CaTiO 3 induced ferroelectric phase coexistence and low temperature dielectric relaxation in BaTiO 3 –BaZrO 3 ceramics

The series of 0.86BaTiO 3 –(0.14− x )BaZrO 3 – x CaTiO 3 (abbreviated as BT – BZ – x CT ) ceramics with 0.03 ≤  x  ≤   0.11 were studied to obtain high piezoelectric properties. Rietveld refinement analysis indicated that the BT – BZ – CT compositions follow a gradual rhombohedral ( R ) → orthorhombic ( O ) +  R  →  O  + tetragonal ( T ) →  T phase transformation with increasing x . Clear evidence of the series of ferroelectric phase transitions was also found in the dielectric results. The R ‐ O and O ‐ T transition temperature shifted close to ambient temperature, while the Curie temperature slightly increased with increasing x . In addition to the dielectric loss peaks associated with the structural phase transitions, a broad low‐temperature dielectric loss peak was detected in the R phase at T  =   90‐150 K. This dielectric relaxation was attributed to the domain wall freezing and fits well to the Vogel‐Fulcher model with activation energy E a  ≈ 60‐300 meV and freezing temperature T VF  ≈ 75‐140 K. High piezoelectric strain coefficient ( d 33 *) of about 1030 pm/V at 10 kV was achieved at x  =   0.07, and a high Curie temperature ( T C ) was maintained at about 375 K.