Lead-free (Ba_0.85Ca_0.15)(Ti_0.9Zr_0.1)O₃-Y₂O₃ ceramics with large piezoelectric coefficient obtained by low-temperature sintering

Lead-free (Ba_0.85Ca_0.15)(Ti_0.9Zr_0.1)O₃-xwt.%Y₂O₃ (BCZT-xY) piezoelectric ceramics have been synthesized using solid-state reaction technique and the effects of Y₂O₃ addition on the phase structure and piezoelectric properties of the ceramics have been studied. The results reveal that the addition of Y₂O₃ significantly improves the sinterability of BCZT ceramics, resulting in a reduction of sintering temperature from 1,540 to 1,350 °C, and an increase of the Curie temperature T _C from 85 to 95 °C. X-ray diffraction data shows that Y₂O₃ diffuses into the lattice of BCZT-xY ceramics and a pure perovskite phase forms in the ceramics. Scanning electron microscopy images indicate that a small amount of Y₂O₃ addition affects the microstructure, obviously. Main piezoelectric parameters of these ceramics are optimized around x = 0.06 wt % with a large piezoelectric coefficient (d ₃₃  = 560 pC/N), a high planar electromechanical coefficient (k _p  = 53 %) and a low dissipation factor (tan δ = 0.9 %) at 1 kHz. The results indicate that the BCZT-xY ceramics are promising lead-free materials for practical applications.