Phase transitions and electrical/optical properties in (1-x)KNbO₃-x(Ba_0.5Bi_0.5)(Nb_0.5Zn_0.5)O₃ ceramics

Doping- and temperature-induced phase transitions and optical/electric-properties for (1-x)KNbO₃-x(Ba_0.5Bi_0.5)(Nb_0.5Zn_0.5)O₃ ceramics are studied. With the increase of x-value, a series of structural phase transitions from orthorhombic to tetragonal and to cubic is observed, and the phase transition temperatures are also improved for forming a stable phase. The deteriorated ferroelectric property, which also suggests the doping-induced phase transition due to the enhancement of the crystal symmetry, can be tentatively interpreted from the optical evolution with doping. This doping can introduce or enhance the bandedge- or in-gap states but without influence upon the optical bandgap of KNbO₃. These results help in understanding the control of the structure, optical and electrical properties in KNbO₃-based ferroelectric oxides.