Preparation and Properties of Glass‐Ceramics Derived from Nitrogen‐Containing β‐Spodumene Glasses

Crystallization of Li‐Al‐Si‐O‐N oxynitride glasses based on the β‐spodumene composition and the properties of the resultant glass‐ceramics have been studied. The onset of the precipitation of metastable high‐quartz solid solution and its transformation to β‐spodumene shift to higher temperatures with increasing nitrogen content of the oxynitride glasses. Nitrided glass‐ceramics crystallized at 1200°C have negative thermal expansion coefficients, since high‐quartz structure is maintained up to 1000° and 1200°C. Knoop hardness and density of the glass‐ceramics increase with increasing nitrogen content. There was evidence that part of the nitrogen atoms were incorporated into the high‐quartz solid‐solution structure and that a small amount of the minor phase of Si 2 N 2 O was precipitated in highly nitrided glass‐ceramics.