Novel optical amorphous phosphate materials with a low melting temperature

We report on the synthesis of transparent amorphous hydrated phosphate materials at low temperatures (as low as 300 degrees C) in the [50P(2)O(5) - (25 - x/2 )K2O - (25 - x/2)Na2O - xZnO] - nH(2)O (0-25 mol%). These new transparent materials were studied by Raman and FTIR spectroscopies. The structure of the hydrated phosphates is proposed to consist of both short phosphate chains and isolated phosphate groups linked together by hydrogen bonds. Containing up to 40 mol% of water, most of the physico-chemical properties remain unchanged, except for the characteristic glass temperatures. Moreover, the most hydrated amorphous phosphate materials tend to exhibit a softening phenomenon below 150 degrees C. The addition of ZnO to these phosphate materials offers better glass stability against moisture while maintaining the glass properties of zinc-free materials. Hence, these new amorphous transparent materials pave the way for novel low melting temperature optical materials.