Structural Study of Semiconducting Silver Vanadate Glasses by Means of Low-Temperature Mössbauer Spectroscopy

Abstract

⁵⁷Fe-Mössbauer measurements of semiconducting silver vanadate glasses were performed at temperatures ranging from 78 to 298K. It proved that Fe³⁺ ions, incorporated into the vanadate glasses as a Mössbauer probe, are present at substitutional sites of tetrahedral V⁵⁺ or V⁴⁺ ions. Absorption area vs. temperature plot for 5Ag₂O⋅85V₂O₅⋅10Fe₂O₃ and 45Ag₂O⋅45V₂O₅⋅10Fe₂O₃ glasses gives two straight lines with different slopes, which correspond to the Debye temperatures of 344 and 279K. These results indicate that an introduction of Ag₂O into V₂O₅ matrix results in a gradual change of the glass matrix from a two-dimensional layer structure, originally composed of VO₅ tetragonal pyramids, to a chain structure composed of VO₄ tetrahedra. It is concluded that glass matrix of silver vanadate glasses is essentially the same as that of alkali (Li, Na and K) vanadate glasses. Silver vanadate glasses will have fewer nonbridging oxygen (NBO) atoms than alkali vanadate glasses.