Sapphire dilatometer cell for measuring the thermal expansion of solids.

Capacitive-based dilatometry is used to determine the thermal expansion of solid specimens over a broad temperature range and for the study of structural and thermodynamic phase transitions. It can detect length changes of 0.1 Å or better. Dilatometer cells have been constructed of metals, such as copper or silver, and non-metals, such as silicon and fused silica. Sapphire is a good candidate for the construction of a dilatometer cell. It has excellent thermal conductivity, a well-behaved thermal expansion of moderate magnitude, especially below ∼60 K, and is readily available. The design, fabrication, and testing of a sapphire dilatometer cell are described herein.