Protonic conductivity measurements were performed on W12-xH3+xPVxO40•nH2O single crystals, where x was 1, 2 or 3. The analysis of Arrhenius plots suggested that the conductivity increased with increasing temperature; with 2 distinct linear regions. The activation energy in the first region decreased with increasing V concentration. There was a general trend towards increasing room-temperature conductivity with increasing V concentration. Steady-state photoconductivity measurements, at various illumination levels, indicated the existence of a continuous distribution of localised states in the materials.

Protonic and Photoconductivity Studies of Heteropolyanion Single Crystals. D.P.Padivan, S.J.Ethilton, R.Murugesan: Physica Status Solidi A, 2001, 185[2], 231-46