Borate, lithium borate, and borophosphate powders by sol-gel precipitation

Abstract

Borate, lithium borate and borophosphate powders were synthesized by the sol-gel method. Triethyl borate, lithium methoxide, and orthophosphoric acid were used as precursors for B2O3, Li2O, and P2O5, respectively. Powders were characterized by FTIR, DTA, XRD and SEM techniques. Powders from the Li2O-B2O3 system exhibited glassy features while borate and borophosphate powders contained mainly crystalline B2O3 according to XRD analysis. However, a 500 degrees C heat treatment transformed these crystalline powders into glass powders. Conversely, heat treatment of Li2O-B2O3 powders transformed their structure from glassy to crystalline (Li2B4O7). Chemical durability studies conducted in water at 60 degrees C showed that minor additions of P2O5 into borate and lithium borate powders improved their chemical durability significantly. Furthermore, Li2O and P2O5 acted synergistically on the chemical durability when added simultaneously to borate compositions.