The thermal expansion of amorphous arsenic

Abstract

The linear thermal expansion of amorphous arsenic (a-As) has been measured in the temperature range 4–293 K, using a three-terminal capacitance dilatometer of recent design and construction. The linear thermal expansion measured is generally of the form predicted by a simple Debye model, with a room-temperature value of 1·06 × 10⁻⁵ K⁻¹. This value is consistent with the room-temperature value of the coefficient of volume expansion of 3·1 × 10⁻⁵ K⁻¹ used by previous authors, who obtained this value by extrapolation of early, limited low-temperature data.

At low temperatures (4–20 K), the thermal expansion deviates from a T ³ law in a similar manner to the reported behaviour of the low-temperature specific heat of a-As. The Grüneisen coefficient in this temperature range has been calculated to vary between 1 and 1·95.