Cd Substitution in MxZn4−-xSb3: Effect on Thermal Stability, Crystal Structure, Phase Transitions, and Thermoelectric Performance

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• 作者：Birgitte L. Pedersen ; Hao Yin ; Henrik Birkedal ; Mats Nygren ; Bo B. Iversen
• 刊名：Chemistry of Materials
• 出版年：2010
• 出版时间：April 13, 2010
• 年：2010
• 卷：22
• 期：7
• 页码：2375-2383
• 全文大小：898K
• 年卷期：v.22,no.7(April 13, 2010)
• ISSN：1520-5002

文摘

The effects of Cd substitution in M_xZn_4−xSb₃ on the high-temperature thermal stability, low-temperature phase transitions and thermoelectric properties have been studied on three samples with a substitution degree of 0.1, 1, and 2 at % Cd (x = 0.004, 0.04, 0.08). The high-temperature thermal stability in atmospheric air of a 1% substituted sample is compared with an unsubstituted Zn₄Sb₃ sample. Multitemperature synchrotron powder diffraction data reveals that while only 42 wt % of the original Zn₄Sb₃ phase remains in the unsubstituted sample after three heating cycles to 625 K, 78 wt % is preserved in the Cd-substituted sample. Thus, Cd-substitution provides a significant improvement of the thermal stability of Zn₄Sb₃. Multitemperature synchrotron powder diffraction data measured between 90 and 300 K reveal that Cd substitution has a suppressing effect on the α′−α−β phase transitions. With increasing substitution, there is also a significant change in the individual Zn site occupancies. Differential scanning calorimetry shows an apparent correlation between Cd content and phase transition temperature. Thermoelectric properties have been measured from 2 to 400 K for all samples, and although some physical properties are significantly affected by doping, no immediate improvement of ZT was achieved.