Optimum Conditions for Preparation of High-Performance (Ba0.97Ca0.03)(Ti0.94Sn0.06)O3 Ceramics by Solid-State Combustion

The effects of calcination conditions (950A degrees C to 1200A degrees C for 2 h to 6 h) and sintering temperature (1300A degrees C to 1500A degrees C for 2 h) on phase formation, microstructure, and electrical behavior of lead-free piezoelectric (Ba0.97Ca0.03)(Ti0.94Sn0.06)O-3 (BCTS) ceramics produced by solid-state combustion using glycine as fuel have been investigated. BCTS powder with pure perovskite structure was obtained by calcination at 1100A degrees C for 4 h. The microstructure of the BCTS powders showed almost spherical shape with average particle size increasing from 184 nm to 320 nm as the calcination temperature and soaking time were increased. The XRD patterns of all ceramics exhibited single perovskite structure. Rietveld refinement analysis indicated that the BCTS ceramics exhibited coexistence of orthorhombic and tetragonal phase in all samples with increased tetragonal phase content with increasing sintering temperature. The average grain size, density, dielectric constants at room (epsilon (r)) and Curie temperature (epsilon (C)), remanent polarization (P (r)), and piezoelectric constant (d (33)) increased as the sintering temperature was increased up to 1400A degrees C, then decreased. BCTS ceramic sintered at 1400A degrees C exhibited the highest relative density (98%), highest dielectric response (epsilon (r) = 4951, epsilon (C) = 19,185), good ferroelectric behavior (P (r) = 12.74 mu C/cm(2) and coercive field E (c) = 1.60 kV/cm), and highest d (33) value (528 pC/N). The large piezoelectricity of BCTS ceramics makes them good candidates for use in lead-free applications to replace Pb-based ceramics.