LAUSR

ABSTRACT (Na0.5K0.5)(Nb0.8Ta0.2)O3 lead-free ceramics with variation of alkaline metal elements were investigated. It has been found that the phase transition temperature of the ceramics can be widely adjusted by A-site doping. Li+ doping could increasing TC, while other alkaline metal elements Na+, K+, Rb+ and Cs+ doping couldn't stabilize orthorhombic phase. TC increased to 377°C from the initial 306°C as the Li+ amount increasing from 0.02 to 0.10, meanwhile, TO-T decreased from 82°C to −38°C. It is indicated that TC can be influenced by tolerance factor t. An enhanced d33 = 185 pC/N and kp = 44% at room temperature were observed in the ceramics with Li+ content of x = 0.04, probably because the corresponding TO-T of the ceramics is moved to room temperature at x = 0.04 Li+ amount. The enhanced piezoelectric properties indicate that the modified (Na0.5K0.5)NbO3 lead-free materials are promising candidates to complement Pb(Zr,Ti)O3 based solid solutions on certain occasions and the expanded phase-transition temperature range can be beneficial to the service circumstances of the materials.