Raman Spectra and Dielectric Studies in Ti Substituted Bi2 (Zn2/3Nb4/3)O7 Pyrochlores.

Bi₂Zn_2/3-x/3Nb_4/3-2x/3Ti_xO₇ (m - BZNT) with x = 0 to 0.4 were synthesized in the conventional solid state route. The dielectric constants of these ceramics at microwave frequencies are found to be increasing from 70 to 114 when x increased from 0 to 0.4. Raman scattering studies were carried out to investigate the effect of Ti⁴⁺ substitution on the dielectric properties of Bi₂(Zn_2/3Nb_4/3)O₇ (m-BZN) ceramics. The observed Raman peaks in the m-BZNT are slightly shifted towards lower frequency in comparison to that of m-BZN clearly indicated that the Ti⁴⁺ ions are indeed occupying substitution sites in the host m - BZN. The anomalous change in intensity and full with at half maxima (FWHM) of Raman modes at 749 and 847 cm^-1 suggest change in oxygen octahedral closely related to dielectric properties of m-BZNT. [ABSTRACT FROM AUTHOR]