Temperature dependence of the orthorhombic asymmetry of gallium metal

Precision strain-gauge measurements of the basal-plane lattice asymmetry (a-b)/[(a + b)/2] in gallium metal have been made in the temperature range 190 K < T< 300 K. When analyzed in conjunction with previously published data these results indicate that the asymmetry is positive from the melting point, T_M = 303 K, down to at least 2 K. The asymmetry reaches a limiting value of 5750 × 10^-6 at low temperatures and is decreasing rapidly toward zero near T_M. The extrapolated `tetragonality' temperature is T* ~ 354 K.