X-ray study of the average structures of Cu2Se and Cu1.8S in the room temperature and the high temperature phases

Yamamoto, Kōji; Kashida, Shoji

doi:10.1016/0022-4596(91)90289-t

Cited by 132 publications

(106 citation statements)

References 16 publications

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“…Green energy is now getting more attention because of environmental concerns and global warming issues associated with consumption of fossil fuels. One of the major issues associated with low efficiency of different ARTICLES SCIENCE CHINA Materials conduction mechanism, along with a unique phase transition from low temperature α to high temperature β phase near 400 K [13]. The α phase can be crystallized into cubic, monoclinic, orthorhombic or tetrahedral structure, while the β phase always exhibits cubic phase in which Cu atoms are distributed on tetrahedral sites due to high mobility and immobile Se atoms are located on face-centered cubic site which results in superionic behavior [14].…”

Section: Introductionmentioning

confidence: 99%

Pronounced effect of ZnTe nanoinclusions on thermoelectric properties of Cu2−x Se chalcogenides

et al. 2016

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(Mahmood N)) energy systems is the loss of energy such as heat production. However, thermoelectric materials have the ability to convert waste heat into electrical energy without making the system complex which makes these materials noiseless and environment friendly. The efficiency of thermoelectric materials can be characterized by the dimensionless figure of merit (zT = S 2 σT/ĸ), where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature and ĸ is the total thermal conductivity comprised of lattice thermal (ĸ l ) and electronic thermal (ĸ e ) conductivities. Hence, the efficiency of a thermoelectric material can be enhanced by increasing the power factor and decreasing the total thermal. As S and k are interconnected to each other, the only possible way to enhance the efficiency of thermoelectric materials is to break the linkage between electronic and thermal transport properties. It has been experimentally proved that by reducing the particle size from their mean free path, thermal conductivity can be suppressed by breaking the linkage between electrical and thermal transport properties [1]. Meanwhile, the thermoelectric efficiency has also been enhanced by using various techniques such as growth of nanowires [2,3], nanocomposites [1,4−6], superlattices [7] and thin films [8]. Bulk nanocomposites has also been reported to reduce thermal conductivity without affecting the electronic transport [5]. Presently, copper chalcogenides are getting more attention due to their simple chemical formula but complex crystal structures [9−12]. Among the other copper chalcogenides, copper selenide has been investigated as a potential thermoelectric material due to the mixed electronic and ionic ABSTRACT Metal chalcogenides especially Cu2−xSe has gained much attention in thermoelectric community due to its complex crystal structure and superionic behavior. Here, we report a facile method to improve the thermoelectric efficiency by introducing ZnTe nanoinclusions into the matrix of Cu2−xSe. As a result, a substantial improvement of 32% in electrical conductivity of Cu2−xSe-ZnTe composite is observed. The increase in electrical conductivity is at the expense of Seebeck coefficient, which slightly decreases the power factor of the composite samples than that of pure Cu2−xSe. Furthermore, the introduction of secondary phase facilitates in declining the total thermal conductivity of Cu2−xSe-ZnTe composite up to 34% by suppressing the lattice thermal contributions. Thus, the moderate power factor and lower thermal conductivity values result in an improved figure of merit (zT) value of ~0.40 in mid-range temperature (750 K) for Cu2−xSe-ZnTe composite with 10 wt.% of ZnTe, which is about 40% higher than that of its pure counterpart. Hence, it is believed that the incorporation of ZnTe nanoinclusions in the matrix of Cu2−xSe may be an important route to improve the thermoelectric properties of Cu2−xSe based compounds.

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Section: Introductionmentioning

confidence: 99%

Pronounced effect of ZnTe nanoinclusions on thermoelectric properties of Cu2−x Se chalcogenides

et al. 2016

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“…Motivated by these facts, β-phase Cu 2 Se crystalized in layered cubic structure, as shown in Figure 1a and b, could very likely have a low thermal conductivity and good thermoelectric properties since these polycrystals have monoatomic Se layers acting as ordered lamella, and Cu atoms randomly distribute at several lattice sites as the disordered lamella (Fig. 1a, b), if one views along the (111) plane directions [16]. In this paper, we show that a ZT of about 1.6 at 700 °C could be obtained in β-phase Cu 2 Se polycrystals with such structure features.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2012

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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. §

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“…During the last two decades, less expensive methods, like chemical and electrochemical conversion, precipitation, ion displacement, electrodeposition and low temperature dip type for the preparation of copper selenide and their characterization have been reported by several authors [1, 2,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. CBD is a method of growing thin film of certain materials on a substrate immersed in an aqueous bath containing appropriate reagents at temperatures ranging from room temperature to 373K.…”

Section: Introductionmentioning

confidence: 99%

“…The techniques adopted for deposition of this metal chalcogenide vary from reaction of metallic copper with selenium dissolved in a benzene medium [1] or an aqueous medium [2], flash evaporation [3], vacuum evaporation [4][5][6][7], melting of Cu and Se [8,9], and electrodeposition [10], to the simplest method of chemical bath deposition (CBD) [11][12][13][14][15][16][17][18][19][20][21][22]. Copper selenide exists in widely differing crystallographic structures depending on the method of preparation even at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Structural, electrical and optical properties of copper selenide thin films deposited by chemical bath deposition technique

Al-Mamun

Islam

Bhuiyan

2005

J Mater Sci: Mater Electron

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A low cost chemical bath deposition (CBD) technique has been used for the preparation of Cu 2-x Se thin films on glass substrates. Structural, electrical and optical properties of these films were investigated. X-ray diffraction (XRD) study of the Cu 2-x Se films annealed at 523K suggests a cubic structure with a lattice constant of 5.697Å. Chemical composition was investigated by X-ray photoelectron spectroscopy (XPS). It reveals that absorbed oxygen in the film decreases remarkably on annealing above 423K. The Cu/Se ratio was observed to be the same in as-deposited and annealed films. Both as-deposited and annealed films show very low resistivity in the range of (0.

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X-ray study of the average structures of Cu2Se and Cu1.8S in the room temperature and the high temperature phases

Cited by 132 publications

References 16 publications

Pronounced effect of ZnTe nanoinclusions on thermoelectric properties of Cu2−x Se chalcogenides

Pronounced effect of ZnTe nanoinclusions on thermoelectric properties of Cu2−x Se chalcogenides

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

Structural, electrical and optical properties of copper selenide thin films deposited by chemical bath deposition technique

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