abstract
In order to inspect bulk properties of the SrTiO3 ceramics grains, dielectric permittivity and temperature shift of a zero-phonon R-emission line of the Cr (3+) impurity-ion probes were studied in sol-gel SrTiO3:Cr (3 x 10-2%) ceramics of the average grain size similar to 24 mu m. We found that non-dispersive permittivity ( 100 Hz to 1 MHz) increases on cooling less steeply than in single crystals reaching similar to 5000 at 30 K. At lower temperatures the dispersion appears and the permittivity saturates at similar to 8 K(epsilon'approximate to 7000, 400 Hz). However, the temperature shift of the R-line in ceramics remains practically identical to that for SrTiO3 single crystals, in which R-line shifts with temperature is Delta upsilon similar to 1/epsilon' similar to omega(2)(Tot). This indicates that the bulk of the grains in ceramics exhibits properties inherent to SrTiO3 quantum paraelectric, which agrees with the "generalized brick-wall" approach developed recently to describe polarization response of granular high permittivity materials. (C) 2007 Elsevier Ltd. All rights reserved.
keywords
SOFT PHONON MODES; LINE
subject category
Materials Science
authors
Trepakov, VA; Savinov, ME; Okhay, O; Tkach, A; Vilarinho, PM; Kholkin, AL; Gregora, I; Jastrabik, L
our authors
Andrei Kholkin
Principal Researcher
Oleksandr Tkach
Assistant Researcher
Olena Okhay
Post-Doc Fellowship