Semiconducting vanadium phosphate glasses

V2O5–P2O5 glasses containing less than 10 mol% of P2O5 are prepared by splat-cooling. They crystallize upon heating above 200°C leading to orthorhombic solid-solutions. ESR of V4+ in these glasses shows that short range order around vanadium is about the same in the glasses as in orthorhombic V2O5, but the hopping frequency of the small polarons decreases when P2O5 increases leading to an “Anderson localization” of the charge carriers. These results agree with those already obtained with the usual V2O5–P2O5 glasses containing more than 10% of P2O5.