Characterisation of mixed potassium-barium mica glass-ceramics with varying fluorine content

Fifteen glasses with varying fluorine and potassium/barium contents designed to crystallise to fluorophlogopite have been investigated. The purpose of this investigation is to understand the nucleation and crystallisation behaviour of mica glass-ceramics. This will allow for new materials to be developed for engineering and dental applications. Compositions with high fluorine and potassium contents were shown to lower the glass transition temperature and promote crystallisation of fluorophlogopite by a bulk nucleation mechanism. Volatilisation of SiF₄ during heat treatment of the glasses was shown to occur by a surface loss mechanism. Fluorine deficient glasses crystallised to both fluorophlogopite and cordierite.