Formation of Borophosphate Glass Structure Within the System BaO--B sub 2 O sub 3 --P sub 2 O sub 5

Formation of distinct crystalline phases during glass synthesis in the system BaO--B sub 2 O sub 3 --xP sub 2 O sub 5 (x = 0-60 mol%) has been predicted thermodynamically and verified by means of measured Raman spectra. The initial reaction temperature is reduced by 200-300 deg C on addition of P sub 2 O sub 5 to BaO--B sub 2 O sub 3 with the primary reaction product being BPO sub 4 . In addition, both borate and phosphate compounds including BaO.B sub 2 O sub 3 , BaO.4B sub 2 O sub 3 , 3BaO.P sub 2 O sub 5 and 2BaO.P sub 2 O sub 5 have been identified in compositions containing up to 33 mol% P sub 2 O sub 5 . Raman spectra reveal the appearance of orthophosphate groups and compositions analogous to the compound 2BaO.B sub 2 O sub 3 .P sub 2 O sub 5 . All binary compounds were observed in mixtures having a P sub 2 O sub 5 content between 30-33 mol%; associated Raman spectra exhibit marked line broadening. At higher phosphate compositions meta- and ultra-phosphate phases could be identified from measured spectra. Graphs, Phase diagrams, Spectra. 33 ref.--AA