-
Chapter
New Magnetic Refrigeration Materials for the Liquefaction of Hydrogen
Five heavy lanthanide ferromagnetic intermetallic compounds were studied as potential magnetic refrigerants for the liquefaction of hydrogen gas. (Dy0.5Er0.5)Al2 and TbNi2 appear to be better refrigerants than Gd...
-
Article
Copper(I) hexafluorosilicateπ-complexes with allylammonium salts. Synthesis and crystal structure of [CuOOCH·C3H5NH3]2SiF6 and [Cu2Cl3·2C3H5NH3]2SiF6
Two novel copper (I) π-complexes containing the SiF 6 2− anion have been synthesized and studied by X-ray structure analysis. The crystals of the first title c...
-
Chapter
New Ternary Magnetic Lanthanide Regenerator Materials for the Low-Temperature Stage of a Gifford-McMahon (G-M) Cryocooler
Four new alloys Er6Ni2Sn, Er6Ni2Pb, Er6Ni2(Sn0.75Ga0.25), and 50:50 Er6Ni2Sn/Er3Ni have been prepared and studied as potential candidate materials for the lower temperature stage of Gifford-McMahon (G-M) cryocool...
-
Chapter
The (Dy1-xErx)Al2 Alloys as Active Magnetic Regenerators for Magnetic Refrigeration
The low temperature properties (heat capacity from 3 to 350 K in fields up to 10 T, and both ac magnetic susceptibility and dc magnetic susceptibility and magnetization from 4 to 325 K in dc fields up to 5.5 T...
-
Chapter
Processing and Testing of the Low-Temperature Stage Er6Ni2Sn Cryogenic Regenerator Alloy
Low temperature heat capacity measurements have shown that Er6Ni2Sn might be a useful low temperature, <20 K, cryocooler regenerator material. Here we report on (1) our efforts to prepare small particles for use ...
-
Chapter
Comparison of the Magnetocaloric Effect Derived from Heat Capacity, Direct, and Magnetization Measurements
A theoretical and experimental evaluation of the experimental method for determining the magnetocaloric properties of magnetic materials show that the magnetic field heat capacity data can provide a reliable r...
-
Chapter
New Er-Based Materials for Active Magnetic Refrigeration Below 20K
High magnetic field (0 to 9.85 T) low temperature (1.2 to 30 K) heat capacity of five as-cast alloys: Er3AlC, Er3AlC0.5, Er3AlC0.25, Er3AlC0.1 and ErAgGa revealed that four of them can be used as efficient active...
-
Chapter
Utilization of the Magnetic Entropy in Active Magnetic Regenerator Materials
The magnetic entropy associated with magnetic ordering has been determined for ~20 lanthanide materials and it varies from ~60 to ~90% of the theoretical Rln (2J+l) value. The utilization of this entropy in th...
-
Chapter
Influence of Alloying on the Behavior and Properties of Er3Ni
A study on processing and alloying of the passive magnetic regenerator material Er3Ni revealed that the cooling rates of the order of 106 K/sec are insufficient to quench it into a glassy state. Small additions o...
-
Article
Benefits of Rapid Solidification Processing of Modified LaNi5 Alloys by High Pressure Gas Atomization for Battery Applications
A high pressure gas atomization approach to rapid solidification has been employed to investigate simplified processing of Sn modified LaNi5 powders that can be used for advanced Ni/metal hydride (Ni/MH) batterie...
-
Chapter
The Influence of Multiple Magnetic Ordering on the Magnetocaloric Effect in RNiAl Alloys
Both the change in magnetic entropy (ΔSmag) and the adiabatic temperature rise (ΔTad) induced by a change of magnetic field were determined for a series of (Gd1-xErx)NiAl alloys (where x = 0, 0.30, 0.46, 0.60, 0....
-
Chapter
The Giant Magnetocaloric Effect in Gd5(SixGe1-x)4 Materials for Magnetic Refrigeration
The Gd5(SixGe1-x)4 alloys, where 0 ≤ x ≤ 0.5, exhibit a giant magnetocaloric effect. This extremely large magnetocaloric effect should elevate magnetic refrigeration technology to new heights allowing it to becom...
-
Article
Gas Atomization Processing of LaNi5−xMm, Modified with Silicon and Tin
A high pressure gas atomization (HPGA) process has been employed to study microsegregation in LaNi4.75 Sn0.25 and LaNi4.6Si0.4 alloy powders to serve as a basis for further investigations of low cost production o...
-
Article
The standard state of cerium
Based on two studies carried out about 20 years apart, it was found that the double close-packed hexagonal βCe phase slowly transformed to the face-centered cubic γCe phase at room temperature and ambient pres...
-
Chapter
Magnetocaloric Effect in GdAl2 and Nd2Fe17
The magnetocaloric properties of GdAl2 and Nd2Fe17 have been determined by three methods: (1) measured directly in pulsed (∼0.2 s duration) and semi-static magnetic fields; (2) calculated from the heat capacity m...
-
Chapter
Magnetothermal Properties of Dy5(SixGe1−x)4 Alloys
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 a...
-
Chapter
Ductile, High Heat Capacity, Magnetic Regenerator Alloys for the 10 to 80 K Temperature Range
New erbium-based regenerator materials have been developed as a replacement for lead in low temperature cryocoolers. These alloys have volumetric heat capacities which are 20 to 185% larger than that of lead f...
-
Chapter
Gd-Zn Alloys as Active Magnetic Regenerator Materials for Magnetic Refrigeration
Stoichiometric GdZn crystallizes in the cubic CsCl-type crystal structure and has been reported to order ferromagnetically at 270 K. Experimental measurements of the magnetization and heat capacity of GdZn as ...
-
Chapter
Manufacturing Considerations for Rare Earth Powders Used in Cryocooler and Magnetic Refrigerator Applications
The high chemical reactivity and oxygen affinity of the rare earth metals make them especially difficult to produce and maintain as high purity powders. From the initial oxide reduction through bulk melt prepa...
-
Chapter
New Regenerator Materials for Use in Pulse Tube Coolers
A two-stage pulse tube cooler driven by a linear compressor is being developed to provide cooling at 20 K. The first stage of the cooler will have the conventional stainless steel screen regenerator matrix. Th...
