Physical properties of {Ti,Zr,Hf} 2 Ni 2 Sn compounds

Physical properties, electrical resistivity (4.2-800 K), Seebeck coefficient (300-800 K), specific heat (2-110 K), Vickers hardness and elastic moduli (RT), have been defined for single-phase compounds with slightly nonstoichiometric compositions: Ti Ni Sn , Zr Ni Sn , and Hf Ni Sn . From X-ray single crystal and TEM analyses, Ti Ni Sn , ∼ 0.13(1), is isotypic with the U Pt Sn-type (space group 4 / , ternary ordered version of the Zr Al -type), also adopted by the homologous compounds with Zr and Hf. For all three polycrystalline compounds (relative densities >95%) the electrical resistivity of the samples is metallic-like with dominant scattering from static defects mainly conditioned by off-stoichiometry. Analyses of the specific heat curves and / reveal Sommerfeld coefficients of = 14.3(3) mJ mol K , = 10(1) mJ mol K , = 9.1(5) mJ mol K and low-temperature Debye-temperatures: LTD = 373(7)K, 357(14)K and 318(10)K. Einstein temperatures were in the range of 130-155 K. Rather low Seebeck coefficients (