Effect of Ni addition on PNZT tungsten bronze structure

Lead niobate zirconate titanate (PNZT) with general formula 0.5PbNb₂O₆–0.5Pb(Zr_xTi_1-x)O₃ (where x = 0.15, 0.25, 0.35) and lead nickel niobate zirconate titanate (PNNZT) with general formula Pb(Ni_xNb_0.5-xZr_0.25Ti_0.25)O₃ (where x = 0.167, 0.250, 0.333) have been prepared by conventional solid state reaction. The phase formation has been studied by X – ray diffraction analysis. Raman investigations have been carried out in the 200–1000 cm⁻¹ wave number range. The structural changes observed in the X – ray diffraction pattern has been further confirmed by Raman analysis. The major changes in the E(1TO), A₁(1TO) and E + B₁ phonon modes suggest the structural change from cubic to rhombohedral with increase in Ni concentration in PNNZT. The optical band gap has been calculated from UV – Vis absorption spectra.