Phase Formation, Structure, and Dielectric Properties of Modified Potassium Sodium Niobate Ceramics

We have prepared (1 – x)(K0.5Na0.5)NbO3–xCa(Cu1/3Nb2/3)O3 (x = 0–0.1, ∆х = 0.02) ceramics by solid-state reactions and studied their phase formation, structure, and dielectric and ferroelectric properties. The formation of a phase with the perovskite structure and an orthorhombic unit cell has been demonstrated in all of the samples. Ferroelectric phase transitions have been confirmed by dielectric spectroscopy and laser second harmonic generation measurements. The temperatures of the phase transitions from the orthorhombic ferroelectric phase to the tetragonal ferroelectric phase and to the cubic (paraelectric) phase have been shown to decrease with increasing x. We have analyzed the composition dependences of dielectric parameters in the system studied.