Antiferrodistortive phase transition in EuTiO.sub.3./sub..

0380651 - FZÚ 2013 RIV US eng J - Journal Article
Goian, Veronica - Kamba, Stanislav - Pacherová, Oliva - Drahokoupil, Jan - Palatinus, Lukáš - Dušek, Michal - Rohlíček, Jan - Savinov, Maxim - Laufek, F. - Schranz, W. - Fuith, A. - Kachlik, M. - Maca, K. - Shkabko, A. - Sagarna, L. - Weidenkaff, A. - Belik, A.A.
Antiferrodistortive phase transition in EuTiO₃.
Physical Review. B. Roč. 86, č. 5 (2012), , "054112-1"-"054112-9". ISSN 1098-0121
R&D Projects: GA MŠMT LD12026; GA ČR GAP204/12/1163
Grant - others:AV ČR(CZ) AP0701
Program: Akademická prémie - Praemium Academiae
Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z10100521
Keywords : antiferrodistortive structure * phase transition * X-ray diffraction * infrared reflectivity * EuTiO₃
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.767, year: 2012
http://link.aps.org/doi/10.1103/PhysRevB.86.054112

X-ray diffraction, dynamical mechanical analysis, and infrared reflectivity studies revealed an antiferrodistortive phase transition in EuTiO3 ceramics. Near 300 K, the perovskite structure changes from cubic Pm¯3m to tetragonal I4/mcm. Some ceramics as well as single crystals of EuTiO3 show different infrared reflectivity spectra bringing evidence of a different crystal structure. In such samples, electron diffraction revealed an incommensurate tetragonal structure with modulation wave vector q~ 0.38aa*. Extra phonons in samples with modulated structure are activated in the IR spectra due to folding of the Brillouin zone. We propose that defects such as Eu3+ and oxygen vacancies strongly influence the temperature of the phase transition to antiferrodistortive phase as well as the tendency to incommensurate modulation in EuTiO3.
Permanent Link: http://hdl.handle.net/11104/0211303