Abstract
Polarized Raman measurements were carried out in a 3% Ca- doped BaTiO3 (BCT) single crystal and compared with those in undoped BaTiO3 (BT) in order to study the effect of Ca2+ incorporation into the BT lattice. Spectra recorded at room temperature in BCT show peaks unexpected by the Raman selection rules in BT, proving an off-centering of Ca with respect to the Ba site in BT. Main phonon lines A1 polarized along the ferroelectric c axis are notably shifted to lower frequency by Ca doping, while the phonons E in the plane normal to c are nearly unaffected. In addition, the modes A1 are highly anharmonic, even more than in BT, as revealed by the temperature dependences of their frequency and damping which are analyzed in terms of 3rd and 4th order anharmonic potential.
Published Version
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