Electrical Properties and Phase Transition Behavior of (Li,Na,Ba)(Nb,Ti)O_3 Lead-Free Piezoelectric Ceramics

摘要

The electrical properties and phase transition behavior of the sodium niobate-based solid solution (l-x)Li_0.12Na_0.88NbO_3-xNa_0.91Ba_0.09Nb_0.91Ti_0.09O_3 [(1-x)LNN12-xNNBT9] ceramics were investigated. The lattice constant changes became discontinuitous between LNNBT0.5 and LNNBT0.7. Moreover, the peak dielectric constant of LNNBT0.7 is twice that of LNNBT0.5. X-ray diffraction analysis and dielectric study confirmed that the different crystal phases of what are LNN-type rhombohedral (x=0), LNN-type orthorhombic (x=0.1.l, 0.3 and 0.5), NNBT-type orthorhombic (x=0.7 and 0.9) and NNBT-type tetragonal (x= 1.0) phases. An electromechanical coupling factor of 0.244 was obtained for LNNBT0.7 whose composition is near the boundary between the LNN-type and NNBT-type orthorhombic phases.