Elastic constants of a Pd₈₅Pt₁₅ single crystal containing hydrogen

Sound velocity measurements carried out between 10 and 300 K in a Pd₈₅Pt₁₅ single crystal at 0 and 0.29 H contents for five different propagation modes, have shown that C', C₄₄ and C_T are strongly decreased by H loading (C_T=¹/₃(C₁₁-C₁₂+C₄₄)). Smaller relative changes are observed for longitudinal modes. The bulk modulus as well as the anisotropy factor turn out to be increased by H impurities. The Debye temperature as absolute zero is found to be 271+or-5 K for n=0 and 264+or-5 K for n=0.29.