Loading patent…
AssigneeIowa State University Research Foundation, Inc.
InventorsKarl A. Gschneidner, Jr., Vitalij K. Pecharsky
Estimating the term…
Active magnetic regenerator and method using Gd.sub.5 (Si.sub.x Ge.sub.1-x).sub.4, where x is equal to or less than 0.5, as a magnetic refrigerant that exhibits a reversible ferromagnetic/antiferromagnetic or ferromagnetic-II/ferromagnetic-I first order phase transition and extraordinary magneto-thermal properties, such as a giant magnetocaloric effect, that renders the refrigerant more efficient and useful than existing magnetic refrigerants for commercialization of magnetic regenerators. The reversible first order phase transition is tunable from approximately 30 K to approximately 290 K (near room temperature) and above by compositional adjustments. The active magnetic regenerator and method can function for refrigerating, air conditioning, and liquefying low temperature cryogens with significantly improved efficiency and operating temperature range from approximately 10 K to 300 K and above. Also an active magnetic regenerator and method using Gd.sub.5 (Si.sub.x Ge.sub.1-x).sub.4, where x is equal to or greater than 0.5, as a magnetic heater/refrigerant that exhibits a reversible ferromagnetic/paramagnetic second order phase transition with large magneto-thermal properties, such as a large magnetocaloric effect that permits the commercialization of a magnetic heat pump and/or refrigerant. This second order phase transition is tunable from approximately 280 K (near room temperature) to approximately 350 K by composition adjustments. The active magnetic regenerator and method can function for low level heating for climate control for buildings, homes and automobile, and chemical processing.
A magnetic refrigerant for a magnetic regenerator consisting essentially of about 53 to about 58 atomic % Gd, up to about 47 atomic % Ge, and up to about 47 atomic % Si exhibiting a reversible ferromagnetic to antiferromagnetic or ferrromagnetic-II to ferromagnetic-I first order phase transition with changing temperature and magnetic field that provides a magnetic entropy change that is at least twice that exhibited by polycrystalline Gd.
A magnetic refrigerant for a magnetic regenerator consisting essentially of about 53 to about 58 atomic % Gd, about 6 to about 25 atomic % Si, and about 20 to about 38 atomic % Ge having a monoclinic crystal structure and a reversible ferromagnetic-II to ferromagnetic-I first order phase transition with changing temperature and magnetic field.
A magnetic refrigerant for a magnetic regenerator consisting essentially of Gd.sub.5 (Si.sub.x Ge.sub.1-x) where x is equal to or less than about 0.55 and exhibiting a reversible ferromagnetic to antiferromagnetic or ferrromagnetic-II to ferromagnetic-I first order phase transition with changing temperature and magnetic field that provides a magnetic entropy change that is at least twice that exhibited by polycrystalline Gd.
A magnetic refrigerant for a magnetic regenerator consisting essentially of Gd.sub.5 (Si.sub.x Ge.sub.1-x).sub.4 where x is about 0.2 to about 0.5 having a monoclinic crystal structure and exhibiting a reversible ferromagnetic-II to ferromagnetic-I first order phase transition with changing temperature and magnetic field.
A magnetic regenerator having means for providing a magnetic field and a working medium subjected to said magnetic field and consisting essentially of about 53 to about 58 atomic % Gd, up to about 47 atomic % Si, and up to about 47 atomic % Ge exhibiting a reversible ferromagnetic to antiferromagnetic or ferrromagnetic-II to ferromagnetic-I first order phase transition with changing temperature and magnetic field.
A method of magnetic regenerating comprising subjecting a working medium to a magnetic field wherein said working medium consists essentially of about 53 to about 58 atomic % Gd, up to about 47 atomic % Ge, and up to about 47 atomic % Si, exhibiting a reversible ferromagnetic to antiferromagnetic or ferrromagnetic-II to ferromagnetic-I first order phase transition with changing temperature and magnetic field.
Dependencies are inferred from the claim text.