| Autor: |
Chetty, Raju, Prem Kumar D. S., Rogl, Gerda, Rogl, Peter, Bauer, Ernst, Michor, Herwig, Suwas, Satyam, Puchegger, Stephan, Giester, Gerald, Mallik, Ramesh Chandra |
| Zdroj: |
Physical Chemistry Chemical Physics (PCCP); 2015, Vol. 17 Issue 3, p1716-1727, 12p |
| Abstrakt: |
Tetrahedrite compounds Cu12-xMnxSb4S13 (0 ⩽ x ⩽ 1.8) were prepared by solid state synthesis. A detailed crystal structure analysis of Cu10.6Mn1.4Sb4S13 was performed by single crystal X-ray diffraction (XRD) at 100, 200 and 300 K confirming the noncentrosymmetric structure (space group I %43m) of a tetrahedrite. The large atomic displacement parameter of the Cu2 atoms was described by splitting the 12e site into a partially and randomly occupied 24g site (Cu22) in addition to the regular 12e site (Cu21), suggesting a mix of dynamic and static off-plane Cu2 atom disorder. Rietveld powder XRD pattern and electron probe microanalysis revealed that all the Mn substituted samples showed a single tetrahedrite phase. The electrical resistivity increased with increasing Mn due to substitution of Mn2+ at the Cu1+ site. The positive Seebeck coefficient for all samples indicates that the dominant carriers are holes. Even though the thermal conductivity decreased as a function of increasing Mn, the thermoelectric figure of merit ZT decreased, because the decrease of the power factor is stronger than the decrease of the thermal conductivity. The maximum ZT = 0.76 at 623 K is obtained for Cu12Sb4S13. The coefficient of thermal expansion 13.5 ± 0.1 × 10-6 K-1 is obtained in the temperature range from 460 K to 670 K for Cu10.2Mn1.8Sb4S13. The Debye temperature, ΘD = 244 K for Cu10.2Mn1.8Sb4S13, was estimated from an evaluation of the elastic properties. The effective paramagnetic moment 7.45 mB/f.u. for Cu10.2Mn1.8Sb4S13 is fairly consistent with a high spin 3d5 ground state of Mn. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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