Muon spin relaxation study of phosphosilicate gels

Muon dynamics in phosphosilicate proton conductors P2O5-SiO2 with a composition 30 mol% phosphorus oxide (30P) have been studied as a function of temperature using muon spin relaxation. For materials heat treated at 300 degrees C the muons implant at sites close to P-OH groups associated with water molecules. While in 1000 degrees C heat treated samples the muons are trapped at sites involving a bridging oxygen P-O-Si. Averaging of the local nuclear dipolar field by dynamics of the adsorbed water is observed above ca 180 K for the muon sites in the 300 degrees C heat treated sample. There is some evidence for further muon dynamics in this material above 250 K perhaps caused by muon diffusion.