The devitrification of lithium metaborate: polymorphism and glass formation

The ambient pressure devitrification of glassy lithium metaborate has been studied by Raman and infrared spectroscopies. Of the three different polymorphs obtained, two are identified as α- and γ-LiBO 2, while a third one, β′-LiBO 2, is thought to consist of alternating borate triangles and tetrahedra respecting the metaborate stoichiometry (BO 2 -. The network of glassy LiBO 2 prepared by melt quenching consists mainly of local arrangements similar to those encountered in all three polymorphs in accordance with the ideas of Krogh-Moe. It is argued that the glass structure exhibits the memory of structural transformations occuring in the vicinity of T g , and may be described by models implying the existence of structural ‘granularity’.