Apparatus to determine the heat capacity and thermal conductivity of a material from 1 to 300 K in magnetic fields up to 9 T

Conference · Sat Jan 01 00:00:00 EST 1983

DOI:https://doi.org/10.1007/978-1-4613-9868-4_49· OSTI ID:5692145

Barclay, J A; Stewart, W F; Overton, W C; Chesebrough, R; McCray, M; McMillan, D

Magnetic refrigeration is a new technology that potentially offers refrigeration efficiencies > 50% of Carnot, compactness, and high reliability. Studies indicate that approx. 35% of Carnot efficiency is generally the best that is now possible for gas compression/expansion systems and, at that, only for very large plants; for smaller machines, the fraction of Carnot efficiency can become very small, e.g., 1-W refrigerators generally operate at 2 to 8% of Carnot efficiency. For magnetic refrigerators, the compression/expansion processes are replaced by a cycle involving the application/removal of a magnetic field to either a paramagnetic or ferromagnetic material (generally, paramagnets are used below approx. 20K and ferromagnets above). The thermodynamic cycles in gas and magnetic systems are analogous. Central to the development of magnetic refrigerators is the characterization of magnetic working substances. Among the key properties for which we require data are the heat capacity (from which we derive the entropy) and the thermal conductivity as functions of temperature and magnetic field. Accordingly, at the Los Alamos National Laboratory, we have designed and constructed an apparatus to make measurements of these quantities over the range 1 to 300 K at fields up to 9 T. We describe the methodology of these measurements, the versatile apparatus for making them, and results on GdNi, the first sample measured.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5692145
• Report Number(s): LA-UR-83-2378; CONF-830841-6; ON: DE83017228
• Resource Relation: Conference: Cryogenic engineering conference and international cryogenic materials conference, Colorado Springs, CO, USA, 15 Aug 1983
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
36 MATERIALS SCIENCE
GADOLINIUM ALLOYS
SPECIFIC HEAT
THERMAL CONDUCTIVITY
MAGNETIC REFRIGERATORS
MATERIALS
NICKEL ALLOYS
MEASURING INSTRUMENTS
LOW TEMPERATURE
MAGNETIC FIELDS
ULTRALOW TEMPERATURE
VERY LOW TEMPERATURE
ALLOYS
PHYSICAL PROPERTIES
RARE EARTH ALLOYS
REFRIGERATORS
THERMODYNAMIC PROPERTIES
420201* - Engineering- Cryogenic Equipment & Devices
360104 - Metals & Alloys- Physical Properties