The low expansion characteristics along c appear to be controlled by the linkages between the (CuS 3 + BiS 2) sheets perpendicular to c being relatively inflexible. The Debye-Waller factor for the first shell of S atoms surrounding Cu in end member CuSbS 2 tends to be slightly smaller than for the intermediate solid solutions, suggesting that the tetrahedral Cu environments in the intermediate composition samples is somewhat more disordered than in the end-member. The local structure and co-ordination of Cu in the samples were studied by EXAFS analysis of the Cu- K edge but no significant variation occurs in the local Cu environment. With the addition of 10 CuSbS2 to CuBiS2, the decomposition temperature increases and the. No evidence of this decomposition was observed when the amount of the CuSbS 2 component was >30%. Published online by Cambridge University Press: 05 July 2018. With the addition of 10% CuSbS 2 to CuBiS 2, the decomposition temperature increases and the endothermic peak is broadened but the energy remains essentially the same (2.53 kJ/mol.). DSC experiments on CuBiS 2 show an endothermic heat effect (2.45 kJ/mol.) at 472☌ due to the breakdown reaction to Cu 3BiS 3 (wittichenite) plus Bi 2S 3 (bismuthinite). All members of the series are orthorhombic (space group Pnma) and show smoothly increasing a and b cell parameters with substitution of Bi for Sb the c cell parameter increases up to 50% CuBiS 2 substitution and then becomes constant. Seven compositions with the general formula Cu(Sb xBi 1– x)S 2 have been synthesized using dry methods at 310☌. Sulphosalts in the system CuSbS 2-CuBiS 2 (chalcostibite-emplectite) form a complete solid solution series.
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