Formation of medium-range order in fluoride glasses

A possible solution to the problem of determining the medium-range order in fluoride glasses is proposed. The model of the formation of the glass network is advanced on the basis of the complex-cluster model for salt melts and the percolation hypothesis. The determination of the glass network topology reduces to the: experimental determination of the percolation point and the geometric estimation of the second coordination number of a glass-farmer. It is shown that the functionalities of glass-formers as determined from both the percolation point and the crystal chemical constraints turn out to be identical.