Abstract
In this thesis, a study was conducted on the magnetic phase transformation behavior and magnetocaloric effect (MCE) under a low magnetic field ranging from 0-1.5 T for the casted and annealed Gd5Si2Ge2alloys. The result shows that high-heat treatment significantly influences the structural and magnetocaloric properties of Gd5Si2Ge2alloy. High-heat treatment at 1573 K is beneficial to increasing Gd5Si2Ge2-type monoclinic structure which benefits the first-order transition. The MCE of annealed Gd5Si2Ge2alloy drastically increases and the highest value of SM~18.12 J/kg·K at 282 K upon H=1.5 T which is obviously larger than that of as-casted Gd5Si2Ge2( SM~5.03 kg·K at 276 K upon H=1.5 T). The giant magnetocaloric effect is obtained for Gd5Si2Ge2alloy by high-heat treatment.
Publisher
Trans Tech Publications, Ltd.