Shin-etsu Chemical Co., Ltd.

Japan Atomic Energy Agency

Nissin Chemical Industry Co., Ltd.

Tetsuya Kume

Koichi Hirota

Hajime Nakamura

Tetsuya Ohashi

Hiroto Sugahara

Kazuaki Sakaki

Hirochika Naganawa

Kojiro Shimojo

Hiroaki Nagata

Masaki Ohashi

Masayuki Kamata

Masahiko Ikka

Junya Fukuda

Provided is a magnetic refrigeration material whose magnetic transition temperature has been adjusted with high accuracy and which includes at least a first predetermined magnetic refrigeration material and a second predetermined magnetic refrigeration material which differs from the first magnetic refrigeration material. The absolute value of the difference between the magnetic transition temperature of the present magnetic refrigeration material and a target magnetic transition temperature is 0.7 K or less. The content of the first magnetic refrigeration material and the content of the second magnetic refrigeration material are determined by the magnetic transition temperatures of the first magnetic refrigeration material and the second magnetic refrigeration material and by a target magnetic transition temperature of the magnetic refrigeration material.

Method for producing magnetic refrigeration material, and magnetic refrigeration material

There are provided a method for producing a magnetic refrigeration material whose magnetic transition temperature can be adjusted with high accuracy, and a magnetic refrigeration material whose magnetic transition temperature has been adjusted with high accuracy. The magnetic refrigeration material production method of the present invention includes the steps of: preparing a first predetermined magnetic refrigeration material and a second predetermined magnetic refrigeration material which differs from the first magnetic refrigeration material; and mixing the first magnetic refrigeration material and the second magnetic refrigeration material to obtain a third magnetic refrigeration material. The content of the first magnetic refrigeration material and the content of the second magnetic refrigeration material in the third magnetic refrigeration material are determined by the magnetic transition temperatures of the first magnetic refrigeration material and the second magnetic refrigeration material and by a target magnetic transition temperature of the third magnetic refrigeration material. The magnetic refrigeration material of the present invention includes at least a first predetermined magnetic refrigeration material and a second predetermined magnetic refrigeration material which differs from the first magnetic refrigeration material. The absolute value of the difference between the magnetic transition temperature of the present magnetic refrigeration material and a target magnetic transition temperature is 0.7 K or less.

An R&#x2014;Fe&#x2014;B base sintered magnet is provided comprising a main phase containing an HR rich phase of (R',HR)(Fe,(Co))B wherein R&#x2032; is an element selected from yttrium and rare earth elements exclusive of Dy, Tb and Ho, and essentially contains Nd, and HR is an element selected from Dy, Tb and Ho, and a grain boundary phase containing a (R&#x2032;,HR)&#x2014;Fe(Co)-Mphase in the form of an amorphous phase and/or nanocrystalline phase, the (R&#x2032;,HR)&#x2014;Fe(Co)-Mphase consisting essentially of 25-35 at % of (R&#x2032;,HR), 2-8 at % of Mwhich is at least one element selected from Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, up to 8 at % of Co, and the balance of Fe. The HR rich phase has a higher HR content than the HR content of the main phase at its center. The magnet produces a high coercivity despite a low content of Dy, Tb and Ho.

R-Fe-B sintered magnet

An R&#x2014;Fe&#x2014;B base sintered magnet is provided consisting essentially of R (which is at least two rare earth elements and essentially contains Nd and Pr), Mwhich is at least two of Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, Mwhich is at least one of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W, boron, and the balance of Fe, and containing an intermetallic compound R(Fe,(Co))B as a main phase. The magnet contains an R&#x2014;Fe(Co)-Mphase as a grain boundary phase, the R&#x2014;Fe(Co)-Mphase contains A phase which is crystalline with crystallites of at least 10 nm formed at grain boundary triple junctions, and B phase which is amorphous and/or nanocrystalline with crystallites of less than 10 nm formed at intergranular grain boundaries and optionally grain boundary triple junctions.

R-Fe-B sintered magnet and making method

An R&#x2014;Fe&#x2014;B base sintered magnet is prepared through the steps of providing an alloy fine powder having a predetermined composition, compression shaping the alloy fine powder in an applied magnetic field into a compact, sintering the compact at a temperature of 900-1,250&#xb0; C. into a sintered body, cooling the sintered body to 400&#xb0; C. or below, high-temperature heat treatment including placing a metal, compound or intermetallic compound containing HR which is Dy, Tb and/or Ho, on the surface of the sintered body, heating at a temperature from more than 950&#xb0; C. to 1,100&#xb0; C., for causing grain boundary diffusion of HR into the sintered body, and cooling to 400&#xb0; C. or below, and low-temperature heat treatment including heating at a temperature of 400-600&#xb0; C. and cooling to 300&#xb0; C. or below. The sintered magnet produces a high coercivity despite a low content of Dy, Tb and Ho.

Method for preparing R&#x2014;Fe&#x2014;B sintered magnet

An R&#x2014;Fe&#x2014;B base sintered magnet is provided comprising a main phase containing an HR rich phase of (R', HR)(Fe,(Co))B wherein R&#x2032; is an element selected from yttrium and rare earth elements exclusive of Dy, Tb and Ho, and essentially contains Nd, and HR is an element selected from Dy, Tb and Ho, and a grain boundary phase containing a (R&#x2032;, HR)&#x2014;Fe(Co)-Mphase in the form of an amorphous phase and/or nanocrystalline phase, the (R&#x2032;, HR)&#x2014;Fe(Co)-Mphase consisting essentially of 25-35 at % of (R&#x2032;, HR), 2-8 at % of Mwhich is at least one element selected from Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, up to 8 at % of Co, and the balance of Fe. The HR rich phase has a higher HR content than the HR content of the main phase at its center. The magnet produces a high coercivity despite a low content of Dy, Tb and Ho.

The invention provides an R&#x2014;Fe&#x2014;B sintered magnet consisting essentially of 12-17 at % of Nd, Pr and R, 0.1-3 at % of M, 0.05-0.5 at % of M, 4.8+2*m to 5.9+2*m at % of B, and the balance of Fe, containing R(Fe,(Co))B intermetallic compound as a main phase, and having a core/shell structure that the main phase is covered with a grain boundary phases. The sintered magnet has an average grain size of less than 6 &#x3bc;m, a crystal orientation of more than 98%, and a degree of magnetization of more than 96%, and exhibits a coercivity of at least 10 kOe despite a low or nil content of Dy, Tb, and Ho.

The invention provides an R&#x2014;Fe&#x2014;B sintered magnet consisting essentially of 12-17 at % of Nd, Pr and R, 0.1-3 at % of M, 0.05-0.5 at % of M, 4.8+2*m to 5.9+2*m at % of B, and the balance of Fe, containing R(Fe,(Co))B intermetallic compound as a main phase, and having a core/shell structure that the main phase is covered with grain boundary phases. The sintered magnet exhibits a coercivity of at least 10 kOe despite a low or nil content of Dy, Tb and Ho.

R&#x2014;Fe&#x2014;B sintered magnet and making method

The invention provides an R&#x2014;Fe&#x2014;B sintered magnet consisting essentially of 12-17 at % of R, 0.1-3 at % of M, 0.05-0.5 at % of M, 4.8+2*m to 5.9+2*m at % of B, and the balance of Fe, containing R(Fe,(Co))B intermetallic compound as a main phase, and having a core/shell structure that the main phase is covered with a HR-rich layer and a (R,HR)&#x2014;Fe(Co)-Mphase wherein HR is Tb, Dy or Ho. The sintered magnet exhibits a coercivity &#x2267;10 kOe despite a low content of Dy, Tb, and Ho.

R-Fe&#x2014;B sintered magnet and making method

A rare earth metal extractant containing, as the extractant component, dialkyldiglycol amide acid which is excellent in breaking down light rare earth elements is reacted in diglycolic acid (X mol) and an esterification agent (Y mol) at a reaction temperature of 70&#xb0; C. or more and for a reaction time of one hour or more such that the mol ratio of Y/X is 2.5 or more, and is subjected to vacuum concentration. Subsequently, a reaction intermediate product is obtained by removing unreacted products and reaction residue. Then a nonpolar or low-polar solvent which is an organic solvent for forming an organic phase during solvent extraction of the rare earth metal and which is capable of dissolving dialkyldiglycol amide acid is added as the reaction solvent, and the reaction intermediate product is reacted with dialkyl amine (Z mol) such that the mol ratio of Z/X is 0.9 or more.

Method for synthesizing rare earth metal extractant

A rare earth metal extractant in the form of a dialkyl diglycol amic acid is synthesized by reacting diglycolic anhydride with a dialkylamine in an aprotic polar solvent, with a molar ratio of dialkylamine to diglycolic anhydride being at least 1.0, and removing the aprotic polar solvent.

Synthesis of rare earth metal extractant

A rare earth metal extractant containing, as the extractant component, dialkyldiglycol amide acid which is excellent in breaking down light rare earth elements is reacted in diglycolic acid (X mol) and an esterification agent (Y mol) at a reaction temperature of 70&#xb0; C. or more and for a reaction time of one hour or more such that the mol ratio of Y/X is 2.5 or more, and is subjected to vacuum concentration. Subsequently, a reaction intermediate product is obtained by removing unreacted products and reaction residue, and an aprotic polar solvent is added as the reaction solvent. Then, the reaction intermediate product is reacted with dialkyl amine (Z mol) such that the mol ratio of Z/X is 0.9 or more and the aprotic polar solvent is removed. As a consequence, a rare earth metal extractant is efficiently synthesized at a low cost and at a high yield without having to use expensive diglycolic acid anhydride and harmful dichloromethane.

A rare earth metal extractant in the form of a dialkyl diglycol amic acid is synthesized by reacting diglycolic anhydride with a dialkylamine in a synthesis medium. A molar ratio (B/A) of dialkylamine (B) to diglycolic anhydride (A) is at least 1.0. A non-polar or low-polar solvent in which the dialkyl diglycol amic acid is dissolvable is used as the synthesis medium.

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Echizen, Japan

Tetsuya Kume