Increase in the Thermoelectric Efficiency of the Disordered Phase of Layered Antiferromagnetic CuCrS2

Abstract

The thermoelectric figure of merit (ZT) of the layered antiferromagnetic compound CuCrS 2 is further improved with increase in the Cr-vacancy disorder on sintering above 900°C. X-ray photoelectron spectroscopy and x-ray diffraction refinement results for different samples show that the chromium atoms are transferred from the filled layers to the vacant sites between the layers. This atomic disorder increases the electrical conductivity (r) due to self-doping of the charge carriers and reduces thermal conductivity (j) due to increase in phonon scattering. The Seebeck coefficient (S) is p-type and remains nearly temperature independent with values between 150 lV/K and 450 lV/K due to electronic doping in different samples.

Effect of the Order-Disorder Transition on the Electronic Structure and Physical Properties of Layered CuCrS2

“…Copper-chromium disulfide CuCrS 2 is considered to be a promising functional material for electronic devices. Undoped copper-chromium disulfide and CuCrS 2 based solid solutions exhibit a wide range of physical properties such as thermoelectricity [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ], ionic conductivity [ 17 , 18 , 19 , 20 , 21 ] and various magnetic properties [ 22 , 23 , 24 ]. Thanks to the combination of ionic conductivity and thermoelectric properties (the Seebeck coefficient, electric and thermal conductivities, ZT) demonstrated by CuCrS 2 and similar layered transition metal dichalcogenides MCrX 2 (M = Cu, Ag; X = S, Se), these compounds can be considered phonon glasses.…”

“…Both Se/Te-based systems materials were reported to have a promising ZT values of ~1.5. However, CuCS 2 was also reported to have high ZT values of ~2 [ 14 ]. Thus, this fact makes it promising to study the thermoelectric properties of CuCrS 2 and CuCrS 2 -based materials.…”

CuCrSe2 Ternary Chromium Chalcogenide: Facile Fabrication, Doping and Thermoelectric Properties

“…In addition, the synthesis of the compound is also a concern. Currently it is mainly prepared by vacuum melting, which needs to be held at 1173 K for 72 h and then a further annealing at somewhat lower temperature for a long time is also indispensible to eliminate impurities (e.g., CuCr 2 Se 4 ) . The whole process is heavily energy‐consuming and quite time‐taking.…”

“…Currently it is mainly prepared by vacuum melting, which needs to be held at 1173 K for 72 h and then a further annealing at somewhat lower temperature for a long time is also indispensible to eliminate impurities (e.g., CuCr 2 Se 4 ). 13,14,16 The whole process is heavily energyconsuming and quite time-taking. As is known, mechanical alloying (MA) is a very powerful powder method for materials synthesizing, and many materials with special structure, like some intermetallic compounds, supersaturated solid solution and amorphous alloys, which are difficult to be prepared by conventional methods, have already been fabricated by mechanical alloying.…”

Ordered-Defect Sulfides as Thermoelectric Materials

“…However, to the best of our knowledge, the thermal conductivity of this phase has not been determined. The thermoelectric properties of p-type CuCrS 2 have been the subject of considerable recent interest following the report of a figure of merit as high as 2.0 at room temperature [11,12]. The performance of this material appears to be sensitive to the thermal history of the sample.…”