Synthesis, Structural and Raman Investigations of PbNi1/3Nb2/3O3 Ceramics

The Pb(Ni1/3Nb2/3)O-3 (PNN) ceramics was synthesized by two different methods, viz. (i) single step and (ii) double step. Phase formation of powders prepared by both the methods at various temperatures and lead excess were analyzed by X-ray diffraction (XRD) and Raman scattering experiments. The studies revealed that for single step method the unreacted phases diminished with increase of firing temperature and only impure nickel niobate phase remained at 1200 degrees C. Addition of 4 wt% excess lead oxide reduced the impure nickel niobate phase concentration from 8.9% to 4.2% for the single step method. Addition of 2 wt% excess lead oxide was found sufficient to remove pyrochlore nickel niobate phase for double step method. Temperature dependent XRD showed pure phase throughout the temperature range of 35 to 350 K indicating the stability of the phase formed. The Raman study also confirmed the formation of pure perovskite phase.