Dielectric, ferroelectric, and piezoelectric properties in potassium sodium niobate ceramics with rhombohedral-orthorhombic and orthorhombic-tetragonal phase boundaries

A new phase boundary with rhombohedral-orthorhombic and orthorhombic-tetragonal phase boundaries is designed in (K0.48Na0.52)NbO3 by adding Bi0.5(Na0.7K0.2Li0.1)0.5ZrO3 (BNKLZ), where Zr4+ and (BNKL)2+ are respectively used to improve the temperature of a rhombohedral phase and to decrease the temperature of an orthorhombic-tetragonal phase coexistence. These ceramics endure several continuous phase transitions with increasing BNKLZ content, i.e., an orthorhombic phase (0≤x<0.03), orthorhombic-tetragonal phases (x=0.03), orthorhombic-tetragonal and rhombohedral-orthorhombic (O-T and R-O) phase existence (0.03