The determination of the crystallinity in glass-ceramic materials by the method of Ruland

The method of Ruland [Acta Cryst. (1961). 14, 1180-1185] for the determination of crystallinity has been modified in order to take account of a difference in chemical composition of the crystallized and non-crystallized fractions, such as occurs in glass-ceramic materials. Application to two samples leads to higher crystallinities than found by other X-ray methods, and shows a large increase of disorder with decreasing crystallinity.