Thermal Products in the Systems of NaPO₃-WO₃ and NaPO₃-Na₂WO₄

Abstract

A mixture of NaPO3 glass and tungsten trioxide or sodium tungstate with various. PIW ratios from O, 3 to 300 was heated at 10000C, . and the resulting melt was cooled r. aptd!y. All X-ray di raction peaks of the products of the NaPO3-WO3 system with P/W ratios from O 3to O.7 and those of the product of the NaPO3-Na2WO system with P/W ratio of O.3 are due to tungsten trioxide and sodium tungstate respectively, and the other products of both systems are. amorphous. lt was. revealed-by paper-chromatographic analysis that the average chain length of condensed phosphates present in the products increased with an increase of the P/W ratio. Therefore, it could be coneluded that NaPO3 glass reacts with tungsten trioxide or sodium tunqstate to form P O W linkage at 1000 C. The absorption near 900 cm-i in IR speetra of the products of the NaPO3-WOs and Na2WO systems may be attributed to, P-OW stretching. Assuming that the glassy products of the NaPOs-WOs and Na2WO4 systems with P/W ratios larger than 30 have P-O-P, P-O, P-O-W, and W-O linkages, a theoretical treatment of the degree of polymerization of condensed phosphate has been made and compared with the experimental data, and then reasonable structures of the products have been cdncluded as WO2(OP)2, WO2(OP)s, or WO2(OP)