Studies on optical and electrical properties of synthesized polycrystalline CdMoO₄ and PbMoO₄

Abstract

Molybdates of Cd(II) and Pb(II) were synthesized by chemical route. The formation of CdMoO₄ and PbMoO₄ was confirmed by chemical analysis and powder X-ray diffraction (XRD) studies. Single-phase nature and purity of the molybdates was ascertained by matching their XRD data with the JCPDS data file. The powdered form of these molybdates was transformed into pellets under desired pressure using polyvinyl alcohol (PVA) as a binder. The polycrystalline pellets of these materials were then sintered at 900°C for 30 h. These molybdates in polycrystalline pel1et form were characterized with respect to diffused reflectance studies, D.C. electrical conductivity and thermoelectric power measurements.

The optical band gap values for CdMoO₄ and PbMoO₄ were calculated from their reflectance measurements and found to be 2.14 eV and 2.94 eV, respectively. The D.C. electrical conductivity for the pellets of these molybdates was studied over the temperature range 300-600 K. Plot of log(<i>ϭ</i>) vs. (1/<i>T</i>) showed the semiconducting nature of these materials and clearly indicate a break corresponding to temperatures 408 K and 465 K, respectively,

for CdMoO₄ and PbMoO₄. The activation energies below and above this break temperature have been estimated as 1.84 eV and 4.00 eV for CdMoO₄ and 2.46 eV and 8.63 eV for PbMoO₄.