Magnetic properties and magnetic-entropy change of MnFeP0.5As0.5−xSix(x=0–0.3) compounds

Abstract

The effects of Si substitution for As on the magnetic and magnetocaloric properties of MnFeP0.5As0.5−xSix compounds have been investigated. The Si-substituted compounds MnFeP0.5As0.5−xSix with x=0, 0.1, 0.2, and 0.3 have been prepared by high-energy ball milling and solid-state reaction. X-ray diffraction shows that all the MnFeP0.5As0.5−xSix compounds crystallize in the Fe2P-type structure. Magnetic measurements show that the compounds are ferromagnetic with a nonlinear dependence of TC on Si content. All compounds exhibit a field-induced first-order magnetic phase transition. The magnetic-entropy change is derived from the magnetization data by using the Maxwell relations. The maximum magnetic-entropy change observed in this system reaches about 32J∕kgK for a field change from 0to2T for x=0.2, at temperature around 294K.

Structure, magnetism, and magnetocaloric properties of MnFeP1−xSix compounds

“…The dependence of T C on the Si concentration is unusual, but in good agreement with previous results. 3,4 Ther XRD patterns of the samples with x ജ 0.64 show that the structure is no longer hexagonal Fe 2 P type. The crystal structure in this region has not yet fully been and is subject of future investigation.…”

“…However, the extremely strong dependence of the Curie temperature on the Ge concentration may present a problem as a small variation in the composition of the magnetic refrigerant may strongly alter its performance. 2 When partially replacing As by Si, 3 an enhancement of the magnetocaloric effect ͑MCE͒ is obtained while keeping a good tunability of the Curie temperature with the Si content. However, the thermal hysteresis is markedly increased, which is unfavorable for magnetic-cooling applications.…”

Microstructure, magnetic and magnetocaloric properties of Fe2–x Mn x P0.4Si0.6 alloys

“…After the discovery of the giant MCE in MnFe(P,As), many efforts have been devoted to replacing As by non-toxic components. The introduction of Si and Ge atoms into the lattice of MnFe(P,As) retains a giant MCE around room temperature, but an enhanced thermal hysteresis (ΔThys) is observed [11,12]. Recently, some meaningful studies have been done to reduce the ΔThys for MnFe(P,Ge) and MnFe(P,Si) compounds.…”

Tunable thermal hysteresis in MnFe(P,Ge) compounds

“…Although the introduction of Si and Ge atoms into the lattice of MnFeP 1−x As x retains a giant MCE around T room , an enhanced ⌬T hys was observed. [12][13][14][15] In this letter, we show that it is possible to reduce ⌬T hys of MnFe͑P,Ge͒ without losing the favorable magnetocaloric properties.…”

“…[12][13][14][15][16] The as-spun ribbons were subsequently quenched into water after annealing at 1100°C for 15 min. Powder x-ray diffraction ͑XRD͒ of the samples was made at T room in a Philips PW-1738 diffractometer with Cu K␣ radiation.…”