Beneficial effect of minor Al substitution on the magnetocaloric effect of Mn1−xAlxAs

Magnetocaloric effects and reduced thermal hysteresis in Si-doped MnAs compounds

“…2. Combined with our recent results on mechanical alloyed Al-substituted Mn 1−x Al x As powders where the Curie temperature of mechanical alloyed MnAs mother alloy is about 220 K measured in the heating process [10], the Curie temperature increases mono- tonically with increasing the Si content in MnAs 1−x Si x , which is in agreement with the XRD results above. It is worth noticing that the thermal hysteresis diminishes gradually from about 10 K in MnAs 0.97 Si 0.03 to nearly zero in MnAs 0.91 Si 0.09 .…”

“…It is worth noticing that the thermal hysteresis diminishes gradually from about 10 K in MnAs 0.97 Si 0.03 to nearly zero in MnAs 0.91 Si 0.09 . Compared with the thermal hysteresis in MnAs and other substituted alloys [5][6][7][8][9][10], it is concluded that the Si substitution is beneficial to decrease the thermal hysteresis, which is important to practical applications.…”

“…With increasing temperature, an inflexion can be observed on the magnetization curves, indicating a metamagnetic phase transition accompanied by a structural transition from paramagnetic MnP-type orthorhombic structure to ferromagnetic NiAs-type hexagonal structure. However, such increment on magnetization induced by the external field is not as obvious as that in other systems with large thermal hysteresis [5][6][7][8][9][10]. It is more analogous to a second-order phase transition, which is considered to relate closely with reduced thermal hysteresis.…”

Analysis of the Magnetocaloric Effect in Powder Samples Obtained by Ball Milling

“…Among RE-based materials Gd 5 Si 2 Ge 2 , [13,14] La(FeSi) 13 , [15][16][17][18] RE 2 Fe 17 intermetallics, [19,20] clathrates Eu 8 Ga 16 Ge 30 , [21] and amorphous alloys [13,14,22] can be found. Among TM-based systems Heusler alloys, [23][24][25] MnAs, [26][27][28][29] cFeNi, [30][31][32] and amorphous alloys [33][34][35][36][37] can be found. A general difference found in BM samples regarding their MCE with respect to that of bulk counterparts is a decrease of the DS M peak but a temperature broadening of the MCE response, which can lead to an enhancement of the refrigerant cooling power.…”

Comparative analysis of magnetic and caloric determinations of the magnetocaloric effect in Mn0.99Co0.01As

“…The MCE of MnAs and its derivatives, with slight substitutions of Fe, Cu, and Cr for Mn, or Si and Sb for As [3,[10][11][12][13][14][15][16], have been extensively studied using magnetization data. As a result of an incorrect application of the Maxwell relation, some fallacious conclusions saying that the MnAs-based compounds exhibit "huge" or "colossal" MCE (|ΔS T,max | ∼ 300 J/kg·K) were made [11,12,15]. In this paper, we report on a giant MCE at room temperature (∼295 K) in Mn 0.99 Co 0.01 As, using three different methods, i.e., isothermal magnetization, heat capacity, and direct measurements.…”