Processing, microstructure and piezoelectric properties of Li-doped BCZT ceramics

Li2CO3 is a promising additive to reduce the sintering temperature for (Ba0.85Ca0.15) (Zr0.1Ti0.9)O3 (BCZT) ceramics, however, the solubility of Li2CO3 in water and the high volatility of Li2O at elevated temperatures make the processing and densification of BCZT-Li2CO3 ceramics (known as BCZT-L) challenging. In our work, an optimized processing route was developed to obtain dense and flat BCZT-L ceramics made with 0–10 mol% of Li2CO3 and involving sintering at 1300 °C–1400 °C. The chemical and structural evolution of BCZT-L ceramics during sintering with and without a BCZT powder bed are comprehensively documented and the distribution of Li in the matrix has been observed through TOF-SIMS to explain the effects of Li doping on the piezoelectric properties. The d33 and kp of BCZT-L initially increased with Li content, but then decreased with excess Li. The decreased d33 and kp with excess Li is associated with Li aggregation in the BCZT matrix.