Doping influence on structural ferroelectric phase transitions and electrical features of barium calcium titanate

We comprehensively report Sr, Cr, Mn, and Mg doping ions' influence on structural and dielectric properties of barium calcium titanate (BCT) ceramics over a wide temperature and frequency range. X-ray diffraction and electrical studies showed the phase transition (PT) from paraelectric (PE) to ferroelectric (FE) phase. The linear and nonlinear susceptibility measurement identified the discontinuous PT of BCT and Sr-doped BCT. Moreover, this measurement also distinguished diffused PE-FE PT features induced in BCT by the Cr and Mn ions. Exceptionally, the Mg ion doping caused the relaxor-like features in BCT. Distribution of relaxation times indicated a mixed order-disorder and displacive character of PT. The doping of Cr, Mn, and Mg ions shortened the relaxation times related to the B-sublattice ions jumping. We also confirmed low-temperature FE-FE PT via linear and nonlinear dielectric susceptibility and pyroelectric measurements. We showed that non-zero net polarization could be induced by an applied electric field.