Anomalous elastic behavior of relaxor ferroelectric Ca0.28Ba0.72Nb2O6:Ce studied by resonant ultrasound spectroscopy

Elastic behavior of tetragonal tungsten bronze uniaxial relaxor ferroelectric cerium doped Ca0.28Ba0.72Nb2O6 single crystal was investigated employing resonant ultrasound spectroscopy in the temperature range from room temperature up to 1323 K. Doping of cerium lowers the phase transition temperature Tc and Burns temperature Tb significantly, however, intermediate characteristic temperature T* (between the Burns temperature Tb and the temperature of maximum dielectric permittivity Tm) remains same as for pure Ca0.28Ba0.72Nb2O6. All independent elastic constants evolved differently with temperature, reflecting their coupling to different types of the reorientational motion of the polar nanoregions through their interaction with the acoustic waves.