Structure, thermal stability and electrical conductivity of CaMoO4+δ

Single-phase tetragonal scheelite CaMoO4 (space group, Pmmm) was prepared via the conventional solid state reaction method. The oxidation state of the transition metal species for the as-sintered CaMoO4 was analyzed by X-ray photoelectron spectroscopy (XPS). The average thermal expansion coefficient was measured as about 11 × 10−6 K−1 over the temperature range of 303–1373 K. From the thermodynamic point of view, the phase diagram for CaMoO4 was constructed by computing the equilibrium phase boundaries. Finally, the electrical conductivity of CaMoO4 was also investigated by an AC impedance analyzer. The activation energy of bulk conductivity for CaMoO4 was 2.1 eV.