| Popis: |
Cu2Se, as a competitive thermoelectric material, has attracted much attention recently [1], mainly due to its large figure of merit (ZT), which is among highest for single crystalline compounds (1.5 at 1000K). This is predominantly associated with its superionic behavior in the high-temperature β-phase which also holds potential for applications in solid state batteries [2]. Although high temperature β-phase was extensively investigated, comprehensive insight of low temperature α phase is still lacking. It reflects the complexity of the structural and phase relations. The transition temperature from α phase to β phase considerably depend on x and mixed phase is between them [4]. We observe large temperature hysteresis probably related to the mechanism of this phase transition. The shape of hysteresis is strongly time dependent. Here we present detailed magnetotransport and thermoelectric properties of Cu2-xSe at low temperatures complemented with structural and magnetic studies. They will allow us to understand mechanism of order-disorder phase transition in Cu2-xSe subsystem which most probably lies behind wide temperature hysteresis observed in our results. References: [1] Liu, H. et al., Nature Materials 11. 422–425 (2012). [2] Hu L. et al., Nanomaterials 10. 302 (2020). [3] Eikeland, E. et al., Polymorph Materials, UCrJ4, 476 (2017). [4] Ogorelec, Z. et al., Journal of Materials Science 7. 967-969 (1972). |
