Characterization of quaternary Heusler alloys CoFeYGe ( Y  = Ti, Cr) with respect to structural, electronic, magnetic, mechanical, and thermoelectric features

Abstract

The electronic, magnetic, elastic, and thermoelectric properties of CoFeYGe (Y = Ti, Cr) quaternary Heusler compounds are studied using DFT simulations. Our calculations show that both CoFeYGe (Y = Ti, Cr) alloys have a Type-I atomic configuration. CoFeCrGe and CoFeTiGe compounds with band gaps of 0.640 eV and 0.489 eV, respectively, were found to display half-metallic behavior in the minority spin channels. The total magnetic moment of CoFeCrGe was 3.00 μ B , while CoFeTiGe's was 1.00 μ B . CoFeTiGe and CoFeCrGe are both mechanically stable in the Y-Type-I structure. The surface of E is entirely distorted, demonstrating substantial anisotropy for two compounds. They have a higher anisotropic Young's modulus in the (XY), (XZ), and (YZ) planes. At 900 K, ZT is 0.31706 (0.45308) for CoFeTiGe (CoFeCrGe), corresponding to a carrier concentration of n 0 = 20.4581 Â 10 21 cm À3 (64.5856 Â 10 21 ) cm À3 . Two ways exist to enhance ZT values of CoFeTiGe and CoFeCrGe to 0.4032 and 0.64149, respectively: A charge carrier concentration of 17.392 Â 10 21 cm À3 for CoFeTiGe and 59.503 Â 10 21 cm À3 for CoFeCrGe is obtained. The second similar result is obtained by raising the chemical potential of CoFeTiGe and CoFeCrGe by 0.068 and 0.980 Ryd, respectively. To our knowledge, CoFeCrGe and CoFeTiGe exhibit exceptional spintronic and thermoelectric properties.

Electronic, Magnetic, and Elastic Features of Quaternary Heusler Alloys: FeVScSb and FeVYSb

“…Heusler alloys of both quaternary FeVScSb and FeVYSb form cubic crystals of the LiMgPdSn (Y‐type) phase (space group ). [ 48–52 ] This structure has three possible nonequivalent superstructures (YI, YII, and YIII) summarized in Table 1 . In both FeVScSb and FeVYSb Heuslers, the three possible nonequivalent atomic arrangements (YI, YII, and YIII) are shown in Figure 1 .…”

First-principles investigation of the electronics, optical, mechanical, thermodynamics and thermoelectric properties of Na based Quaternary Heusler alloys (QHAs) NaHfXGe (X = Co, Rh, Ir)

“…For the practical implementation of any compounds especially in the field of TE applications; machinable factor (µ m ), Frantsevich ratio (G/B), and melting temperature (T m ) played a key role [63]. The calculated µ m by employing equation (12) suggest that the QHAs being investigated exhibit an acceptable level of machinability with lower feed forces and mediocre lubricating properties. Also, from the high T m and low G/B ratio, one can conclude that these compounds could be the next future TE materials that can be utilized at high temperatures.…”

“…Through the surveyed literature, it was found that Heusler alloys (HA) were broadly divided into four components namely; direct full-HA that crystallizes in L2 1 structure, consisting of four inter-penetrating face centered cubic (FCC) lattices with space group-225 (Fm-3m), inverse full-HA crystallizes in C1 b type structure with space group-216 (F-43m), half-HA that belongs to C1 b type structure, consisting of three in-equivalent atoms forming inter-penetrating FCC sub-lattices, and Quaternary-HA (QHA) that fits in C1 b structure with four in-equivalent atoms [3,8,9]. Over the last few decades, the theoretical and the experimental insight into novel semi-conducting QHA for TE devices have attracted much attention as they fulfill all the requisites for the materials to be utilized in the TE devices such as mechanical and thermal stability, non-toxicity, availability and the cost-effectiveness [10][11][12][13][14][15][16][17]. Also, the ease of tuning electronic properties through the band gap engineering.…”