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Size effect-enhanced thermoelectric properties of nanoscale Cu2-xSe
摘要： As a promising thermoelectric material, copper selenides have attracted the interest of researchers owing to their low cost, abundance in earth, environmental friendliness, and low thermal conductivity. In this study, copper selenide (Cu2-xSe) powders with controllable sizes from nanoscale to mesoscale were obtained by a facile one-pot solvothermal method. After treatment with spark plasma sintering, the nanoscale Cu2-xSe pellets exhibited excellent thermoelectric properties such as sharply reduced thermal conductivity and enhanced Seebeck coefficient as well as a suppressed electrical conductivity. The figure of merit (ZT) of the nanoscale Cu2-xSe reached up to ~1.51 at 873 K, which is about 2.67 times higher than that of the meso-Cu2-xSe. This study confirms that thermoelectric properties can be enhanced by the size effect.
关键词： size effect,solvothermal method,thermoelectric property,Copper selenide,nanoscale
更新于2025-09-19 17:15:36
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Correlation between thermal-vibration-induced large displacement of Cu atoms and phase transition in Cu4SnS4: First-principles investigation
摘要： First-principles (FP) calculations and first-principles molecular dynamics (FPMD) simulations for Cu4SnS4 were performed to clarify the origin of the structural phase transition at 232 K between the high-temperature phase (HP) and low-temperature phase (LP), which leads to an experimentally measured drastic change in the transport properties of Cu4SnS4. The results of the FP and PFMD calculations indicated that, rather than being caused by the so-called freezing of soft modes, the key driving force behind the phase transition in Cu4SnS4 is a large-scale displacement of the Cu atoms located at particular sites due to thermal vibration. In fact, tetrahedrally coordinated CuS4 is stabilized by the effect of the thermal vibration of Cu atoms in the HP whereas CuS3, which is in a trigonal planar environment, is stabilized in the LP.
关键词： first-principles calculation,molecular dynamics simulation,thermoelectric property,electronic structure,phase transition
更新于2025-09-09 09:28:46