Sphalerite-Chalcopyrite Polymorphism in Semimetallic ZnSnSb2
2005 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 17, no 24, 6080-6085 p.Article in journal (Refereed) Published
We have investigated the system ZnSnSb2 in the course of our attempts to modify thermoelectricZn-Sb frameworks. ZnSnSb2 is only accessible when employing Sn as reactive flux in the synthesis.The material shows an order-disorder transition in the temperature interval between 225 and 240 °Cand decomposes peritectically at about 360 °C. The high-temperature form of ZnSnSb2 adopts the Zn/Sndisordered cubic sphalerite-type structure. Electron microscopy investigations reveal that samples quenchedfrom 350 °C already contain domains of the low-temperature form, which has the Zn/Sn ordered tetragonalchalcopyrite structure. The c/a ratio of the tetragonal structure is, within experimental errors, identical tothe ideal value 2. This gives rise to intricate microtwinning in the low-temperature chalcopyrite form ofZnSnSb2 as obtained in samples quenched from 250 °C. First principles electronic structure calculationsdemonstrate that the tetragonal low-temperature form of ZnSnSb2 has a narrow band gap of about 0.2eV. This is in agreement with the semimetallic behavior of the material found from resistivity measurement.The shape of the electronic density of states for ZnSnSb2 is similar to thermoelectric binary Zn-Sbframeworks. However, the thermopower of ZnSnSb2 is rather low with room-temperature values rangingfrom 10 to 30 íV/K.
Place, publisher, year, edition, pages
Washington, DC, 2005. Vol. 17, no 24, 6080-6085 p.
Research subject Inorganic Chemistry
IdentifiersURN: urn:nbn:se:su:diva-42921DOI: 10.1021/cm0516053OAI: oai:DiVA.org:su-42921DiVA: diva2:352224