The low temperature thermal expansion and Gruneisen functions of tellurium

The coefficients of thermal expansion parallel and perpendicular to the c axis ( alpha /sub /// and alpha perpendicular to ) have been measured for tellurium over the temperature range 4 to 200 K. Throughout this temperature range alpha /sub /// is confirmed as being negative and alpha perpendicular to positive. The Gruneisen functions gamma /sub /// and gamma perpendicular to have been obtained and analysed. Accurate values for these functions for temperatures less than about 30 K are presented here for the first time: gamma perpendicular to has a broad shallow maximum centred near 30 K while gamma /sub /// is negative below about 18 K and has a sharp minimum centred near 8 K. The strain dependence of the moments of the frequency distribution gamma perpendicular to (n) and gamma /sub /// (n) have been derived for -3