Raman spectra and dielectric studies in Ti substituted Bi < inf > 2 < /inf > (Zn < inf > 2/3 < /inf > Nb < inf > 4/3 < /inf > )O < inf > 7 < /inf > pyrochlores

Abstract

Bi2Zn2/3-x/3Nb4/3-2x/3TixO7 (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 (Zn2/3Nb4/3)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.