scholarly journals High-temperature phase transition of SrRuO3and SrHfO5: X-ray diffraction and PAC spectroscopy

1996 ◽  
Vol 52 (a1) ◽  
pp. C364-C364
Author(s):  
J. A. Guevara ◽  
S. L. Cuffini ◽  
Y. P. Mascarenhas ◽  
P. de la Presa ◽  
A. Ayala ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Pac Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Phase Transition

High-temperature single-crystal X-ray diffraction study of tetragonal and cubic perovskite-type PbTiO3phases

2016 ◽  
Vol 72 (3) ◽  
pp. 381-388 ◽  
Author(s):  
Akira Yoshiasa ◽  
Tomotaka Nakatani ◽  
Akihiko Nakatsuka ◽  
Maki Okube ◽  
Kazumasa Sugiyama ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Single Crystal ◽  
Diffraction Study ◽  
Relative Displacement ◽  
High Temperature Phase ◽  
Cubic Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray

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.

X-Ray Scattering Study of High Temperature Phase Transition of Betaine Phosphate

2004 ◽  
Vol 73 (4) ◽  
pp. 950-955 ◽  
Author(s):  
Katsuhiko Hasebe ◽  
Takanao Asahi ◽  
Takashi Yoshida ◽  
Yukihiko Kawamura ◽  
Hiroyuki Mashiyama ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray ◽  
X Ray Scattering ◽  
Temperature Phase Transition ◽  
Scattering Study ◽  
Ray Scattering

Phase Transitions and Distortion of [BiCl6]3– Octahedra in (C3H5NH3)3[BiCl6] – DSC and Single-Crystal X-Ray Diffraction Studies

2004 ◽  
Vol 59 (9) ◽  
pp. 1029-1034 ◽  
Author(s):  
Bartosz Zarychta ◽  
Maciej Bujak ◽  
Jacek Zaleski
Keyword(s):  
Phase Transition ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Unit Cells ◽  
Temperature Phase Transition ◽  
The Relationship ◽  
Low Temperature Phase ◽  
Disorder Type

The DSC diagram of tris(allylammonium) hexachlorobismuthate(III), (C3H5NH3)3[BiCl6], revealed three anomalies at 152, 191 and 299 K. The structure of the salt was determined at 200 and 315 K, below and above the high-temperature phase transition at 299 K. In both phases the crystals are monoclinic. At 200 K the space group is C2/c whereas at 315 K it is C2/m. The structures, at both temperatures, are composed of [BiCl6]3− octahedra and allylammonium cations. The organic and inorganic moieties are attracted to each other by a network of the N-H. . .Cl hydrogen bonds. The relationship between corresponding parameters of the unit cells has been found. The phase transition at 299 K, of the order-disorder type, is attributed to the ordering of one non-equivalent allylammonium cation in the low-temperature phase.

Synthesis and Characterization of Lithium Ion Conductors, Li3InBr6 and their Substituted Compounds

2005 ◽  
Vol 242-244 ◽  
pp. 17-26
Author(s):  
Yasumasa Tomita ◽  
Hideyoshi Matsushita ◽  
Yasuhisa Maeda ◽  
Kenkichiro Kobayashi ◽  
Koji Yamada
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Lithium Ion ◽  
Substitution Effect ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Li Ion ◽  
Lithium Ion Conductors

Li3-2xMxInBr6 (M=Mg, Ca, Sr and Ba) and Li3In1-xMxBr6 was synthesized, and thier substitution effect was investigated by means of 7Li and 115In NMR, X-ray diffraction and AC conductivity measurements. Phase transition was observed at 314 K in Li3InBr6 and fast Li+ diffusion was observed in the high temperature phase. Li3InBr6 has high Li+ ion conductivity and showed a little difference in X-ray diffraction patterns between the low-temperature phase and the high-temperature phase. These indicate that the sub-lattice for Li+ ions changed largely at the phase transition point and this change makes Li+ diffusion easily. In the high temperature phase of substituted compounds, the conductivity decreased with the amounts of substitution. and defects produced by the substitution with divalent cation did not contribute to the Li+ ion conduction. In the LT phase for Mg compound, the ionic conductivity increases up to x = 0.4 due to the introduction of the extrinsic vacancies.

Characterization of the time-dependentL-asparagine monohydrate crystal phase transition

2011 ◽  
Vol 44 (5) ◽  
pp. 954-957 ◽  
Author(s):  
A. S. de Menezes ◽  
F. M. Ardito ◽  
A. O. dos Santos ◽  
A. J. D. Moreno ◽  
R. J. C. Lima ◽  
...  
Keyword(s):  
Phase Transition ◽  
Annealing Time ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
Temperature Phase Transition ◽  
Asparagine Monohydrate

The high-temperature phase transition of single crystals of L-asparagine monohydrate was investigated by X-ray diffraction in association with Rietveld refinement and dilatometer measurements as a function of annealing time. The X-ray results showed that, for samples annealed at 343 K (or even 333 K) for 5 h, the expected anhydrous L-asparagine phase has been formed, monoclinic system (space groupP21), with lattice parametersa= 5.0677 (2),b= 6.7657 (2),c = 8.0742 (3) Å and β = 91.276 (4)°. The results obtained from measurements as a function of annealing time confirmed that the phase transition associated with loss of the water molecule is time dependent.

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