Mo6+ Modified (K0.5Na0.5)NbO3 Lead Free Ceramics: Structural, Electrical and Optical Properties

Lead free polycrystalline ceramics (K0.5Na0.5)Nb(1−x)MoxO3 (x = 0, 0.02, 0.04, 0.06 and 0.08) have been synthesized via solid state reaction method. The formation of single phase perovskite structure up to 6 mol% of Mo6+ has been confirmed by X-ray diffraction pattern. Impedance spectroscopy reveals that bulk resistance decreases with increasing temperature, which indicates negative temperature coefficient of resistance (NTCR) behaviour of the compounds. The diffuse reflectance spectroscopy results indicate a red shift of the band gap energy of K0.5Na0.5NbO3 (KNN, from 4.28 to 3.61 eV) with increasing Mo6+ concentration due to structural modification. The photoluminescence spectra of doped samples are composed of two emission bands at room temperature. One emission band is near band edge ultraviolet (UV) emission (∼354 nm) and other is visible emission band (∼397 nm) which may explore the possibility of these ceramics to be used in optical device applications.