Structural evolution, relaxation behaviors and dielectric properties of BaTiO3–BiAlO3 perovskite solid solutions

Abstract

The polycrystalline (1 − x)BaTiO3–xBiAlO3 ((1 − x)BT–xBA) (x = 0–0.15) ceramics are fabricated via a conventional solid state reaction method. X-ray diffraction and Raman results show a structural evolution from a tetragonal phase to a cubic one with increasing x. Dielectric studies exhibit a diffuse phase transition characterized by a strong temperature and frequency dispersion of permittivity. The dielectric maxima temperature Tm decrease, due to the strong interaction of Bi3+ and Al3+ with Ba2+ and Ti4+. (1 − x)BT–xBA ceramics underwent a ferroelectric to relaxor transition at x = 0.06. Activation energy with dozens meV is obtained using the Vogel-Fulcher relationship, which is attributed to thermally activated off-center ion hopping. Raman spectra of the (1 − x)BT–xBA ceramics at 264 cm−1, the paraelectric and cubic phase exist in the ceramics, so the polarization-electric plots are in the form of narrow ellipsoids with the elevation of x. Meanwhile, the discharged energy density of 0.85BT–0.15BA is 0.16 J/cm3.