Phase relationships, and structural, magnetic, and magnetocaloric properties in the Ce5Si4-Ce5Ge4 system

TitlePhase relationships, and structural, magnetic, and magnetocaloric properties in the Ce5Si4-Ce5Ge4 system
Publication TypeJournal Article
Year of Publication2010
AuthorsZhang H, Mudryk Y, Cao Q, Pecharsky VK, Gschneidner KA, Long Y
Journal TitleJournal of Applied Physics
Date Published01/01
ISBN Number0021-8979
Accession NumberISI:000273689600058
Keywordscerium alloys, crystal structure, crystal-structure, curie temperature, entropy, gd-5(sixge1-, germanium alloys, ground states, magnetisation, magnetocaloric effects, rare earth-germanium, silicon alloys, silicon compounds, space groups, x-ray diffraction

The crystallography, phase relationships, and magnetic properties of the Ce5Si4-xGex alloys with 0 < x < 4 have been investigated by using x-ray powder diffraction and isothermal magnetization measurements. There are three different crystal structures in the Ce5Si4-xGex system: the Zr5Si4-type tetragonal structure with space group P4(1)2(1)2 exists from 0 < x < 2.15, the Gd5Si2Ge2-type monoclinic structure with space group P112(1)/a exists at x approximate to 2.225, and the Sm5Ge4-type orthorhombic structure with space group Pnma is found for 2.4 < x < 4. The magnetic ordering temperature increases when the tetragonal phase changes to the monoclinic phase, and then it remains composition independent throughout the orthorhombic phase, which is the opposite trend compared to that observed in the heavy lanthanide 5:4 compounds when Ge content increases. Another distinct difference is that Ce5Si4 exhibits an antiferromagnetic ground state while Ce5Ge4 phase orders ferromagnetically, which is reverse compared to the R5Si4-xGex systems where R=Gd and Tb. The magnetocaloric effect has been calculated from the magnetization data. The Ce5Ge4 has the maximum magnetic entropy change Delta S-M(-11.6 J/kg K) at the Curie temperature of 11.5 K for a field change of 5 T.

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