Remarkable piezoelectric performance and good thermal stability of-textured 0.96(K0.5Na0.5)(Nb1−ySby)O3-0.04SrZrO3 lead-free piezoelectric ceramics

Abstract

A 0.96(K0.5Na0.5)(Nb1−ySby)O3-0.04SrZrO3 [KN(N1−ySy)-SZ] thick films with 0.045 ≤ y ≤ 0.08 were textured along the [001] direction using NaNbO3 (NN) templates. A 3.0 mol% NN seed-added KN(N1−ySy)-SZ thick film with y = 0.055 exhibited a large Lotgering factor of 97% and d33 value of 502 pC/N. This thick film had an orthorhombic-pseudocubic polymorphic phase transition structure. Rietveld analysis revealed that the pseudocubic structure was similar to the R3m rhombohedral structure. The proportion of the pseudocubic phase in this thick film was significantly lower than that of the orthorhombic phase. The proportion of the pseudocubic phase increased with increasing Sb2O5. A 3.0 mol% NN seed-added KN(N0.935S0.065)-SZ thick film (y = 0.065) exhibited a large d33 value of 620 pC/N because it had similar proportions of orthorhombic and pseudocubic structure. The large d33 value (≥580 pC/N) was maintained up to 110 °C, indicating that this thick film exhibits excellent thermal stability. Furthermore, the thick films with 0.045 ≤ y ≤ 0.055 are expected to be good candidates for piezoelectric energy harvesters (PEHs) because they exhibited large d33 × g33 values (≥19.3 pm2/N), which represent the figure of merit of a PEH.