Structure and electrical properties of SrZrO3-modified (K,Na,Li)(Nb,Ta)O3 lead-free piezoelectric ceramics

In this work, SrZrO3 was used as a dopant for KNN-based lead-free piezoelectric ceramics with composition of (K0.49Na0.49Li0.02)(Nb0.8Ta0.2)O-3 (denoted by KNLNT) to optimize their piezoelectric and dielectric properties. SrZrO3-modified KNLNT lead-free piezoelectric ceramics were synthesized via a conventional solid-state method. The effects of doping on crystal structure, ferroelectric properties, dielectric properties and piezoelectric properties were systematically investigated. The transformation of the crystal structures of the ceramics from orthorhombic to tetragonal has been monitored and the coexistence of orthorhombic and tetragonal phases has been identified with the range of 0.01-0.03 for the doping SrZrO3. The doping of SrZrO3 was found to be effective in reducing the grain sizes and lowering the orthorhombic-tetragonal phase transition point temperature (T (O-T)) and Curie temperature (T (C)) in SrZrO3-modified KNLNT ceramics. The optimized content of SrZrO3 is 0.02, in which the maximum d (33) of 156 pC/N can be obtained, corresponding to the disappearance of T (O-T) and T (C) of 252.5 A degrees C.