Structural and electrical properties of hexavalent-substituted BIMEVOX synthesized by a microwave-assisted route

The microwave (MW)-assisted solid synthesis route was employed to prepare a new Aurivillius-type compound with the general formula Bi₂Cr _x V_1?x O_5.5+x?δ; 0≤x≤0.20 (BICRVOX). This novel synthesis method revealed that polycrystalline products of the BICRVOX system can effectively be obtained after being irradiated for 25 min rather than for the many hours of high-temperature heating needed in other conventional routes. The phase structure of MW-prepared samples was characterized by comparison with those obtained from the conventional solid-state reaction, using powder X-ray diffraction, FT-IR and differential thermal analysis techniques. Importantly, the substitution of Cr(VI) for V(V) in the parent compound resulted in stabilization of only the α - and β -phases. AC impedance spectroscopy confirmed that the MW-prepared samples possess slightly lower oxide-ion performance compared with the conventionally-prepared ones; it did, however, evidence the significant role of powerful dielectric heating of MWs in lowering the charge carrier accumulation.