CONTRIBUTION TO THE CHEMICAL-ANALYSIS OF FLUOROPHOSPHATE GLASSES

Volatilisation from alkaline earth fluorophosphoaluminate glasses when heated above 550 degrees C hinders chemical analysis. Solution of thi s type of glass cannot, therefore, be effected using traditional fluxe s. Furthermore, the amount of oxygen in the vitrifiable mass is insuff icient to ensure stoichiometric conversion of all elements present int o their oxide forms. Thus the analytical results must be expressed in terms of the elements. The use of solution with mineral acids is also ruled out because of the release of hydrofluoric acid in the process. The work reported here covers the development of a method for the anal ysis of the glasses in these syst ems produced from high purity reagen ts. Specimens were melted ground and pelletised for analysis by x-ray fluorescence spectroscopy thus avoiding the need for solution. The two extreme compositions in the series were used as calibration standards . Al, Ca, Mg and P were quantified by inductively coupled plasma atomi c emission spectroscopy (ICP-AES); Ba was determined gravimetrically a nd F was measured by spectrophotometry following pyrohydrolytic distil lation. XRF analyses were supplemented by the determination of oxygen using a LECO differential analyser.