Enhanced Magnetocaloric Effects in R3(Ga1-xFex)5O12 (R=Gd, Dy, Ho; 0
Virgil Provenzano, J Li, T T. King, E R. Canavan, P Shirron, M J. DiPirro, Robert D. Shull
A series of R3(Ga1-xFex)5O12 (R=Gd, Dy, Ho; 03(Ga0.5Fe0.5)5O12 compound, which was reported in 1992 with possessing enhanced magnetocaloric effects, may be achieved by equilibrating at 1200 degrees C for 15 h, rather than at 900 degrees C for 15 h as it was done in the earlier studies. Magnetometry measurements showed that when Gd was substituted either by Dy or Ho, the material was superparamagnetic, possessing fine magnetic clusters resulting in enhanced magnetocaloric effects (DSm) with respect to the basic paramagnetic garnet (i.e., x=0). In addition, with variation in x, the optimal DSm was measured for the x=0.5 compound, similar to that found for the Gd-containing garnet nanocomposites. The optimal DSm values for the Ho- and Dy-containing compounds, respectively, were found to be about the same or smaller than that for the optimal Gd-containing nanocomposite Gd3(Ga0.5Fe0.5)5O12, despite the increased total angular moment. We interpret these results as indicating a reduction in the interaction strength between the rare-earth elements and the Fe as the Gd is replaced by Dy or Ho, and that Dy reduces this interaction strength faster than does Ho.
Journal of Magnetism and Magnetic Materials
magnetic refrigerants, magnetocaloric effect, nanocomposites, superparamagnetic, x-ray diffraction
, Li, J.
, King, T.
, Canavan, E.
, Shirron, P.
, DiPirro, M.
and Shull, R.
Enhanced Magnetocaloric Effects in R<sub>3</sub>(Ga<sub>1-x</sub>Fe<sub>x</sub>)<sub>5</sub>O<sub>12</sub> (R=Gd, Dy, Ho; 0<x<1) Nanocomposites, Journal of Magnetism and Magnetic Materials
(Accessed December 5, 2023)