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arXiv · 1505.02573

Influence of short time milling in R5(Si,Ge)4, R =Gd and Tb, magnetocaloric materials

A. L. Pires·J. H. Belo·J. Turcaud·G. N. P. Oliveira·J. P. Araújo·A. Berenov·L. F. Cohen·A. M. L. Lopes·A. M. Pereira
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Abstract

The effect of the short milling times on R5(Si,Ge)4 R =Gd, Tb magnetocaloric material properties was investigated. In particular, the effect of milling on atomic structure, particles size and morphology, magnetic, and magnetocaloric effect was studied. With short milling times (< 2.5h), a reduction of the Gd5Si1.3Ge2.7 and Tb5Si2Ge2 particles size was achieved down to approximately 3.5 DSm. For both compositions the main differences are a consequence of the milling effect on the coupling of the structural and magnetic transitions. In the Gd5Si1.3Ge2.7 case, a second-order phase transition emerges at high temperatures as a result of ball milling. Consequently, there is a decrease in the magnetocaloric effect of 35% after 150 minutes of milling. Interestingly, an opposite effect is observed in Tb5Si2Ge2 where a 23% increase of the magnetocaloric effect was achieved, driven by the enhancement of the coupling between magnetic and structural transitions arising from internal strain promoted by the milling process.

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A. L. Pires, J. H. Belo, J. Turcaud, G. N. P. Oliveira, J. P. Araújo, A. Berenov, L. F. Cohen, A. M. L. Lopes, A. M. Pereira. 2015-05-11. Influence of short time milling in R5(Si,Ge)4, R =Gd and Tb, magnetocaloric materials. https://arxiv.org/abs/1505.02573

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