Crystal Structure and the Paraelectric-to-Ferroelectric Phase Transition of Nanoscale BaTiO3

2008 ◽  
Vol 130 (22) ◽  
pp. 6955-6963 ◽  
Author(s):  
Millicent B. Smith ◽  
Katharine Page ◽  
Theo Siegrist ◽  
Peter L. Redmond ◽  
Erich C. Walter ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase

Features of Crystal Structure and Ferroelectric Phase Transitions of KTiOPO4 Doped with Nb and Sb

2004 ◽  
Vol 443-444 ◽  
pp. 303-306
Author(s):  
S.A. Ivanov ◽  
Sergei Yu. Stefanovich ◽  
S.-G. Eriksson ◽  
V.I. Voronkova ◽  
T.Yu. Losevskaya ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Structural Features ◽  
Neutron Powder Diffraction ◽  
Compositional Variation ◽  
Phase Transition Temperatures ◽  
Linear Optical Properties ◽  
Ferroelectric Phase Transitions

The evolution of the crystal structures as a function of temperature of the new solid- solution KTiOPO4 (KTP) isomorphs, namely K1-xNbxTi1-xOPO4 and K1-xSbxTi1-xOPO4 have been studied by neutron powder diffraction below and above the ferroelectric phase transition temperatures. On the basis of the experimental data obtained the cation distribution, among the sublattices of this structure, and the distortion of the framework at the phase transition, have been discussed. The possible correlation between the non-linear optical properties and the dominant structural features tailored by compositional variation has also been studied.

scholarly journals Structural Study of Ferroelectric Phase Transition of Sn-doped SrTiO3

2014 ◽  
Vol 70 (a1) ◽  
pp. C61-C61 ◽  
Author(s):  
Hirofumi Kasatani ◽  
Shoichiro Suzuki ◽  
Akira Ando ◽  
Eisuke Magome ◽  
Chikako Moriyoshi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Local Structure ◽  
Ferroelectric Phase Transition ◽  
Nearest Neighbor ◽  
Ferroelectric Phase ◽  
Rietveld Analysis ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray

Recently, ferroelectricity was discovered in Sn-doped SrTiO3 (abbreviated by SSTO), in which Sr-atom was substituted by a few percent Sn-atom[1]. The ferroelctricity of SSTO was confirmed by means of the appearance of the dielectric anomaly, that reached several thousands and the clear D-E hysteresis loop in low temperature phase. In order to clarify the mechanism of ferroelectric phase transition of SSTO from the viewpoint of the crystal structure, we investigated the average crystal structure and the local structure around the substitutional Sn-atom of SSTO10 (10% Sn concentration, ferroelectric phase transition temperature 180K) by means of synchrotron-radiation powder X-ray diffraction and transmission XAFS spectrum of Sn:K-edge, respectively. From the results of MEM/Rietveld analysis of powder X-ray diffraction data, it was obtained that crystal structure of paraelectric phase of SSTO10 was cubic perovskite structure with the disorder state of Sn-atom. In ferroelectric phase, the crystal system was tetragonal, which was similar in structure to tetragonal ferroelectric structure of BaTiO3, and Sn-atom was order state. XAFS study revealed that the valence of Sn-ion was +2 charge and the local structure of Sn-atom was seemed as being the self-insistent state of SnO crystal structure. However, strangely, the coordination number of the nearest neighbor atom, that is O-atom, was 2 instead of 4. This is a mystery result and we have been analyzing. We have considered that the ferroelectricity of SSTO is induced by the distortion around the subsitituional Sn-atom. At the meeting, we are planning to discuss the precise crystal structure and the mechanism of the ferroelectric phase transition of SSTO.

Ferroelectric phase transition in the whitlockite-type Ca9Fe(PO4)7; crystal structure of the paraelectric phase at 923 K

2004 ◽  
Vol 6 (2) ◽  
pp. 185-195 ◽  
Author(s):  
Bogdan I. Lazoryak ◽  
Vladimir A. Morozov ◽  
Alexei A. Belik ◽  
Sergey Yu. Stefanovich ◽  
Vadim V. Grebenev ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Paraelectric Phase

Incommensurate modulations of relaxor ferroelectric Ca0.24Ba0.76Nb2O6(CBN24) and Ca0.31Ba0.69Nb2O6(CBN31)

2014 ◽  
Vol 70 (4) ◽  
pp. 743-749 ◽  
Author(s):  
Heribert A. Graetsch ◽  
Chandra Shehkar Pandey ◽  
Jürgen Schreuer ◽  
Manfred Burianek ◽  
Manfred Mühlberg
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Tungsten Bronze ◽  
Orthorhombic Phase ◽  
Relaxor Ferroelectric ◽  
Tetragonal Symmetry ◽  
Tetragonal Tungsten Bronze

CBN crystals show a one- and a two-dimensionally modulated modification. The former is isotypic with orthorhombic Ba4Na2Nb10O30and the latter with the tetragonal tungsten bronze type of crystal structure. The orthorhombic form irreversibly transforms to the tetragonal polymorph at the ferroelectric phase transition near 603 K. Orthorhombic and tetragonal CBN24 slightly differ in the distribution of the Ba and Ca atoms over the incompletely filled Me1 and Me2 sites. The tetragonal symmetry is further broken in orthorhombic CBN24 by different amplitudes of the positional modulations of O atoms which are symmetrically equivalent in the TTB structure. A similar orthorhombic phase of CBN31 could be obtained by quenching from 1473 K.

Ferroelectric phase transition and crystal structure of the mixed crystals (NH4)2SO4-(NH4)2SeO4

1991 ◽  
Vol 120 (1) ◽  
pp. 271-280 ◽  
Author(s):  
M. L. Martinez Sarrion ◽  
A. Rodriguez Clemente ◽  
L. Mestres Vila ◽  
A. Lozano Merida ◽  
X. Solans
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Mixed Crystals
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