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The Effects of Small Metal Additions (Co,Cu,Ga,Mn,Al,Bi,Sn) on the Magnetocaloric Properties of the Gd5Ge2Si2 Alloy

  • R D Shull
  • , V Provenzano
  • , A J Shapiro
  • , A Fu
  • , Michael W. Lufaso
  • , J Karapetrova
  • , G Kletetschka
  • , V Mikula

Producción científica: Articlerevisión exhaustiva

Resumen

<p> The structural and magnetic properties of arc-melted and homogenized (1300&thinsp;&deg;C, 1&emsp13;h) alloys of Gd <sub> 5 </sub> Ge <sub> 1.9 </sub> Si <sub> 2 </sub> <em> X </em> <sub> 0.1 </sub> ( <em> X </em> = Cu, Co, Ga, Mn, Al, Bi, or Sn) were investigated by powder x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and magnetometry. The addition of Cu, Ga, Mn, and Al completely eliminated the large hysteresis losses present in the undoped Gd <sub> 5 </sub> Ge <sub> 2 </sub> Si <sub> 2 </sub> alloy between 270 and 330&emsp13;K, broadened the magnetic entropy change &Delta; <em> S </em> <em> m </em> peak, and shifted its peak value from 275 to 305&emsp13;K similar to that observed earlier for Gd <sub> 5 </sub> Ge <sub> 1.9 </sub> Si <sub> 2 </sub> Fe <sub> 0.1 </sub> . The addition of Bi or Sn had a negligible effect on either the alloy hysteresis losses or the characteristics of the &Delta; <em> S </em> <sub> <em> m </em> </sub> vs <em> T </em> peak. The microstructure of the alloy doped with Cu, Co, Ga, Mn, or Al consisted of a majority phase (depleted of silicon) and a minor intergranular phase (rich in silicon and of the corresponding metal additive). For Bi or Sn doping, the microstructure consisted of only the Gd <sub> 5 </sub> Ge <sub> 2 </sub> Si <sub> 2 </sub> phase. Low temperature x-ray diffraction data on an Fe-doped sample showed the same spectra at 245 and 300&emsp13;K, consistent with the majority phase possessing an orthorhombic structure. Refrigeration capacity calculations show that Gd <sub> 5 </sub> Ge <sub> 1.9 </sub> Si <sub> 2 </sub> <em> X </em> <sub> 0.1 </sub> ( <em> X </em> = Fe,Cu,Co,Ga,Mn,&emsp13;or&emsp13;Al) alloys are superior magnetic refrigerants compared to the undoped Gd <sub> 5 </sub> Ge <sub> 2 </sub> Si <sub> 2 </sub> alloy.</p>
Idioma originalAmerican English
PublicaciónJournal of Applied Physics
Volumen99
EstadoPublished - ene 2006

Disciplines

  • Chemistry

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Profundice en los temas de investigación de 'The Effects of Small Metal Additions (Co,Cu,Ga,Mn,Al,Bi,Sn) on the Magnetocaloric Properties of the Gd5Ge2Si2 Alloy'. En conjunto forman una huella única.

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