Temperature-Dependent Phase Transitions in the Lead-Free Piezoceramics (1-x - y)(Bi1/2Na1/2)TiO3-xBaTiO(3)-y( K0.5Na0.5)NbO3 Observed by in situ Transmission Electron Microscopy and Dielectric Measurements
JOURNAL OF THE AMERICAN CERAMIC SOCIETY, v.96, no.10, pp.3312 - 3324
Abstract
Lead-free piezoelectric (1-x-y)(Bi1/2Na1/2)TiO3-xBaTiO(3)-y(K0.5Na0.5)NbO3 (BNT-BT-KNN) ceramics were examined in situ under increasing temperature in the transmission electron microscope. Changing superstructure reflections indicate a transition from rhombohedral to tetragonal to cubic phase with broad coexistence regions. The additional evolution of the microstructure in combination with dielectric measurements leads to a model of two relaxor-type phase evolutions with temperature.