Electron and Nuclear Magnetic Resonance in Semiconducting Phosphate Glasses

Paramagnetic vanadium-phosphate and molybdenum-phosphate glasses have been studied using electron-spin resonance and nuclear magnetic resonance. These glasses were nominally 80% MO:20% P2O5, where MO denotes the transition-metal oxide. The electron-spin-resonance results showed a strongly exchanged, narrowed interaction with V4+/V5+ and Mo5+/Mo6+ ratios and line shapes which were independent of temperature over the range 77°–300°K. Since the conductivity is nonlinear in this temperature range, the result is direct evidence that the mobility is temperature dependent and that the average paramagnetic-site is unchanged over this temperature range. The nuclear magnetic resonance of 51V and 31P in the glasses verifies the assumption of exchange narrowing. The 51V quadrupole coupling (1.5 MHz) and spin-lattice relaxation time (T1<500 μsec) were temperature independent over the 77°–300°K range. The 31P resonances in each of the glasses also had temperature-independent properties. For the molybdenum glass the linewidth was 0.45 G and T1=300 msec. For the vanadium glass the corresponding numbers were 1.4 G and <500 μsec. The results are compared in part with previously published values.