Weiqin Ao

Influence of Carbon on the Giant Magnetocaloric Effect of LaFe11.7Si1.3

The influences of carbon on phase formation, Curie temperature, and magnetic entropy change of the NaZn13-type LaFe11.7Si1.3 were investigated. Seven carbon-containing alloys, LaFe11.7Si1.3C(subscript x) with x=0, 0.03, 0.06, 0.10, 0.20, 0.30, and 0.50, respectively, were prepared for this investigation. Experimental results show that addition of a small amount of carbon in LaFe11.7Si1.3 is favorable for the formation of the NaZn13-type structure of LaFe11.7Si1.3C(subscript x). The lattice constant increases with C addition and x increases in the alloy because of the introduction of C as interstitial atoms. The Curie temperature of LaFe11.7Si1.3C(subscript x) increases from 194 K to 225 K as x increases from 0 to 0.5. Large magnetic entropy changes were observed in these carbon-containing alloys LaFe11.7Si1.3C(subscript x) because of their first-order structural/magnetic transition. The maximum magnetic entropy change of 27.5 J•kg^(-1)•K^(-1) at 202 K for the 0-1.56 T magnetic field change was observed in the alloy with x=0.06. The large magnetic-entropy changes corresponding to low magnetic field change, and the low cost of the material of LaFe11.7Si1.3C(subscript x) makes it a promising candidate to be used as magnetic refrigerants in the corresponding temperature range.

Ternary compounds and isothermal section in Lu–Fe–Ga ternary system at 773 K

The isothermal section of the Lu–Fe–Ga ternary system at 773u2009K was investigated and constructed based on X-ray powder diffraction analysis. Thirteen binary compounds, Lu2Fe17, Lu6Fe23, LuFe2, LuGa3, LuGa2, Lu3Ga5, LuGa, Lu3Ga2, Lu5Ga3, Fe3Ga, Fe6Ga5, Fe3Ga4, FeGa3, nine ternary solid solutions, T1-LuFe2–1.43Ga0–0.57, T2-LuFe1.34–0.92Ga0.68–1.08, T3-LuFe0.52–0.26Ga1.48–1.74, T5-LuFe2.04–1.72Ga0.96–1.28, T6-Lu6Fe23–21.4Ga0–1.6, T7-Lu2Fe17–14.5Ga0–3.5, T8-Lu2Fe12.9–8.1Ga4.1–8.9, T9-LuFe6.8–5.5Ga5.2–6.5, T10-LuFe5.2–4.5Ga6.8–7.5, and two ternary compounds, T4-LuFe2.35Ga0.65 and T11-Lu2FeGa8 have been confirmed. The structures of the five new ternary compounds or solid solution T2, T3, T4, T5 and T8 are determined by Rietveld refinement method.