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Rare-Earth Garnets and Perovskites for Space-Based ADR Cooling at High T and Low HFuture NASA satellite detector systems must be cooled to the 0.1 K temperature range to meet the stringent energy resolution and sensitivity requirements demanded by mid-term astronomy missions. The development of adiabatic demagnetization refrigeration (ADR) materials that can efficiently cool from the passive radiative cooling limit of approx. 30 K down to sub-Kelvin under low magnetic fields (H less than or equal to 3 T) would represent a significant improvement in space-based cooling technology. Governed by these engineering goals, our efforts have focused on quantifying the change in magnetic entropy of rare-earth garnets and perovskites. Various compositions within the gadolinium gallium iron garnet solid solution series (GGIG, Gd3Ga(5-x)Fe(x)O12, 0.00 less than or equal to X less than or equal to 5.00) and gadolinium aluminum perovskite (GAP, GdAlO3) have been synthesized via an organometallic complex approach and confirmed with powder x-ray diffraction. The magnetization of the GGIG and GAP materials has been measured as a function of composition (0.00 less than or equal to X less than or equal to 5.00), temperature (2 K less than or equal to T less than or equal to 30 K) and applied magnetic field (0 T less than or equal to H less than or equal to 3 T). The magnetic entropy change (DeltaS(sub mag)) between 0 T and 3 T was determined from the magnetization data. In the GGIG system, DeltaS(sub mag) was compositionally dependent; Fe(sup 3+) additions up to X less than or equal to 2.44 increased DeltaS(sub mag) at T > 5 K. For GAP, DeltaS(sub mag) was similar to that of GGIG, X = 0.00, both in terms of magnitude and temperature dependence at T > 10 K. However, the DeltaS(sub mag) of GAP at T < 10 K was less than the endmember GGIG composition, X = 0.00, and exhibited maximum approx. 5 K.
Document ID
20010069511
Acquisition Source
Goddard Space Flight Center
Document Type
Other
Authors
King, T. T.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Rowlett, B. A.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Ramirez, R. A.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Shirron, P. J.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Canavan, E. R.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
DiPirro, M. J.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Panek, J. S.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Tuttle, J. G.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Shull, R. D.
(National Inst. of Standards and Technology Gaithersburg, MD United States)
Fry, R. A.
(National Inst. of Standards and Technology Gaithersburg, MD United States)
Brodeur, Stephen J.
Date Acquired
August 20, 2013
Publication Date
January 1, 2001
Subject Category
Instrumentation And Photography
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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