Formation of Li3B7O12and O2BF4phases from glass system of 0.5LiF-0.5B2O3containing P2O5and their structural properties

Borate glass containing lithium fluoride doped with different ratios of phosphate units was produced by conventional melting-annealing technique. Moreover, the produced samples were subjected to two steps of controlled heat treatment in order to achieve the glass-ceramic derivatives (nucleation and crystal growth regimes). Thermal expansion technique revealed that the nucleation temperature for the studied glasses is around 340 degrees C and the softening temperature (crystal growth) is around 432 degrees C to form glass-ceramic samples. Li(3)B(7)O(12)phase was observed as primary phase for the glass-ceramic samples. Also, other crystalline phases such as LiPO(3)and O(2)BF(4)were formed. Structural changes of both of the glass and the glass-ceramics were investigated through the Fourier transform infrared technique (FTIR). The active range in the FTIR which distinguishes the glass and the crystalized sample is lying from 400 to 1250 cm(-1). The presence of LiF in B(2)O(3)network changes the characteristic units of BO(3)and BO(4)units into BO2F and BO3F units, respectively.