Magnetic, magnetocaloric, and magnetoelastic properties of LaFe11.57Si1.43Bx compounds

Abstract

We have studied the magnetic, magnetocaloric, and magnetoelastic properties of LaFe 11.57 Si 1.43 B x compounds in the concentration interval 0 Ͻ x Յ 1.64 using magnetization and strain gauge techniques. The crystal cell parameters and Curie temperatures were found to increase linearly with increasing B concentrations up to ϳ0.1% and 9%, respectively. A positive magnetovolume anomaly of about 0.22% was observed in the vicinity of T C . The magnetovolume coupling constant was estimated to be approximately 3 ϫ 10 −3 ͓ B / Fe atom͔ −2 . Magnetic entropy changes at T C slightly depended on B concentration. A hysteresis loss of about ten times smaller relative to the base compound ͑x =0͒ was observed for x = 1.64. Therefore it was shown that the characteristics of the magnetocaloric effect of LaFe 11.57 Si 1.43 can be adjusted by a change in B concentration in the LaFe 11.57 Si 1.43 B x system. The relative importance of the variation in the volume of crystal cell and electron concentration on T C was discussed.

Phase, structural, and magnetocaloric properties of high temperature annealed LaFe11.6Si1.4BX

“…Those indicate that B atoms can dissolve into the lattice or substitute the matrix atoms of the compound to form solid solution, and the content of solid solution raises with the increase of B in LaFe 11.6 Si 1.4 B x compounds. But concerning with whether or not all B element can enter into crystal lattice interstice of 1:13 phase to form interstitial solid solution, our result is different to some previous result, which showed that B atoms can dissolve into the lattice or substitute other atoms to form interstitial solid solution and the range of solid solution is large [25,26], even to x = 1.64 in LaFe 11.57 Si 1.43 B x compounds, and indexed the diffraction peaks of about 2Â = 44.7 • and 2Â = 45 • as peaks of ␣-Fe phase. From Fig.…”

“…Hydrogen, nitrogen, carbon, and boron atoms, introduced as interstitial atoms, affect the magnetic properties by lattice expansion and hybridization [22][23][24][25]. It has been reported that boron has large content of dissolving in the crystal lattice of LaFe 13−x Si x to form interstitial solid solution, even up to 1.64 in LaFe 11.57 Si 1.43 B x compounds [26]. T C has been considerably increased in borides of LaFe 13−x Si x by B atoms without much affecting its interesting magnetocaloric properties, the magnetic hysteresis loss reduced almost to zero [25,26].…”

“…It has been reported that boron has large content of dissolving in the crystal lattice of LaFe 13−x Si x to form interstitial solid solution, even up to 1.64 in LaFe 11.57 Si 1.43 B x compounds [26]. T C has been considerably increased in borides of LaFe 13−x Si x by B atoms without much affecting its interesting magnetocaloric properties, the magnetic hysteresis loss reduced almost to zero [25,26]. In this paper, boron has been incorporated in LaFe 11.6 Si 1.4 by arc melting and then annealing at 1373 K (1.5 h) + 1523K(5 h).…”

Reduction in hysteresis losses and large magnetic entropy change in the B-doped La(Fe,Si)13 compounds

“…9 Very recently, the magnetocaloric properties of LaFe 11.57 Si 1.43 B x ͑0 Ͻ x Ͻ 1.64͒ compounds were studied by Pathak et al They observed that the hysteresis loss for the sample of x = 1.64 is much less than that of the sample of x=0. 10 Further investigations on hysteresis of La͑Fe, Si͒ 13 -based compounds are important from the practical viewpoint. In this paper, we report the effect of the substitution of B for Fe on ⌬S M and hysteretic losses in the La͑Fe, Si͒ 13 compounds.…”

“…It is found that the substitution of B for Fe leads to an increase in both a and T C for La͑Fe, Si͒ 13 compounds at constant Si concentration as shown in LaFe 11.57 Si 1.43 B x . 10 For the Fe-rich rare-earth ͑R͒ iron compounds, T C depends mainly on Fe-Fe direct exchange interactions. The exchange integral is affected by interatomic distance.…”