Effect of Nb2O5 content on dielectric characteristics of tungsten–bronze-structured KLN ceramics

The effect of excess Nb2O5 on the dielectric characteristics of tungsten–bronze-structured polycrystalline K3Li2Nb5O15 (KLN) ceramics was studied. During sintering, the evaporation of K and Li was inevitable, which caused an effective increase of Nb content in the crystal. Even though the initial composition was below the boundary, where the crystal structure of KLN changed from tetragonal to orthorhombic, the composition passed over the boundary due to evaporation. The composition shift took away the dielectric relaxation near the phase transformation temperature. Ti addition was effective in suppressing the evaporation of K and Li and revived the phase transformation. The evaporation of cations was explained from the viewpoint of lattice stability.