Low temperature specific heat of lutetium trihydride

Abstract The low temperature heat capacity measurements for the LuH 2.84 trihydride sample are reported. The analysis of C p ( T ) was performed on the basis of the Debye and Einstein approximations. The characteristic temperatures: Θ D  = 227 K for Lu atoms, Θ E I = 97 K , Θ E I I = 886 K and Θ E I I I = 1380 K for hydrogen sublattice are estimated. The analysis of the C p ( T ) results at the lowest temperatures indicates that the so-called model V of modified P 3 ¯ c 1 crystal lattice symmetry seems to be the best approximation for the crystallographic unit cell of lutetium trihydride. It was found that no conduction electrons contributed to the specific heat. The reported experimental results can be used as reference data for the lattice contribution in the specific heat of all the heavy rare earth trihydride phases. The polynomials function to fit the measured C p values of LuH 2.84 trihydride are given.