Crystal structure and physical properties of new Ca{sub 2}TGe{sub 3} (T = Pd and Pt) germanides

• Published in: Journal of solid state chemistry 2016-11, Vol.243
• Main Authors: Klimczuk, T., Xie, Weiwei, Winiarski, M.J., Kozioł, R., Litzbarski, L.S., Luo, Huixia, Cava, R.J.
• Format: Article
• Language: English
• Subjects: ALUMINIUM BORIDES; CALCIUM COMPOUNDS; CRYSTALS; ELECTRONIC STRUCTURE; GERMANIDES; HEXAGONAL LATTICES; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; LATTICE PARAMETERS; MATERIALS SCIENCE; PALLADIUM COMPOUNDS; PLATINUM COMPOUNDS; SPACE GROUPS; SPECIFIC HEAT; TEMPERATURE RANGE 0000-0013 K; TEMPERATURE RANGE 0273-0400 K
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/J.JSSC.2016.07.029

The crystallographic, electronic transport and thermal properties of Ca{sub 2}PdGe{sub 3} and Ca{sub 2}PtGe{sub 3} are reported. The compounds crystalize in an ordered variant of the AlB{sub 2} crystal structure, in space group P6/mmm, with the lattice parameters a = 8.4876(4) Å/8.4503(5) Å and c = 4.1911(3) Å/4.2302(3) Å for Ca{sub 2}PdGe{sub 3} and Ca{sub 2}PtGe{sub 3}, respectively. The resistivity data exhibit metallic behavior with residual-resistivity-ratios (RRR) of 13 for Ca{sub 2}PdGe{sub 3} and 6.5 for Ca{sub 2}PtGe{sub 3}. No superconducting transition is observed down to 0.4 K. Specific heat studies reveal similar values of the Debye temperatures and Sommerfeld coefficients: Θ{sub D} = 298 K, γ = 4.1 mJ mol{sup −1} K{sup −2} and Θ{sub D} = 305 K, γ = 3.2 mJ mol{sup −1} K{sup −2} for Ca{sub 2}PdGe{sub 3} and Ca{sub 2}PtGe{sub 3}, respectively. The low value of γ is in agreement with the electronic structure calculations.