Grain size dependence of the microstructures and functional properties of (Ba0.85 Ca0.15–x Cex) (Zr0.1 Ti0.9) O3 lead-free piezoelectric ceramics

Abstract

By the solid-state reaction route, (Ba0.85Ca0.15-x Cex) (Zr0.1Ti0.9) O3 (BCCeZT) lead-free piezoelectric ceramics were prepared. The powder was processed at 1250 ºC for 2 h, and compacted green bodies were then sintered at various sintering temperatures. X-ray diffraction analysis and Raman spectra confirmed the rhombohedral-tetragonal phase coexistence of x = 0–0.00131. Addition of CeO2 facilitated development of grain sizes greater than 10 μm at low sintering temperatures. The effects of grain size on the ferroelectric and piezoelectric properties were studied systematically and it was found that a ~ (10–12) μm grain size is critical for the processing of high-performance lead-free BCCeZT ceramics. CeO2 substitution at the A site may bring down the sintering temperature by about 200 °C without significant loss of properties. The best properties were obtained for x = 0.00131 at a low sintering temperature of 1350°C for 4 h exhibiting d33 = 501 ± 10 pC/N, kp = 38.5 ± 1.92 %, Pr = 12.19 μC/cm2, TC = 108.1°C, and a large strain of 0.14%. These results show that BCCeZT ceramics could be promising candidates for the fabrication of lead-free devices.

Keywords

• Lead-free ceramics
• sintering
• grain size
• piezoelectric properties
• micro- structure