Raman and infrared spectra of KNbO3 in niobate glass-ceramics

Potassium niobophosphate glasses and glass-ceramics of the family [xNb(2)O( 5).(50-x)P2O5. 50K(2)O]:yFe(2)O(3) were studied by x-ray powder diffraction , infrared and Raman scattering spectroscopy. For the potassium-phosphate s amples [50P(2)O(5)-50K(2)O] the iron oxide presents a network former behavi our, for 2 mol% of Fe2O3 doping. The precipitation of crystalline K4Nb6O17 and ferroelectric KNbO3 crystals was confirmed by x-ray powder diffraction in the samples with x = 40 and 50 mol% respectively. The infrared and Raman scattering spectroscopy results suggest that the increase of the ratio Nb2 O5/P2O5 leads the niobium to sites of octahedral symmetry and consequently to the formation of ferroelectric KNbO3, as seen by x-ray diffraction analy sis.