Publication Date:
2016-09-03
Description:
The La-excess alloys La 1+δ (Fe 0.85 Si 0.15 ) 13 (δ = 0.06 and 0.09) exhibit large magnetocaloric effect which has been attributed to the occurrence of itinerant-electron metamagnetic transition near the Curie temperature T C . The maximum entropy change −Δ S m was shown to be from 4.5 to 11.5 J/kg K for the applied field variation Δ H from 20 to 70 kOe, respectively. The estimated relative cooling power for Δ H = 70 kOe was 418 J/kg. The alloys show a typical NaZn 13 -type cubic structure, featuring a doping-induced magnetovolume effect with the increase in T C . Under the applied pressure up to 2 GPa, the T C as deduced from resistance measurements decreased linearly, Δ T C = 113 (for δ = 0.06) and 111 K (for δ = 0.09), together with a corresponding decrease of resistivity, Δ ρ = 6.1 μΩ m at room temperature for both samples. At a low pressure, the effect of spontaneous magnetostriction on T C caused by applying the pressure appeared to have a similar magnitude to that of the negative magnetovolume effect caused by La-excess doping. In comparison with other stoichiometric La(Fe 1−x Si x ) 13 compounds, the pressure in our case was shown to have a smaller influence on T C .
Print ISSN:
0021-8979
Electronic ISSN:
1089-7550
Topics:
Physics
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