Crystal Structure and Magnetic Properties of La_0.8R_0.2(Fe_0.88Si_0.12)₁₃ (R = Sm and Tb) Compounds

Abstract

This study discusses the crystal structure and magnetic properties of the rare-earth doped La 0.8 R 0.2 (Fe 0.88 Si 0.12) 13 (with R = Sm, Tb) compounds. All the samples were prepared by using arc-melting technique in argon atmosphere and the obtained result shows that after heat treatment, the samples exhibited the NaZn 13-type cubic phase with a small amount of a secondary ¡-Fe phase. The magnetic properties and magnetic entropy change were determined by mean of the temperature and field dependence magnetizations. Besides the decrease in the lattice constants, there was also observed a significant increase of Curie temperature and magnetic entropy change ¹¦S M which reached a maximum of 4.5 J/kg K for La 0.8 Sm 0.2 (Fe 0.88 Si 0.12) 13 , corresponding to a relative cooling powers (RCP) of 102 J/kg for the sample.

Saturated Magnetization in Sm and Tb Doped La(Fe0.88Si0.12)13

“…The M(T) curves for the two cases of Sm and Tb-doped compounds were reported in ref. [5]. Here we show in Fig.…”

“…The alloys of nominal composition La0.8R0.2(Fe0.88Si0.12)13 (R = Sm, Tb) were fabricated by mean of arc-melting techique in Ar atmosphere at high vacuum (P = 10 5 Torr) as presented in ref. [5]. We note that a surplus of 2% of the precursors La and R metals were added as these metals are easily evaporated during melting process.…”

“…The structure analysis was reported in ref. [5], here we remeasured the magnetization by using the Superconducting Quantum Interference Device (SQUID) in a temperature range from 4 to 300 K and magnetic field up to 70 kOe, in the Japan Advanced Institute of Science and Technology (JAIST), Japan.…”

“…Magneto-caloric compounds are of great importance for application in modern environmental friendly gas-free cooling devices [1][2][3][4]. In our previous study [5], we reported on the magneto-caloric effects in 20% doped compounds La0.8R0.2(Fe0.88Si0.12)13 (R=Sm, Tb) where large values of RCP were observed. But due to technical limitation the values of magnetization were only achieved at applied field up to 15 kOe, so the achieved RCP were reported for H = 1.5 T, although there were signatures that the effective field variation may be significantly different.…”

“…As reported in ref. [5] the magnetization does not seem to be saturated at 15 kOe, and the practical RCP-s may be achieved at higher field variation than 15 kOe, which lower the chance for application. For this purpose, we redetect the saturated magnetization to shed light on to the application ability of Sm and Tb-doped compounds.…”