The intermediate range order of metaphosphate glasses by X-ray diffraction

Abstract

Metaphosphate glasses containing the metal ions Me=Li, Na, K, Ag, Mg, Ca, Co, Zn, Sr, Cd, Ba, Pb, Al, La have been studied by X-ray diffraction. Information on the intermediate range structure of the glasses is extracted from the main peak in the structure factors, S( s), possibly occurring prepeaks, scattering effects in the small angle range and the zero-angle scattering intensity. Most of the glasses studied develop a quasi-periodic superstructure in the intermediate range scale indicated by a first diffraction peak in S( s). The constitution of the superstructure is based on different principles governed by the type of metal ion present in the glass. A mixed oxide effect was found to exist for ternary metaphosphate glasses of the Na 2O–BaO–P 2O 5 system but did not exist for the Na 2O–K 2O–P 2O 5 system. Small angle scattering effects are observed only in the S( s) functions of the Mg(PO 3) 2 glasses. The features of these scattering effects depend on the cooling conditions of the glass melt, and their appearance is correlated with the crystallization behaviour of the glasses.