The pure perovskite (Li0.06Na0.47K0.47)NbO3 lead-free piezoelectric powders were synthesized by the developed sol-gel method, in which Nb2O5 was transformed into a water-soluble niobate by a chemical chelation method as the Nb source. After calcinations at different temperatures between 500 and 650 ℃, the mean particle size of the (Li0.06Na0.47K0.47)NbO3 powders was changed from 20 to 60 nm. The effect of grain size on the phase structure of the (Li0.06Na0.47K0.47)NbO3 nano powders was investigated. The results demonstrated that, as the grain size of the (Li0.06Na0.47K0.47)NbO3 decreased from 60 to 20 nm, the phase structure was transformed from orthorhombic to tetragonal, which can be attributed to the nano-size effect. Further, it can be expected that the tetragonal-cubic phase transition would occur at the size less than 20 nm at room temperature.

Key words: soluble niobate, sol-gel method, lead-free piezoelectric ceramic, grain size, phase structure