Thermoelectric properties of copper selenide with ordered selenium layer and disordered copper layer

Abstract

Thermoelectric figure of merit (ZT) of ~1.6 at 700 °C is achieved in β-phase copper selenide . A λ-shaped specific heat peak indicates a phase transition from cubic β-phase to tetragonal α-phase at around 140 °C upon cooling and vice versa. An abnormal decrease in specific heat with increasing temperature was also observed due to the increased random motion of disordered Cu atoms.These features indicate that β-phase Cu 2 Se could be potentially an interesting thermoelectric material, competing with other conventional thermoelectric materials. §

Promising bulk nanostructured Cu2Se thermoelectrics via high throughput and rapid chemical synthesis

“…Nano and micro grain sizes and their distribution in the structure have a strong influence on the TE properties of the compound. K. Comparing the electrical conductivity with the values reported by Gahtori et al [15] and Yu et al [6] , some 15% (≈1000 S/cm) and almost 75% (≈725 S/cm) enhancements are observed at RT, respectively. This might be due to the percolated network of large (micron-sized) grains in the Cu 2 Se_nl compound.…”

“…Copper selenide structures have previously been used in photovoltaic cells and devices [2,3] and are being considered even in biological systems [4] . This renewed interest can be attributed to the low thermal conductivity of the material as well as to its phase changing nature, which is an interesting aspect of the material [5][6][7][8][9][10] . The constituent elements are abundant in nature, and are considered as more benign in comparison to many other TE structures, especially those containing Pb, Sb, As, etc.…”

“…Additionally, Cu 2-x Se exhibits an electronic-ionic conduction mechanism that has a great influence on different properties, such as the specific heat capacity (c p ), which approaches the theoretical limit of solid crystalline materials compared to liquids [5,6,8,11,12] . Different methods have been used for the fabrication of these materials, including melt alloying [2,5,7,8,12,13] , 3 mechanical alloying (ball milling) [6,14,15] , self-propagating high-temperature synthesis (SHS) [10] , and chemical routes using aqueous solutions either directly [9,16,17] or solvothermally precipitated using autoclave [18] or organometallic precursors [4,19] .…”

“…Different methods have been used for the fabrication of these materials, including melt alloying [2,5,7,8,12,13] , 3 mechanical alloying (ball milling) [6,14,15] , self-propagating high-temperature synthesis (SHS) [10] , and chemical routes using aqueous solutions either directly [9,16,17] or solvothermally precipitated using autoclave [18] or organometallic precursors [4,19] . Some of these processes require high temperatures (above 1000 K), long processing times, which consumes a lot of energy, or inert atmosphere glove boxes for powder handling, which are expensive.…”

Promising Thermoelectric Bulk Materials with 2D Structures

“…The drastic off center behavior indicates inten sive scattering at the Cu site, similar to a rattling atom. This is attributed to the suppression of ionic conduction, as investi gated in the Cu 2 Se system, [124][125][126] which leads to weak bonding between Cu and Se, due to the lack of diffusion path for Cu + ions in the [Cu 2 Se 2 ] 2− layers. Via a projected Grüneisen parame ters calculation, the contributions of Cu and Se are highlighted, rather than the Bi site, as once thought.…”