Low hysteresis and large room temperature magnetocaloric effect of Gd5Si2.05−xGe1.95−xNi2x (2x = 0.08, 0.1) alloys

Abstract

Gd5Si2.05−xGe1.95−xNi2x (2x = 0.08, 0.1) alloys were prepared by arc melting followed by annealing at 1273 K for 96 h. Mixed monoclinic Gd5Si2Ge2-type phase, orthorhombic Gd5Si4-type phase, and a small amount of Gd5Si3-type phase were obtained in these alloys. Gd5Si2.01Ge1.91Ni0.08 alloy undergoes a second-order transition (TC) around 300 K, whereas Gd5Si2Ge1.9Ni0.1 alloy exhibits two transitions including a first-order transition (TCІІ) at ∼295 K and second-order transition (TCІ) at ∼301 K. Ni substitution can effectively reduce the thermal hysteresis and magnetic hysteresis while maintaining large magnetic entropy change. The maximum magnetic entropy changes (|ΔSMmax|) of Gd5Si2.05−xGe1.95−xNi2x alloys with 2x = 0.08 and 0.1 are 4.4 and 5.0 J kg−1 K−1, respectively, for 0–2 T, and are 8.0 and 9.1 J kg−1 K−1, respectively, for 0–5 T. Low hysteresis performance and relatively large magnetic entropy change make these alloys favorable for magnetic refrigeration applications.

A Contrastive Analysis of Gd5(SixGe1-x) Based Alloys Useful for Magnetic Refrigeration

“…The MCE results from changes in the magnetic order of materials, with the most optimum MCE near the was found to increase when Fe was substituted for Ge but it rather decreased rapidly when it was substituted for Si as can be seen in Table 3 [30]. However, in the case of doping the same amount of either Ni or Bi had a negligible effect on the magnetocaloric properties [26,27]. Experimental results have shown that a small amount of Sn doping enhances its MCE properties as well as increase its T C [15] but either leads to increase in hysteresis loss or has negligible effect on its reduction [15,27,31].…”

“…A lot of effort have gone in hysteresis loss reduction through doping of Fe, Cu, Co, Ga, Mn, Ni, Nb or Al for Si/Ge in Gd 5 (Si x Ge 1-x ) 4 compound between 270 K and 300 K as can be seen in Table 3. Two side effects have been observed: (1) Broadening of MCE peak on account of suppression of the reversible field-induced first-order monoclinic-to-orthorhombic phase transition, and (2) Shifting of MCE peak position between 270 K and 300 K temperature range [15,19,[25][26][27].…”

Structure, magnetic properties and giant magnetocaloric effect of Tb4Gd1Si2.035Ge1.935Mn0.03 alloy

“…The ÀDS peak M value of Tb 5 Si 1.95 Ge 1.95 Mn 0.1 is about 20.84 J/ kg around 123 K for a magnetic field change of 0e5 T. In our previous work [18], the results showed that Gd 5 Si 2.05Àx Ge 1.95Àx Ni 2x alloys with 2x ¼ 0.1 obtained a nearly single 5-2-2 phase, but when decreasing Ni content to 2x ¼ 0.08, the formation of 5-2-2 phase was suppressed, thus the hysteresis effect can be reduced evidently. Likewise, Shull's work [17] showed the Gd 5 Si 2 Ge 2 alloy remained the single phase with monoclinic 5-2-2 type when Bi and Sn replacing Ge, and the doping had little effect on hysteresis effect.…”

Large Magnetocaloric Effect with a Wide Working Temperature Span in the Intermetallic Compound Nd4PtMg

“…Many are concentrating on MCE technology because of its higher energy efficiency and lower environmental hazard (eco-friendly) concern when compared to the conventional gas compression method. Magnetic materials with large magneto-caloric effect have been studied in a detailed fashion in both experimental and theoretical methods for the better understanding the properties of the materials [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. MCE near to the room temperature is used for industrial refrigeration [17], which can reduce the greenhouse gases.…”