Oxynitride phosphate glasses have been obtained by thermal treatment under ammonia atmosphere of metaphosphate glasses with the composition xLi2O.(25-x)Na20.25Pb0.50P205 (x=0, 12.5, 25). The kinetics of nitrogen incorporation in the temperature range of 600-700 deg C, and the influence of the temperature over the nitridation for differing processing times have been studied. The viscosity of the base phosphate glasses has been determined in the 250-800 deg C temperature range, and has been related with the processing parameters, temperature and time. A comparative study of the nitridation kinetics, as well as the maximum nitrogen contents reached in several base glass compositions, has revealed the relationships between all parameters that affect the nitridation process.
