Composite Copper Chalcogenide Halides: Neutron Powder Diffraction of CuClCu2TeS3 and Electrical Properties of CuClCu2TeS3, (CuI)2Cu3SbS3, and (CuI)3Cu2TeS3

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The crystal structure of CuClCu2TeS3 was refined from TOF neutron powder diffraction data in order to verify the distribution of chlorine and sulfur. It is a novel derivative of the zincblende type with an ordered distribution both of the cations Cu+ and Te4+ and of the anions Cl− and S2−. The compound crystallizes in the rhombohedral system, space group R3m (No. 160) with a=7.3502(1) Å, c=10.3873(2) Å, V=485.99 Å3, and Z=3. The structure refinement converged to Rwp=0.039 and RBragg=0.032. From the neutron data it can be derived that there is no significant disorder of Cl and S atoms. Impedance spectroscopic measurements in the temperature range 140–280°C reveal that CuClCu2TeS3 is a semiconductor with an activation energy of 0.75 eV (T<200°C) and 1.25 eV (T>200°C), respectively. On the other hand (CuI)3Cu2TeS3 and (CuI)2Cu3SbS3 exhibit high copper ion conductivity with activation energies of 0.2 and 0.35 eV, respectively, but a negligible electronic conduction.