Improved dielectric properties in pyrochlore type oxides: Ca3Sm3−xBixTi7Nb2O26.5 (x = 1.0, 2.0 or 3.0) by Bi substitution

Improved dielectric properties are observed in pyrochlore type oxides, Ca3Sm3−x BixTi7Nb2O26.5 (x = 1.0, 2.0 or 3.0) by Bi substitution. The dielectric constant increased with increasing Bi concentration. The dielectric constant obtained for Ca3Bi3Ti7Nb2O26.5 is 110, whereas, without Bi (Ca3Sm3Ti7Nb2O26.5) it is 62 at 100 kHz. The Powder X-ray diffraction analysis reveals that cubic pyrochlore type phase is formed for all the compositions. The experimental results further show that the formation of Bi substituted compounds is complete at a lower temperature than the compounds without Bi. Microstructure studies reveal that the grains formed are acicular when Bi is present in large amounts compared to cuboid grains in samples having no Bi.