High-temperature conductivity and structure of Y2(WO4)3 ceramics

Abstract

The magnitude and character of conductivity were studied for Y₂(WO₄)₃ ceramics synthesized by the ceramic (from oxides) and organic-nitrate procedures. Investigation of the dependence \(\sigma \left( {{\alpha _{{o_2}}}} \right)\) and measurements of the ion transport numbers of charge carriers by the EMF method showed that Y₂(WO₄)₃ is basically an ion conductor. The conductivity is largely determined by the sample preparation conditions related to the dependence of the specific surface area and powder grain size on the synthetic procedure. The maximum high-temperature conductivity of Y₂(WO₄)₃ was 2.51 × 10^–4 S/cm, which roughly corresponds to the conductivities of Sc₂(WO₄)₃ and In₂(WO₄)₃ measured under the same conditions. It was confirmed that Y₂(WO₄)₃ crystallizes as a mixed monoclinic-orthorhombic structure at 1000°C. The character of water incorporation in hydrated Y₂(WO₄)₃ crystals was studied by thermogravimetry and diffuse reflectance IR spectroscopy. A qualitative model of water intercalation was suggested.