The thermal expansion of antimony and bismuth at low temperatures

Results of measurements of the linear thermal expansion of single-crystal rods of pure antimony and bismuth over the temperature range 200 °K to 8 °K, and 200 °K to 4·5 °K respectively, made using an optical lever dilatometer, are discussed. The principal linear expansion coefficients α perpendicular and α parallel in the directions perpendicular and parallel to the trigonal axis are tabulated and shown graphically as functions of temperature. For both materials α perpensicular is considerably less than α parallel , with antimony showing the greater anisotropy. α perpendicular for antimony is negative below 20 °K, passing through a minimum at 14·8 °K. Calculated values of the Grüneisen parameters, γ perpendicular and γ parallel , corresponding to α perpendicular and α parallel are tabulated together with estimates of the high-temperature limiting values of γ perpendicular and γ parallel .