A 54, no. 12 (December 1, 1999): 675–78. http://dx.doi.org/10.1515/zna-1999-1202.

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Abstract DTA measurements of 4-n-butyl-thiocyanobiphenyl (4TCB) and ρ-cyano-ρ’-pentylphenyl-cyclohex-ane (5HCP) have been performed in the temperature range 220 K-390 K and pressures up to 400 MPa. For 4TCP a transition from a crystalline to a liquid crystal phase (probably smectic E) could be detect-ed at higher pressures > 90 MPa. The pressure dependence of the transition temperature has been estab-lished. At pressures lower than 88.7 MPa no transition of SmE into a crystal or into a glass has been found. For 5HCP only the melting curve was observed, in contrast to 5PCH, which displays a liquid crystalline nematic phase.

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47

Oh, I. H., M. Merz, S. Mattauch, and G. Heger. "Structural phase transition and hydrogen ordering of TlH2PO4 at low temperature." Acta Crystallographica Section B Structural Science 62, no. 5 (September 18, 2006): 719–28. http://dx.doi.org/10.1107/s0108768106018222.

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The crystal structure of TlH2PO4 (TDP) has been studied at low temperature. The lattice parameters were derived from high-resolution X-ray powder diffraction in the temperature range between 8 and 300 K. A detailed crystal structure analysis of the antiferroelectric low-temperature phase TDP-III has been performed based on neutron diffraction data measured at 210 K on a twinned crystal consisting of two domain states. The structure model in the triclinic space group P\bar 1 is characterized by a complete ordering of all the H atoms in the asymmetric O—H...O hydrogen bonds. The phase transition from the ferroelastic TDP-II to the antiferroelectric TDP-III phase at 229.5 ± 0.5 K is only slightly of first order and shows no detectable hysteresis effects. Its mechanism is driven by the hydrogen ordering between the partially ordered TDP-II state and the completely ordered TDP-III state. The polymorphism of TDP and the fully deuterated TlD2PO4 (DTDP) is presented in the form of group–subgroup relations between the different space groups.

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Wolf, Alexandra K., Jürgen Glinnemann, Martin U. Schmidt, Jianwei Tong, Robert E. Dinnebier, Arndt Simon, and Jürgen Köhler. "SiBr4 – prediction and determination of crystal structures." Acta Crystallographica Section B Structural Science 65, no. 3 (May 19, 2009): 342–49. http://dx.doi.org/10.1107/s0108768109012051.

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For SiBr4 no crystal structures have been reported yet. In this work the crystal structures of SiBr4 were predicted by global lattice-energy minimizations using force-field methods. Over an energy range of 5 kJ mol−1 above the global minimum ten possible structures were found. Two of these structures were experimentally determined from X-ray synchrotron powder diffraction data: The low-temperature β phase crystallizes in P21/c, the high-temperature α phase in Pa\overline{3}. Temperature-dependant X-ray powder diffraction shows that the phase transition occurs at 168 K.

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Yoshiasa, Akira, Akihiko Nakatsuka, Maki Okube, and Tomoo Katsura. "Crystal structure refinement of MgSiO3high temperature C2/c clinoenstatite." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C79. http://dx.doi.org/10.1107/s2053273314099203.

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The high-temperature clinoenstatite (HT-CEn) is one of the important MgSiO3 pyroxene polymorph. The single-crystal of C2/c HT-CEn endmember is firstly synthesized by rapid pressure-temperature quenching from 15-16 GPa and 900-19000C [1]. No report that it is produced as single crystal or large domain has been made on the MgSiO3 endmember. The HT-CEn-type modifications are observed in Ca-poor Mg-Fe clinoenstatite and pigeonite and are always found to be unquenchable in rapid cooling. The high pressure and high temperature experiments of MgSiO3 composition were carried out with a Kawai-type multi-anvil apparatus. The samples were quenched by rapidly releasing the oil pressure load and/or by blow out of anvil cell gasket. The space group of C2/c is strictly determined by Rigaku RAPID Weissenberg photographs and synchrotron radiation. Single-crystal X-ray diffraction experiments were performed at ambient conditions using a Rigaku AFC-5 four circle diffractometer. A total of 9383 reflections was measured and averaged in Laue symmetry 2/m to give 766 independent reflections used for the structure refinements. Final reliability factors converged smoothly to R = 0.029. The single-crystal diffraction analysis shows that the unusual bonding distances frozen in this metastable structure. The degree of kinking of the silicate tetrahedral chains is 1750for HT-CEn. The chain angle for HP-CEn is substantially smaller (1350) and the angle for L-CEn turned to the opposite direction at -1600(=2000). The degree of kinking increases by being curved in more than 1800in the transition from HT-CEn to L-CEn. As for the reverse change from the expansion to the stretch, a potential barrier exists in the point of the continuity. It is suggested that the reason which can quench structure under ambient conditions is the present HT-CEn single crystal was formed by the isosymmetric phase transition from HP-CEn. HT-CEn type single-crystals cannot be frozen without pressure.

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Tarakina, N. V., A. P. Tyutyunnik, T. V. Dyachkova, L. L. Surat, B. V. Slobodin, and V. G. Zubkov. "Crystal structure of RbBaVO4 and high-pressure modification of KCaVO4." Powder Diffraction 28, S2 (September 2013): S65—S74. http://dx.doi.org/10.1017/s0885715613001140.

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The crystal structures of KCaVO4 and RbBaVO4, synthesized at high-pressure/high-temperature and by a conventional solid-state reaction, respectively, were determined using X-ray powder diffraction data. These compounds were found to have the β-K2SO4 structure type (space group Pnma, Z = 4) with parameters a = 7.2628(5) Å, b = 5.7258(4) Å, c = 9.6854(7) Å (KCaVO4), and a = 7.8887(1) Å, b = 5.9589(1) Å, c = 10.3958(2) Å (RbBaVO4). The unit cell volume of KCaVO4, 402.77(5) Å3, is significantly lower than for the low-temperature modification reported previously, 436.2 Å3. The difference can be explained by a pressure-induced phase transition to a more dense state resulting from the rotation of tetrahedra and the exchange of oxygen atoms from the first and second coordination spheres for potassium and calcium atoms.

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Journal articles on the topic 'High temperature crystal structurephase transition'

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