TY - JOUR
T1 - Charge density distributions of strontium titanate obtained by the maximum entropy method
AU - Ikeda, T.
AU - Kobayashi, T.
AU - Takata, M.
AU - Takayama, T.
AU - Sakata, M.
N1 - Funding Information:
The authors thank T. Mori for his kind help in data collection at Photon Factory. This work was supported by Photon Factory, KEK under the proposal No. 95G125, partly by a Grant-in-aid for Scientific Research from the Ministry of Education, Science and Culture in Japan for which the authors' thanks are due.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 1998/5/1
Y1 - 1998/5/1
N2 - Strontium titanate (SrTiO3) shows a displacive phase transition at 110 K. In order to study electron level structural changes throughout the phase transition, the charge density distributions of SrTiO3 were obtained by applying the Maximum Entropy Method (MEM) to X-ray diffraction data at Room Temperature (R.T.) and 70 K. From the MEM charge densities at R.T., it was found that Ti-O shows a rather strong covalent bond and that no covalency of Sr atoms was detected, which means that the Sr atom exists as an ion. From these results, chemical bonds of SrTiO3 could be described as the Sr ion floating electro-statically between three dimensional Ti-O networks. The symmetry of the lattice changes through the 110 K phase transition, which causes the super-lattice reflection at the R point. The displacement of oxygen atoms throughout the phase transition can be easily seen by taking the difference in charge density distribution between these two temperatures. The MEM charge densities at 70 K reveal that the structural changes throughout the phase transition are rather small, that is, the Ti-O strong covalent bond is maintained. The nature of the chemical bond of Sr atoms is basically unchanged.
AB - Strontium titanate (SrTiO3) shows a displacive phase transition at 110 K. In order to study electron level structural changes throughout the phase transition, the charge density distributions of SrTiO3 were obtained by applying the Maximum Entropy Method (MEM) to X-ray diffraction data at Room Temperature (R.T.) and 70 K. From the MEM charge densities at R.T., it was found that Ti-O shows a rather strong covalent bond and that no covalency of Sr atoms was detected, which means that the Sr atom exists as an ion. From these results, chemical bonds of SrTiO3 could be described as the Sr ion floating electro-statically between three dimensional Ti-O networks. The symmetry of the lattice changes through the 110 K phase transition, which causes the super-lattice reflection at the R point. The displacement of oxygen atoms throughout the phase transition can be easily seen by taking the difference in charge density distribution between these two temperatures. The MEM charge densities at 70 K reveal that the structural changes throughout the phase transition are rather small, that is, the Ti-O strong covalent bond is maintained. The nature of the chemical bond of Sr atoms is basically unchanged.
KW - Displacive phase transition
KW - Perovskite compound
KW - Synchrotron radiation
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U2 - 10.1016/s0167-2738(98)00033-2
DO - 10.1016/s0167-2738(98)00033-2
M3 - Article
AN - SCOPUS:0032074471
VL - 108
SP - 151
EP - 157
JO - Solid State Ionics
JF - Solid State Ionics
SN - 0167-2738
IS - 1-4
ER -