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Title: Magnetic, Caloric and Crystallographic Properties of Dy5(SixGe1-x)4 Alloys

Thesis/Dissertation ·
DOI:https://doi.org/10.2172/798522· OSTI ID:798522
 [1]
  1. Iowa State Univ., Ames, IA (United States)
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A study of a series of Dy5(SixGe1-x)4 alloys using dc and ac magnetic susceptibility, magnetization, heat capacity, and x-ray powder diffraction techniques revealed that the variation of the magnetic properties and crystal structures with composition is similar to that observed in the Gd5(SixGe1-x)4 system, except that the magnetic ordering temperatures are lower. The magnetic phase transition temperatures vary from ~ 46K (Dy5Ge4) to ~ 137K (Dy5Si4). The intermediate ternary phase Dy5Si3Ge undergoes a first order magnetic phase transition at ~ 65K. The value of magnetic entropy change for this composition is quite large (-34J/kgK for magnetic field change from 0 to 50kOe), compared to the values for the two end members (-7 J/kgK for Dy5Ge4 and -12.5J/kgK for Dy5Si4). The magnetization and ac susceptibility measurements showed that alloys with monoclinic crystal structure have a non-collinear ordering of the magnetic moments at low temperatures. The alloy Dy5Si3Ge appears to exhibit a FM phase transition below the Curie temperature at 65K. Also a series of critical fields are observed at low temperature during magnetization vs magnetic field measurements in all of the Dy5(SixGe1-x)4 alloys regardless type of crystal structure. The Dy5(SixGe1-x)4 alloys, where 0.67≤x≤1, may be useful magnetic refrigerant materials in the ~50 to ~160K temperature range.

Research Organization:
Ames Lab., Ames, IA (United States)
Sponsoring Organization:
USDOE Office of Science (SC)
DOE Contract Number:
W-7405-Eng-82
OSTI ID:
798522
Report Number(s):
IS-T 2075; TRN: US200221%%1837
Resource Relation:
Other Information: TH: Thesis (M.S.); Submitted to Iowa State Univ., Ames, IA (US); PBD: 1 Aug 2002
Country of Publication:
United States
Language:
English

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Related Subjects

36 MATERIALS SCIENCE
ALLOYS
MAGNETIC PROPERTIES
CRYSTALLOGRAPHY
AMES LABORATORY