First-principles calculations to investigate strong half-metallic ferromagnetic and thermoelectric sensibility of LiCrX (X = S, Se, and Te) alloys

Abstract

The electronic, elastic, and thermoelectric behaviors of the half-Heusler LiCrX (X = S, Se, and Te) compounds in the Type I phase are investigated. These three kinds of alloys have minimum energies of type I, rather than types II and III. As a result, Li, Cr, and X (X = S, Se, Te) atoms prefer the positions (0.25, 0.25, 0.25), (0.75, 0.75, 0.75), and (0, 0, 0) respectively. LiCrSe and LiCrTe are true half-metal ferromagnetic compounds with a spin polarization of 100 %, whereas LiCrS is a false half metal alloy. The mBJ-GGA potential technique is also used for calculating electronic, magnetic, and thermoelectric features. The predicted total magnetic moment of LiCrSe and LiCrTe alloys is 5 µB per formula unit, the majority of which is contributed by Cr. So, LiCrSe and LiCrTe alloys could be suitable for spintronic applications. The elastic properties of LiCrS, LiCrSe, and LiCrTe alloys in Type I phase are analysed and obey to the stability criteria, both LiCrS and LiCrSe are anisotropic, while LiCrTe is isotropic. The classical Boltzmann theory has been employed to investigate thermoelectric performance. The ZT of LiCrTe and LiCrSe can be increased to a comparatively high value (ZT = 0.9495 for LiCrSe and ZT = 0.9507 for LiCrTe) by optimizing the carrier concentration to n = 84.6 * 1021 cm−3 for LiCrSe and 67.4 * 1021 cm−3 for LiCrTe, respectively. In addition, decreasing the chemical potential of LiCrSe by 0.013 Ryd and LiCrTe by 0.025 Ryd, respectively, yields the same results for ZT. The ZT value of LiCrS exhibits a considerable value, and at 1000 K, it can be as high as 0.7091.