X-ray diffraction, dielectric, pyroelectric, piezoelectric and Raman spectroscopy studies on (Ba_(0.95)Ca_(0.05))_(0.8875)Bi_(0.075)TiO_3 ceramic

摘要

The ((Ba_(0.95)Ca_(0.05))_(0.8875)Bi_(0.075)TiO_3 ceramic composition was prepared using the conventional mixed-oxide technique. X-ray diffraction at room temperature and dielectric permittivity in the temperature range from 85 to 450 K and frequency range from 10~2 to 2 x 10~5 Hz, respectively, were studied. The X-ray spectra were investigated by profile refinement technique with the use of specialized software at room temperature, the ((Ba_(0.95)Ca_(0.05))_(0.8875)Bi_(0.075)TiO_3 composition crystallizes in quadratic perovskite structure. The dielectric measurements show classical ferroelectric behavior. The pyroelectric and piezoelectric results confirm the dielectric measurements. The pyroelectric coefficient is about 69.2 nC/cm~2 K at the transition temperature (T_C = 367 K). The piezoelectric constant is d_(31) = 31.1 pC/N and the electromechanical coupling factor is k_P = 0.14679. Raman spectra of ((Ba_(0.95)Ca_(0.05))_(0.8875)Bi_(0.075)TiO_3 ceramic were taken at various temperatures and measured over the wave number range from 50 to 1000 cm~(-1). All the Raman bands were assigned as the transitional modes of Ba～(2+), Ca～(2+), Bi～(3+) and Ti~(4+) cations. The temperature evolution of Raman spectra across the transition shows an important evolution characterizing the disorder of the high temperature phase.