Competing effects of Ca doping on the phase transition and related properties in (Ba_1-xCa_x)(Ti_0.95Sn_{0 .05})O₃ ceramics

We present the competing effects of isovalent Ca doping into A-site on the properties of Ca-doped Ba(Ti,Sn)O-3 ceramics. (Ba1-xCax)(Ti0.95Sn0.05)O-3 (BCTS) ceramics with 0 <= x <= 0.06 were fabricated to investigate whether the increase in tetragonality, polarization and Curie temperature by Ca incorporation, which have been observed in Ca-doped BaTiO3 ceramics, would also occur in BCTS ceramics. We characterized the crystal structural, dielectric, and ferroelectric properties of the BCTS ceramics and strengthened ferroelectricity by the Ca incorporation was confirmed in the BCTS ceramics. However, at the same time, the BCTS ceramics exhibited a diffuse phase transition owing to the simultaneous occupation of the A- and B-sites, as evidenced by the unconventional trend of the critical exponent in the dielectric response and a monotonous decrease in strain hysteresis with increasing Ca content. We present a detailed analysis of these properties and propose competing roles of Ca doping in BCTS ceramics in detail.