We report, for the first time, the ionic conductivity properties of two polymorphic structures of bismuth molybdates: Bi0.55MoO4 and Bi2(MoO4)3. A Bi0.55MoO4 single crystal was first synthesized, presenting a surprisingly high bismuth deficiency compared to the known stoichiometric phase Bi2(MoO4)3. It is expected to have a good oxide ion conduction due to the presence of Bi deficiency and oxygen vacancies. Bi0.55MoO4 crystallizes in the tetragonal system, space group I41/a with a = b = 5.239(2), c = 11.567(5) Å, and Z = 4. While Bi2(MoO4)3 crystallizes in the monoclinic space group P21/n, with unit cell parameters a = 7.71500(10), b = 11.5101(2), c = 11.1237(2) Å, β = 103.3640(10)°, and Z = 4. Taking an advantage over many other ionic conductors, the crystals do not undergo any clear structural phase transition below their melting points. The oxide ion conductivities of Bi0.55MoO4 and Bi2(MoO4)3 were measured to be 6.5 × 10-5 S cm-1 and 1.1 × 10-6 S cm-1 at a temperature of 400 °C, respectively.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics