Rare-earth Magnetic Materials Research Articles

Will Nd–Fe–B Magnets be Competitive Against Ferrites in the Automotive Industry?

A design study has been carried out to assess the benefits obtainable from substituting Nd–Fe–B for ferrite in permanent magnet motors used for automotive applications. It is concluded that the benefits obtained from use of Nd–Fe–B magnets are less than would be expected from the energy ratios of the two materials and that the weight savings obtained cannot be justified in terms of cost owing to the greatly increased price of rare earth magnetic materials. It is thus predicted that ferrites will remain the dominant magnet material in these applications for the foreseeable future, possibly even becoming more competitive as manufacturing techniques are refined, while use of Nd–Fe–B materials will be restricted to a few niche applications where the cost penalties are justified by improved performance. PM/0469

Magnetocaloric effects in rare-earth magnetic materials

A review is given of the experimental investigations of the magnetocaloric effect (MCE) in rare-earth magnetic materials of different classes: heavy rare-earth metals and their alloys, iron garnets, and intermetallic compounds. The results of measurements of the MCE near phase transitions are given for the vicinity of the Curie and Ne?l temperatures, and also near magnetic compensation points in the case of ferromagnetism-helicoidal antiferromagnetism and helicoidal ferromagnetism?paramagnetism transitions. The contributions to the MCE made by the various magnetic sublattices in rare-earth ferromagnets are identified. Measurements of the MCE in single crystals of alloys of heavy rare-earth metals have made it possible to identify the main energy contributions to the helicoidal antiferromagnetism-ferromagnetism phase transitions and their energy dependences. The concluding section of the review deals with the technical applications of the MCE exhibited by rare-earth magnetic materials. An analysis is made of the potential applications as refrigerants in magnetic refrigerators, in thermodynamic cycles, and in structures of various types.

ChemInform Abstract: Preparation and Fabrication of Rare Earth Magnetic Materials

ChemInformVolume 20, Issue 15 Reviews ChemInform Abstract: Preparation and Fabrication of Rare Earth Magnetic Materials B. J. BEAUDRY, B. J. BEAUDRY Mater. Prep. Cent., Iowa State Univ., Ames, IA, USASearch for more papers by this author B. J. BEAUDRY, B. J. BEAUDRY Mater. Prep. Cent., Iowa State Univ., Ames, IA, USASearch for more papers by this author First published: April 11, 1989 https://doi.org/10.1002/chin.198915349Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume20, Issue15April 11, 1989 RelatedInformation

Magnitokaloricheskie effekty v redkozemel'nykh magnetikakh

Magnitokaloricheskie effekty v redkozemel'nykh magnetikakh

Slotless construction for small synchronous motors using samarium cobalt magnets

Rare-earth magnet materials offer the possibility of slotless designs for miniature motors. Comparative analyses of slotted and slotless designs are presented for 2-pole permanent-magnet synchronous motors where the magnet has a linear demagnetisation characteristic. Experimental results are given for the magnet field of the slotless design in which the magnet end effect is considered. Results from an experimental slotless motor having a plastics-bonded rare-earth magnet rotor are included.

A linear synchronous motor for urban transit using rare-earth magnets

This paper describes a track-powered propulsion system for automated urban transit vehicles. It is a linear synchronous motor which is similar in principle to the motor previously designed for the Canadian 500 km/h Maglev system. The urban vehicle has an array of samarium-cobalt magnets fixed to a backing plate on the underside of the vehicle. These magnets interact with insulated aluminum cables imbedded in the track surface and carrying variable-frequency current supplied from periodically-placed track-side inverter stations. No iron is used in the track. The vehicle is suspended on wheels. The air gap clearance between the vehicle magnets and the track surface is about 40 mm. The paper describes a typical design in which the propulsion system, operating at maximum power output of 240 kW, has an efficiency of 77% and a power factor of 88%, using inverters with 200 m spacing. The system appears to have excellent technical and control features. Its economy will depend on the future cost of rare-earth magnet material.

Crystal field effects in amorphous rare earth magnetic materials

A model proposed by Harris et al. in which crystal field affects are important, is extended to consider the magnetic properties of amorphous materials containing localized ionic moments of a single, heavy rare earth, magnetic element. The paramagnetic and ferromagnetic properties are investigated for all the heavy rare earths. It is found that the average spontaneous moment per ion in the amorphous state can be lowered below the free ion moment by more than 50%, but the relative reduction in Curie temperature is much less marked than found by Harris et al.