Crystallographic and dielectric properties of ferroelectric ceramics with compositions Na1−xAx(Nb1−xMgx)O3–3xF3x(A = Na, K)

Two new oxyfluoride ferroelectric solid solutions derived from NaNbO3 have been prepared; their compositions are the followings : Na1−xAx(Nbl-xMgx)O3−3xF3x with 0≤ × ≤0.15 for A = Na and 0≤ × ≤ 0.20 for A = K. The variations of both the symmetry and the unit cell parameters have been determined at room temperature. Dielectric measurements have been performed on ceramic samples in the temperature and frequency ranges 100 – 800 K and 102–105 Hz respectively. Each sample exhibits a maximum of ϵ′r at the Curie temperature TC.