Synthesis and Electrical Properties of a Fluorite-Like Nd5Mo3O16 Compound with Partial Substitution of Molybdenum by Tungsten, Niobium, or Vanadium

Resumo

The phase formation of Nd₅Mo_{3 – x}W_xO_16.5, Nd₅Mo_{3 – x}Nb_xO_{16.5 – х/2}, and Nd₅Mo_{3 – x}V_xO_{16.5 – х/2} solid solutions based on a fluorite-like Nd₅Mo₃O_16.5 compound (mixed conductor with interstitial oxygen conductivity) has been studied. The electrical conductivity of doped compounds obeys the Arrhenius law and, at a low impurity content, is as high as 0.03–0.08 S/cm at 800°C. Substitution of Mo⁶⁺ cations by V⁵⁺ and Nb⁵⁺ cations reduces the interstitial oxygen content, which causes a decrease in the solid-solution electrical conductivity by 1–2 orders of magnitude and a decrease in the cubic unit-cell parameter. A wide diffuse anomaly with a maximum of about 1500–4000 has been observed in the temperature dependence of the permittivity for all single-crystal and polycrystalline samples in the range of 300–900°C.