Thermal Expansion of Synthetic β‐Spodumene and β‐Spodumene—Silica Solid Solutions

Synthetic β‐Spodumene and several β‐Spodumene‐silica solid solutions were prepared, and their thermal expansion behavior was studied using high‐temperature X‐ray diffraction techniques. Data indicate that all β‐Spodumenes are characterized by a pronounced anisotropy of thermal expansion much the same as that of the silica polymorph keatite. Anisotropy increases slightly and the volume expansion decreases as the compositions become richer in SiO 2 . Specimens with more than 80.8 wt% SiO 2 at 130O°C and 1 atm contain P‐cristobalite along with β‐Spodumene. The lattice parameters of β‐Spodumene compositions throughout the solid solution range were determined. The structural aspects of the anisotropy of thermal expansion are discussed.