X-ray and dielectric studies of ferroelectric or relaxor phases in the Ca1−xNaxSn1−xNbxO3 system

Abstract Ceramics with composition Ca 1− x Na x Sn 1− x Nb x O 3 ( 0.85 ⩽ x ⩽ 0.96 ) were sintered in the temperature range 1200–1400 °C. Dielectric properties of ceramics belonging to the whole composition domain were investigated in a broad range of temperatures (80–600 K) and frequencies (0.1–200 kHz). The thermal behavior of the dielectric permittivity suggests the existence of three phases: cubic-paraelectric, tetragonal-paraelectric and orthorhombic-ferroelectric or relaxor. The relaxor, or classical ferroelectric character, is dependent on the value of x . The symmetries of these three phases were investigated by X-ray diffraction study. The polarization state was checked by piezoelectric and pyroelectric measurements.