Abstract
Ceramic materials [Formula: see text]BNT–xNKN–yBFO were synthesized using a traditional solid-state reaction method. Ceramics were examined by X-ray diffraction, microstructural analysis and dielectric methods. The change in symmetry of the crystal lattice in [Formula: see text]BNT–xNKN–yBFO has a complex nature, which displays the presence of planar defects and compositional heterogeneity. In this system, two phase transitions occur: a morphotropic phase transition from the cubic to the rhombohedral phase occurs by the nucleation and growth type through the morphotropic region in the range of [Formula: see text]. The second phase transition occurs by spinodal decomposition of the rhombohedral phase into two phases with close cell parameters in the range of [Formula: see text]. A correlation relationship between the crystal structure, microstructure and dielectric properties in solid solutions of the system was shown.