Crystallization kinetics of fluorophosphate glasses: Part I Effect of composition and heating rate

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Crystallization behaviour of glasses from the system AlF3−MF2−Ba(PO3)2 (M=Ca, Mg, Sr, Ba) have been studied using differential thermal analysis as a function of Ba(PO3)2. The kinetic parameters for crystallization, namely, the activation energy, E, frequency factor, ν, and Avrami exponent, n, were determined. E, ν and n decreased with increasing Ba(PO3)2. Crystallization commenced at higher temperatures and the crystal growth mechanism changed from bulk to surface with increasing Ba(PO3)2. X-ray diffraction analysis revealed that CaAlF5, SrAlF5, CaAlF7 and CaSrAlF7 crystallize from these glasses when heated. The infrared transmission spectra indicated that AlF6, PO3F and Ba(Ca,Mg,Sr)P2O7 groups were present in these glasses.

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