Antiferrodistortive phase transition in EuTiO3

Autor(en)

Veronica Goian, Stanislav Kamba, Oliva Pacherová, Jirí Drahokoupil, Lukáš Palatinus, M. Dusek, Jan Rohlícek, Maxim Savinov, František Laufek, Wilfried Schranz, Armin Fuith, M. Kachlík, Karel Máca, Andrey Shkabko, Leyre Sagarna, Anke Weidenkaff, Alexei A. Belik

Abstrakt

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 (3) over barm to tetragonal I4/mcm due to antiphase tilting of oxygen octahedra along the c axis (a(0)a(0)c(-) in Glazer notation). The phase transition is analogous to SrTiO3. However, 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 similar or equal to 0.38 a*. 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.

Organisation(en)

Physik Funktioneller Materialien

Externe Organisation(en)

Czech Academy of Sciences, Czech Geological Survey, Brno University of Technology, Eidgenössische Materialprüfungs- und Forschungsanstalt, National University Corporation Tsukuba University of Technology

Journal

Physical Review B

Band

86

Anzahl der Seiten

9

ISSN

1098-0121

DOI

https://doi.org/10.1103/PhysRevB.86.054112

Publikationsdatum

2012

Peer-reviewed

Ja

ÖFOS 2012

103015 Kondensierte Materie, 210006 Nanotechnologie, 103018 Materialphysik, 103029 Statistische Physik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/ed49b697-1b96-4db2-aa17-f7c012a0fdd9