type: Hooke

references:
  - J.R. Neighbours and G.A. Alers,
    Physical Review 111:707-712, 1958,
    https://doi.org/10.1103/PhysRev.111.707,
    fit to Tab. I (T_min=100K, T_max=300K)
  - Y.A. Chang and L. Himmel,
    Journal of Applied Physics 37:3567-3572, 1966,
    https://doi.org/10.1063/1.1708903,
    fit to Tab. II (T_min=300K, T_max=800K)

C_11: 124.1e+9
C_11,T: -3.148e+7
C_11,T^2: -6.594e+3

C_12: 93.7e+9
C_12,T: -1.657e+7
C_12,T^2: -4.220e+3

C_44: 46.4e+9
C_44,T: -1.775e+7
C_44,T^2: -1.973e+3

T_ref: 293.15