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 thermoelectric Zn-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 degrees C and decomposes peritectically at about 360 degrees C. The high-temperature form of ZnSnSb2 adopts the Zn/Sn disordered cubic sphalerite-type structure. Electron microscopy investigations reveal that samples quenched from 350 degrees C already contain domains of the low-temperature form, which has the Zn/Sn ordered tetragonal chalcopyrite structure. The c/a ratio of the tetragonal structure is, within experimental errors, identical to the ideal value 2. This gives rise to intricate microtwinning in the low-temperature chalcopyrite form of ZnSnSb2 as obtained in samples quenched from 250 degrees C. First principles electronic structure calculations demonstrate that the tetragonal low-temperature form of ZnSnSb2 has a narrow band gap of about 0.2 eV. 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-Sb frameworks. However, the thermopower of ZnSnSb2 is rather low with room-temperature values ranging from 10 to 30,mu V/K.
Place, publisher, year, edition, pages
2005. Vol. 17, no 24, 6080-6085 p.
brillouin-zone integrations, order-disorder transition, augmented-wave method, thermoelectric properties, phonon-glass, surfaces, metals, zn4sb3, znsnp2, zinc
IdentifiersURN: urn:nbn:se:kth:diva-15197DOI: 10.1021/cm0516053ISI: 000233507600028ScopusID: 2-s2.0-28944441921OAI: oai:DiVA.org:kth-15197DiVA: diva2:333238
QC 201005252010-08-052010-08-05Bibliographically approved