Effect of Sr²⁺doping on the phase transition of BaTiO₃lead-free ferroelectric ceramics

The single phase Ba1-xSrxTiO3 (x = 0, 0.4, 0.8) ceramic compositions were fabricated through solid state (mixed oxides) method calcined at 850 °C and sintered at 1200 °C in air. The XRD patterns revealed the single phase BaTiO3 composition with a space group of pm-3m. The shifting of the (1 0 0) XRD peak to higher 2θ values is accredited to the substitution of comparatively smaller ion of Sr2+ (1.4 Å) for larger Ba2+ (1.6 Å) ion following the Braggs diffraction law (2dsinθ = mλ). The phase transition or Curie point from polar ferroelectric phase to non-polar paraelectric phase of Ba1-xSrxTiO3 was reported to decrease with increasing Sr2+ content in Ba1-xSrxTiO3 compositions. The value of the dielectric constant decreased with increasing the content of Sr2+, which may be attributed to the substitution of comparatively smaller ion of Sr2+ for Ba2+ in the perovskite structured Ba1-xSrxTiO3.