Analysis of a Magnesium-containing: β-Eucryptite Solid Solution by the Lattice Constant Method and Its Application

Abstract

Abstract An X-ray diffraction method has been developed for the determination of the composition of a magnesium-containing β-eucryptite solid solution which consists of a pseudo-ternary system, SiO2–Mg1⁄2AlO2–LiAlO2. Standard samples of the solid solution within the range of 60–75 mol% SiO2 and 0–15 mol% Mg1⁄2AlO2 were prepared from high-purity materials by the “glass-crystallization” technique. The diffraction angles of the (206) and (212) planes were measured from the center of gravity of the profile recorded on a chart by a counter diffractometer. After having been corrected for various systematic errors, both angles were used for the calculation of the lattice constants. It was found that Mg1⁄2AlO2 and LiAlO2 contributed similarly to a0, but in a different way to c0. The composition of the solid solution in a commercial glass-ceramic could be determined from the correlation between the composition and the lattice constants. The standard deviation of the determination from one measurement was about 0.2–0.4 mol%, and the time required for analysis was about 30 min.