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Title: The magnetic phase transition in Mn{sub 1.1}Fe{sub 0.9}P{sub 1−x}Ge{sub x} magnetocaloric alloys

Mn-Fe-P-Ge alloys are promising, low cost, high performance candidates for magnetic cooling applications based on the magnetocaloric effect. These alloys undergo a magnetic phase transition which induces a large entropy change (ΔS). Experimental and modeling studies were conducted to study this transition for varying Ge content. Landau theory and the Bean-Rodbell model were applied to Mn{sub 1.1}Fe{sub 0.9}P{sub 1−x}Ge{sub x} (x = 0.26, 0.3, and 0.32) melt spun ribbons to model the phase transition and the associated entropy change. The critical behavior of these alloys was studied. The critical composition range at which the cross over from first order to second order magnetic transition occurs was determined. The calculated thermodynamic values and critical temperatures were in good agreement with our experimental results. A high maximum entropy change (ΔS) of ∼44.9 J kg{sup −1} K{sup −1} was observed in Mn{sub 1.1}Fe{sub 0.9}P{sub 0.74}Ge{sub 0.26} in a 5 T applied magnetic field. The results suggest that Mn-Fe-P-Ge alloys are very attractive materials for near room temperature magnetic cooling.
Authors:
;  [1]
  1. School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore 639798 (Singapore)
Publication Date:
OSTI Identifier:
22413091
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 6; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ADIABATIC DEMAGNETIZATION; CRITICAL TEMPERATURE; ENTROPY; GERMANIUM ADDITIONS; IRON ALLOYS; MAGNETIC FIELDS; MAGNETIC MATERIALS; MAGNETIC PROPERTIES; MANGANESE ALLOYS; PERFORMANCE; PHASE TRANSFORMATIONS; PHOSPHORUS ADDITIONS; TEMPERATURE RANGE 0273-0400 K