scholarly journals The crystallographic phase transition for a ferric thiosemicarbazone spin crossover complex studied by X-ray powder diffraction

2006 ◽  
Vol 30 (11) ◽  
pp. 1621-1627 ◽  
Author(s):  
Sébastien Floquet ◽  
Nathalie Guillou ◽  
Philippe Négrier ◽  
Eric Rivière ◽  
Marie-Laure Boillot
Keyword(s):  
Phase Transition ◽  
Powder Diffraction ◽  
Spin Crossover ◽  
X Ray

High-temperature X-ray powder diffraction study of the tetragonal-cubic phase transition in nanocrystalline, compositionally homogeneous ZrO2–CeO2 solid solutions

2008 ◽  
Vol 23 (S1) ◽  
pp. S70-S74 ◽  
Author(s):  
L. M. Acuña ◽  
R. O. Fuentes ◽  
D. G. Lamas ◽  
I. O. Fábregas ◽  
N. E. Walsöe de Reca ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Temperature ◽  
Powder Diffraction ◽  
Solid Solutions ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray ◽  
First Order

Crystal structure of compositionally homogeneous, nanocrystalline ZrO2–CeO2 solutions was investigated by X-ray powder diffraction as a function of temperature for compositions between 50 and 65 mol % CeO2. ZrO2-50 and 60 mol % CeO2 solid solutions, which exhibit the t′-form of the tetragonal phase at room temperature, transform into the cubic phase in two steps: t′-to-t″ followed by t″-to-cubic. But the ZrO2-65 mol % CeO2, which exhibits the t″-form, transforms directly to the cubic phase. The results suggest that t′-to-t″ transition is of first order, but t″-to-cubic seems to be of second order.

Dynamic proton disorder and the II–I structural phase transition in (NH4)3H(SO4)2

2009 ◽  
Vol 65 (1) ◽  
pp. 36-44 ◽  
Author(s):  
Yoo Jung Sohn ◽  
Anja Loose ◽  
Michael Merz ◽  
Karine Sparta ◽  
Helmut Klapper ◽  
...  
Keyword(s):  
Phase Transition ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Powder Diffraction ◽  
Structural Phase ◽  
Local Symmetry ◽  
Crystal Structure Analysis ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Proton Disorder

X-ray powder diffraction, differential scanning calorimetry (DSC)/thermogravimetry (TG) and single-crystal neutron diffraction methods were used to investigate triammonium hydrogen disulfate (NH4)3H(SO4)2 (TAHS) in the temperature range between 293 and 493 K. The temperature-dependent X-ray powder diffraction measurements show a clear hysteresis of the I \leftrightarrow II phase transition of TAHS with transition temperatures of T up = 412.9 (1) K on heating and of T down = 402.6 (1) K on cooling. From the existence of hysteresis and from the jump-like changes of the lattice parameters, the I \leftrightarrow II phase transition of TAHS is considered to be first order. With DSC/TG measurements we confirmed that there is only one phase transition between 293 and 493 K. Through careful investigation on single crystals of TAHS using neutron diffraction, the correct space group (C2/c) of room-temperature TAHS-II phase was confirmed. Crystal structure analysis by single-crystal neutron diffraction showed a strongly elongated displacement ellipsoid of the proton which lies in the middle of the (SO4)H(SO4) dimer with \bar 1 local symmetry. The protons of the NH4 groups also show strongly enlarged anisotropic mean-square displacements. These findings are interpreted in terms of a characteristic proton disorder in the TAHS-II phase.

X-ray Powder Diffraction Structure Reinvestigation of the α and β Forms of Cobalt Phthalocyanine and Kinetics of the α → β Phase Transition

1998 ◽  
Vol 120 (49) ◽  
pp. 12798-12807 ◽  
Author(s):  
Paolo Ballirano ◽  
Ruggero Caminiti ◽  
Claudio Ercolani ◽  
Adriana Maras ◽  
Maria Antonietta Orrù
Keyword(s):  
Phase Transition ◽  
Powder Diffraction ◽  
Cobalt Phthalocyanine ◽  
X Ray ◽  
Β Phase ◽  
Diffraction Structure ◽  
Kinetics Of

Structural phase transition in GaMo4Se8 and AlMo4S8 by X-ray powder diffraction

1992 ◽  
Vol 200 (1-4) ◽  
Author(s):  
Μ. François ◽  
Ο. V. Alexandroν ◽  
K. Yvon ◽  
H. Ben Yaich-Aerrache ◽  
P. Gougeon ◽  
...  
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
Powder Diffraction ◽  
Structural Phase ◽  
X Ray

High-Temperature Synchrotron X-Ray Powder Diffraction Study of the Orthorhombic–Tetragonal Phase Transition in La0.63(Ti0.92,Nb0.08)O3

2002 ◽  
Vol 164 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Roushown Ali ◽  
Masatomo Yashima ◽  
Masahiko Tanaka ◽  
Hideki Yoshioka ◽  
Takeharu Mori ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Diffraction Study ◽  
Powder Diffraction ◽  
Tetragonal Phase ◽  
X Ray ◽  
Tetragonal Phase Transition
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