Phase transitions and electrical/optical properties in (1-x)KNbO3-x(Ba0.5Bi0.5)(Nb0.5Zn0.5)O3 ceramics

Doping- and temperature-induced phase transitions and optical/electric-properties for (1- x )KNbO 3 - x (Ba 0.5 Bi 0.5 )(Nb 0.5 Zn 0.5 )O 3 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 KNbO 3 . These results help in understanding the control of the structure, optical and electrical properties in KNbO 3 -based ferroelectric oxides.