Improved ferroelectric and piezoelectric properties of tape casted free standing PSLZT thick films

Abstract

We have synthesized Sr and La substituted Pb(1-x-3y/2)SrxLay(Zrz, Ti(1−z))O3 ceramics with x = 0.06, y = 0.01, 0.03, 0.05, z = 0.56 by solid-oxide route. Compacted discs were sintered at optimized temperature of 1280 °C for 2 h and its phase formation was confirmed by XRD analysis. Rietveld refinement confirmed that for the composition with y = 0.03 coexistence of tetragonal and rhombohedral phases comparatively closer to MPB. Dielectric and ferroelectric properties of discs were investigated thoroughly as a function of La content. Among the three compositions, ceramics with y = 0.03 (PSLZT) exhibit higher piezoelectric voltage coefficient (g33) of 30 mV.m/N which is relatively high compared to commercial PZT compositions. This composition was further utilized to fabricate free-standing piezoelectric thick films of 100 μm thickness using tape casting method with optimized slurry formulation. Warpage free PZT thick films with Pt electrodes were achieved with better density by co-sintering at 1060 °C for 2 h. Free standing thick films were characterized for their structural, microstructural, ferroelectric and piezoelectric properties and compared with bulk ceramic properties. The relative dielectric constant of 1250 with loss tangent of 0.02–0.03, remnant polarization of about 19 μC cm−2, piezoelectric charge coefficient of 300–325 pC/N and piezoelectric voltage coefficient up to 27 mV.m/N have been observed. These results indicate piezoelectric voltage coefficient of PSLZT free standing thick films is comparable to that of its bulk ceramic counterpart.