Low temperature specific heat of lutetium trihydride

The low temperature heat capacity measurements for the LuH2.84 trihydride sample are reported. The analysis of Cp(T) was performed on the basis of the Debye and Einstein approximations. The characteristic temperatures: ΘD = 227 K for Lu atoms, ΘEI=97 K, ΘEII=886 K and ΘEIII=1380 K for hydrogen sublattice are estimated. The analysis of the Cp(T) results at the lowest temperatures indicates that the so-called model V   of modified P3¯c1 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 Cp values of LuH2.84 trihydride are given.