Phase relationships and structural, magnetic, and thermodynamic properties of alloys in the pseudobinary Er5Si4−Er5Ge4 system

作     者：A. O. Pecharsky K. A. Gschneidner, Jr. V. K. Pecharsky D. L. Schlagel T. A. Lograsso 

作者机构：Materials and Engineering Physics Program Ames Laboratory of the United States Department of Energy Iowa State University Ames Iowa 50011-3020 USA Department of Materials Science and Engineering Iowa State University Ames Iowa 50011-2300 USA 

出 版 物：《Physical Review B》 (Phys. Rev. B Condens. Matter Mater. Phys.)

年 卷 期：2004年第70卷第14期

页      面：144419-144419页

核心收录：

基　　金：Office of Basic Energy Sciences U.S. Department of Energy, USDOE 

摘      要：The room temperature crystal structures of Er5SixGe4−x alloys change systematically with the concentration of Ge from the orthorhombic Gd5Si4-type when x=4, to the monoclinic Gd5Si2Ge2 type when 3.5⩽x⩽3.9 and to the orthorhombic Sm5Ge4 type for x⩽3. The Curie-Weiss behavior of Er5SixGe4−x materials is consistent with the Er3+ state. The compounds order magnetically below 30K, apparently adopting complex noncollinear magnetic structures with magnetization not reaching saturation in 50kOe magnetic fields. In Er5Si4, the structural-only transformation from the monoclinic Gd5Si2Ge2-type to the orthorhombic Gd5Si4-type phase occurs around 218K on heating. Intriguingly, the temperature of this polymorphic transformation is weakly dependent on magnetic fields as low as 40kOe (dT∕dH=−0.058K∕kOe) when the material is in the paramagnetic state nearly 200K above its spontaneous magnetic ordering temperature. It appears that a magnetostructural transition may be induced in the 5:4 erbium silicide at ∼18K and above by 75kOe and higher magnetic fields. Only Er5Si4 but none of the other studied Er5SixGe4−x alloys exhibit magnetic field induced transformations, which are quite common in the closely related Gd5SixGe4−x system. The magnetocaloric effects of the Er5SixGe4−x alloys are moderate.