US3371042A - Ferromagnetic materials - Google Patents
Ferromagnetic materials Download PDFInfo
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- US3371042A US3371042A US428862A US42886265A US3371042A US 3371042 A US3371042 A US 3371042A US 428862 A US428862 A US 428862A US 42886265 A US42886265 A US 42886265A US 3371042 A US3371042 A US 3371042A
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- euo
- europium oxide
- curie temperature
- mixture
- monosulfide
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- 239000003302 ferromagnetic material Substances 0.000 title description 14
- 229910001940 europium oxide Inorganic materials 0.000 description 79
- AEBZCFFCDTZXHP-UHFFFAOYSA-N europium(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Eu+3].[Eu+3] AEBZCFFCDTZXHP-UHFFFAOYSA-N 0.000 description 78
- 230000005298 paramagnetic effect Effects 0.000 description 26
- 239000000203 mixture Substances 0.000 description 25
- 239000000376 reactant Substances 0.000 description 21
- 239000000463 material Substances 0.000 description 20
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 16
- MMXSKTNPRXHINM-UHFFFAOYSA-N cerium(3+);trisulfide Chemical compound [S-2].[S-2].[S-2].[Ce+3].[Ce+3] MMXSKTNPRXHINM-UHFFFAOYSA-N 0.000 description 12
- YTYSNXOWNOTGMY-UHFFFAOYSA-N lanthanum(3+);trisulfide Chemical compound [S-2].[S-2].[S-2].[La+3].[La+3] YTYSNXOWNOTGMY-UHFFFAOYSA-N 0.000 description 10
- 230000005291 magnetic effect Effects 0.000 description 10
- 239000008188 pellet Substances 0.000 description 10
- 230000003993 interaction Effects 0.000 description 8
- 238000000034 method Methods 0.000 description 8
- 229910052757 nitrogen Inorganic materials 0.000 description 8
- 150000002500 ions Chemical class 0.000 description 7
- 239000007788 liquid Substances 0.000 description 7
- 239000012071 phase Substances 0.000 description 6
- 229910052761 rare earth metal Inorganic materials 0.000 description 6
- 239000006104 solid solution Substances 0.000 description 6
- 229910052715 tantalum Inorganic materials 0.000 description 6
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 6
- FWVAXENAXYFLMB-UHFFFAOYSA-N 1-(2-methoxyethyl)-2,5-dimethylpyrrole-3-carboxylic acid Chemical class COCCN1C(C)=CC(C(O)=O)=C1C FWVAXENAXYFLMB-UHFFFAOYSA-N 0.000 description 5
- 229910052684 Cerium Inorganic materials 0.000 description 5
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 5
- -1 europium chalcogenide Chemical class 0.000 description 5
- 239000008240 homogeneous mixture Substances 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 229910052692 Dysprosium Inorganic materials 0.000 description 4
- 229910052691 Erbium Inorganic materials 0.000 description 4
- 229910052693 Europium Inorganic materials 0.000 description 4
- 229910052688 Gadolinium Inorganic materials 0.000 description 4
- 229910052689 Holmium Inorganic materials 0.000 description 4
- 229910052765 Lutetium Inorganic materials 0.000 description 4
- 229910052779 Neodymium Inorganic materials 0.000 description 4
- 229910052771 Terbium Inorganic materials 0.000 description 4
- 229910052775 Thulium Inorganic materials 0.000 description 4
- KBQHZAAAGSGFKK-UHFFFAOYSA-N dysprosium atom Chemical compound [Dy] KBQHZAAAGSGFKK-UHFFFAOYSA-N 0.000 description 4
- UYAHIZSMUZPPFV-UHFFFAOYSA-N erbium Chemical compound [Er] UYAHIZSMUZPPFV-UHFFFAOYSA-N 0.000 description 4
- 230000005294 ferromagnetic effect Effects 0.000 description 4
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 4
- KJZYNXUDTRRSPN-UHFFFAOYSA-N holmium atom Chemical compound [Ho] KJZYNXUDTRRSPN-UHFFFAOYSA-N 0.000 description 4
- 229910052746 lanthanum Inorganic materials 0.000 description 4
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 4
- 239000007791 liquid phase Substances 0.000 description 4
- OHSVLFRHMCKCQY-UHFFFAOYSA-N lutetium atom Chemical compound [Lu] OHSVLFRHMCKCQY-UHFFFAOYSA-N 0.000 description 4
- 239000004570 mortar (masonry) Substances 0.000 description 4
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 4
- 150000002910 rare earth metals Chemical group 0.000 description 4
- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 description 4
- FRNOGLGSGLTDKL-UHFFFAOYSA-N thulium atom Chemical compound [Tm] FRNOGLGSGLTDKL-UHFFFAOYSA-N 0.000 description 4
- 239000013078 crystal Substances 0.000 description 3
- 230000001747 exhibiting effect Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000004173 sunset yellow FCF Substances 0.000 description 3
- 229910052777 Praseodymium Inorganic materials 0.000 description 2
- 229910052772 Samarium Inorganic materials 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical group [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 150000002178 europium compounds Chemical class 0.000 description 2
- 239000000696 magnetic material Substances 0.000 description 2
- 230000005415 magnetization Effects 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 2
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 2
- 230000002269 spontaneous effect Effects 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- OGPBJKLSAFTDLK-UHFFFAOYSA-N europium atom Chemical compound [Eu] OGPBJKLSAFTDLK-UHFFFAOYSA-N 0.000 description 1
- 230000005307 ferromagnetism Effects 0.000 description 1
- 238000005290 field theory Methods 0.000 description 1
- YIAXEFITNBBEOD-UHFFFAOYSA-N gadolinium(3+) trisulfide Chemical compound [S--].[S--].[S--].[Gd+3].[Gd+3] YIAXEFITNBBEOD-UHFFFAOYSA-N 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- HYWYRSMBCFDLJT-UHFFFAOYSA-N nimesulide Chemical compound CS(=O)(=O)NC1=CC=C([N+]([O-])=O)C=C1OC1=CC=CC=C1 HYWYRSMBCFDLJT-UHFFFAOYSA-N 0.000 description 1
- 229960000965 nimesulide Drugs 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000003870 refractory metal Substances 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/0302—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity characterised by unspecified or heterogeneous hardness or specially adapted for magnetic hardness transitions
- H01F1/0311—Compounds
- H01F1/0313—Oxidic compounds
Definitions
- ABSTRACT OF THE DISCLQSURE Ferromagnetic compositions represented by the formula (EuO) (RS) in which 0.01 x 0.30 and R is a rare earth.
- the compositions are characterized by a Curie temperature which can be controlled between 73 K. and 132 K.
- This invention relates to a new series of europium compounds exhibiting a paramagnetic Curie temperature (0) which can be selectively varied between 73 K. and 132 K.
- the para magnetic Curie temperature (0) of such compounds is varied by changing the population of electrons in the d-orbitals of the base europium oxide (EuO) material while retaining the characteristically high magnetic moment thereof.
- EuO europium oxide
- EuO europium oxide
- N temperatures 77 K.
- the usefulness of europium oxide (EuO) would beobviously increased if the respective paramagnetic Curie temperature (0) exhibited thereby could be raised at least above the temperature of liquid nitrogen (N at atmospheric pressures.
- europium oxide (EuO) is higher than those of ferrites which, for example, have saturation moments below 6,000 gauss. Therefore, europium oxide (EuO) would provide a useful magnetic material for application where high magnetic moments are desired (high frequency transformer cores, microwave gyrators, etc.)
- EuO europium oxide
- Paramagnetic Curie temperature (0) is affected by changing the population of electrons in the europium oxide (EuO) to vary electron concentrations in the crystal lattice.
- EuO europium oxide
- molecular field theory magnetic interactions between electron spin moments is determinative of the paramagnetic Curie temperature (0).
- the interaction between magnetic spin moments which produces spontaneous magnetization in europium oxide (EuO) has been explained by the interaction between spin moments of the nearest neighbor europium (Eu) ions in the rock salt-type face centered cubic crystal structure of europium oxide (EuO).
- the paramagnetic Curie temperature (6) of europium oxide (EuO) is ad justed by forming a solid solution having the formula (EuO) (RS) where 0.0l x 0.30, (RS) is a monosulfide, and (R) is a rare earth selected, from the group consisting of lanthanum (La), praseodymium (Pr), neodymium (Nd), saznarium (SM), gadolinium (Gd), cerium (Ce), dysprosium (Dy), terbium (Tb), holmium (Ho), erbium (Er), thulium (Tm), and lutetium (Lu).
- the solid solution of the monosulfide (RS) in europium oxide (EuO) exhibits a substantial increase in paramagnetic temperature (0).
- Another object of this invention is to prepare a material exhibiting a relatively high magnetic moment and having a paramagnetic Curie temperature (0) in excess of liquid nitrogen (N temperatures (77 K.).
- Another object of this invention is to provide a process for controlling the Curie temperature (6) of magnetic materials formed of europium oxide (EuO).
- Another object of this invention is to provide a ferromagnetic material having the formula (EuO) (RS) where 0.0l x 0.30.
- the novel ferromagnetic material of this invention is prepared by homogeneously mixing appropriate predetermined quantities of the base europium oxide (EuO) and monosulfide material (RS), where (RS) is a monosulfide and (R) is a rare earth selected from the group consisting of lanthanum (La), praseodymium (Pr), neodymium (Nd), samarium (Sm), gadolinium (Gd), cerium (Ce), dysprosium (Dy), terbium (Tb), holmium (H0), erbium (Er), thulium (Tm), and lutetium (Lu).
- EuO base europium oxide
- RS monosulfide material
- R is a rare earth selected from the group consisting of lanthanum (La), praseodymium (Pr), neodymium (Nd), samarium (Sm), gadolinium (Gd), cerium (Ce
- the europium oxide (EuO) and monosulfide (RS), thus mixed, are heated to a reaction temperature at least lower than the decomposition temperature of either material and then cooled rapidly to room temperature.
- the quantity of monosulfide material (RS) added to the base europium oxide (EuO) material is determinative of the change in paramagnetic Curie temperature (0) of the reacted mixture, i.e., of the europium oxide (EuO).
- the reacted mixture may define at least a two-phase system, one such phase being a solid solution monosulfide of the (RS) and europium oxide (EuO).
- This procedure involved in forming the novel ferromagnetic material of this invention is to initially blend, e.g., by mechanical shaker, mortar and pestle, etc., appropriate amounts of the base europium oxide (E110) material and the modifying monosulfide material (RS), each in finely divided form, to obtain a homogeneous mixture,
- the homogeneous mixture of the base europium oxide (EuO) material and the monosulfide material (RS) are pressed into pellets, e.g., by a hydraulic press, and then heated to between l500 ing atmosphere.
- the pellets may be heated in a refractory metal crucible, e.g., molybdenum, tantalum, etc., which is evacuated and sealed.
- the mixture can be placed in an open crucible and heated in a reducing atmosphere, e.g., helium, argon, etc/In either event, the pellets are heated in the described temperature" C. and 1950 C. in a nonoxidiz-" range in excess of one hour so as to insure reaction of the base europium oxide (EuO) material and the monosulfide material (RS) to support the formation of a solid solution.
- a refractory metal crucible e.g., molybdenum, tantalum, etc.
- a reducing atmosphere e.g., helium, argon, etc/In either event, the pellets are heated in the described temperature" C. and 1950 C. in a nonoxidiz-" range in excess of one hour so as to insure reaction of the base
- the paramagnetic Curie temperature (6) is increased due to the introduction of additional electrons into the rock-salt structure of the base europium oxide (EuO) material by the monosulfide (RS) whereby the electron concentration of the former is increased. Since the (R) constituent, above identified, of the monosulfide (RS) material is trivalent, it can be theorized that the substitution of trivalent (R+++) ions for the (Eu++) ions in the lattice introduced electrons into the d shell of remaining (Eu++) ions in the lattice.
- Example 1 Ferromagnetic materials of this invention have been prepared in accordance with the following table where the following percentages in moles of europium oxide (E110) and cerium sul ide (CeS) were reacted to obtain the indicated paramagnetic Curie temperature (0).
- the reacted mixtures each formed a two-phase system and exhibited increased paramagnetic Curie temperature (6) which varied as the percentage by mole of the modifying cerium sulfide (CeS) material, as shown in Table I. Part of the reacted material had a rocksalt structure. When the percentage by mole of cerium sulfide (CeS) was increased to 5 percent, the reacted mixture exhibted ferromagnetic properties at 78 K. or above liquid nitrogen (N temperatures. Also, the reacted mixture exhibited increased electrical conductivity as the percentage by mole of cerium sulfide (CeS) was increased. The observed paramagnetic Curie temperature (0) of 130 K. when 70 percent by mole of europium oxide (EuO) was reacted with 30 percent by mole of cerium sulfide (CeS) was within experimental error.
- CeS cerium sulfide
- Example 2 Also, similar procedures have been employed to prepare ferromagnetic materials of this invention wherein the fol- 4 lowing percentages by mole of europium oxide (EuO) and lanthanum sulfide .(LaS) as shown in the Table II' were reacted to obtain the indicated paramagnetic Curie temperatures (0).
- EuO europium oxide
- LaS lanthanum sulfide
- Finely-powdered europium oxide (EuO) and lanthanum sulfide (LaS) materials were homogeneously mixed by mortar and pestle and pressed into pellets.
- the pellets were placed into an open tantalum crucible and heated at 1750 C. in a nitrogen (N atmosphere for approximately 8 hours and then cooled to room temperature within a 30- minute period. During the heat treatment, a portion of the mixture was observed to pass into the liquid phase.
- the paramagnetic Curie temperature (0) of the reacted mixture rose as indicated in Table II.
- the presence of 5 percent by mole of lanthanum sulfide (LaS) was effective to increase the paramagnetic Curie temperature (0) of the reacted mixture to approximately K., i.e., in excess of liquid nitrogen (N temperatures. Also, the reacted mixtures each formed a two-phase system and exhibited increased electrical conductivity as the PBICCHtage by mole of lanthanum sulfide (LaS) was increased.
- Example 3 Similar procedures were followed as in Examples 1 and 2 with respect to the europium oxide (EuO)-erbium sulfide (ErS) series. Fifteen percent by mole of erbium sulfide (ErS) was reacted with percent by mole of europium oxide (EuO). Again, finely-powedered europium oxide (EuO) and erbium sulfide (ErS) were homogeneously mixed by mortar and pestle, and pressed into pellets. The pellets were sealed, however, in an evacuated tantalum crucible and heated at 1750 C. for approximately 8 hours and cooled down to room temperature Within a 30 minute period.
- EuO europium oxide
- ErS europium oxide
- Example 4 Similar procedures were followed as in Example" 3 with respect to the europium oxide (EuO)-gad-' olinium sulfide (GdS) system.
- EuO europium oxide
- GdS gadolinium sulfide
- finely-- powdered europium oxide (EuO) and gadolinium sulfide (GdS) were formed in a homogeneous mixture of 85 percent-l5 percent by mole and pressed into pellets. The pellets were ealed in an evacuated tantalum crucible and heated at 1750 C. for approximately 8 hours. The reacted mixture was then cooled to room temperature within a 30 minute period. The reacted mixture formed a twophase system and exhibited a paramagnetic Curie temperature (0) of 130 K.
- La lanthanum
- Pr praseodymiurn
- Nd neodymium
- Sm samarium
- Gd gadolinium
- Ce cerium
- Dy dysprosium
- Tb terbium
- Ho holmium
- Er erbium
- Tm thulium
- Lu lutetium
- a ferromagnetic material having the formula )1 x( )x where 0.01 x 0.30.
- a ferromagnetic material having the formula )1 X( )x where 0.01 x 0.30.
- a ferromagnetic material having the formula where 0.01 x 0.30.
- a rare earth element selected from the group consisting of cerium (Ce), lanthanum (La), erb
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- Power Engineering (AREA)
- Hard Magnetic Materials (AREA)
Description
United States Patent FERROMAGNETIC MATERIALS Thomas R. McGuire and Merrill W. Shafer, Yorktown Heights, N.Y., assignors to International Business Machines Corporation, New York, N.Y., a corporation of New York No Drawing. Filed Jan. 28, 1965, Ser. No. 428,862
8 Claims. (Cl. 252 62.51)
ABSTRACT OF THE DISCLQSURE Ferromagnetic compositions represented by the formula (EuO) (RS) in which 0.01 x 0.30 and R is a rare earth. The compositions are characterized by a Curie temperature which can be controlled between 73 K. and 132 K.
This invention relates to a new series of europium compounds exhibiting a paramagnetic Curie temperature (0) which can be selectively varied between 73 K. and 132 K. In accordance with this invention, the para magnetic Curie temperature (0) of such compounds is varied by changing the population of electrons in the d-orbitals of the base europium oxide (EuO) material while retaining the characteristically high magnetic moment thereof.
With the discovery of ferromagnetism in the europium chalcogenide series, a new group of materials with device applications has become available. One such material is europium oxide (EuO) which exhibits desirable characteristics, i.e., high magnetic moment; however, europium oxide (EuO) exhibits a relatively low paramagnetic Curie temperature (0) of 73 K. Paramagnetic Curie temperature (0) is a measure of the ferromagnetic exchange interactions and is closely related to the Curie temperature where spontaneous magnetization occurs. Accordingly, present use of europium oxide for device applications is seriously limited since devices formed thereof cannot be operated at convenient temperatures, say liquid nitrogen (N temperatures (77 K.). The usefulness of europium oxide (EuO) would beobviously increased if the respective paramagnetic Curie temperature (0) exhibited thereby could be raised at least above the temperature of liquid nitrogen (N at atmospheric pressures.
The ferromagnetic saturation moment of europium oxide (EuO) is higher than those of ferrites which, for example, have saturation moments below 6,000 gauss. Therefore, europium oxide (EuO) would provide a useful magnetic material for application where high magnetic moments are desired (high frequency transformer cores, microwave gyrators, etc.)
Generally, the structure of europium oxide (EuO) can be characterized as having a half-filled 4f shell and an empty 5d shell. Paramagnetic Curie temperature (0) is affected by changing the population of electrons in the europium oxide (EuO) to vary electron concentrations in the crystal lattice. According to molecular field theory, magnetic interactions between electron spin moments is determinative of the paramagnetic Curie temperature (0). The interaction between magnetic spin moments which produces spontaneous magnetization in europium oxide (EuO) has been explained by the interaction between spin moments of the nearest neighbor europium (Eu) ions in the rock salt-type face centered cubic crystal structure of europium oxide (EuO). Reference is made to patent application Ser. No. 374,351, filed June 11, 1964, in the names of F. Holtzberg et al., entitled New Ferromagnetic Materials, and assigned to the assignee of this invention. Since the electron spin moments of the 4f and 5d shells of neighboring europium ions (Eu++) 3,371 ,042 Patented Feb. 27, 1968 overlap, there is a virtual occupation of the 5d shell which gives rise to exchange interactions. The virtual occupation of the S'd shell would allow the filling of the 1' orbitals which would overlap in the direction and effectively increase magnetic interactions between neighboring europium ions (Eu++) whereby the para-magnetic Curie temperature (9) is increased. The amount of increase in paramagnetic Curie temperature (0) varies as the increased electron concentration in the crystal lattice of the europium oxide (EuO).
In accordance with this invention, the paramagnetic Curie temperature (6) of europium oxide (EuO) is ad justed by forming a solid solution having the formula (EuO) (RS) where 0.0l x 0.30, (RS) is a monosulfide, and (R) is a rare earth selected, from the group consisting of lanthanum (La), praseodymium (Pr), neodymium (Nd), saznarium (SM), gadolinium (Gd), cerium (Ce), dysprosium (Dy), terbium (Tb), holmium (Ho), erbium (Er), thulium (Tm), and lutetium (Lu). In accordance with this invention, albeit a two-phase system may result, the solid solution of the monosulfide (RS) in europium oxide (EuO) exhibits a substantial increase in paramagnetic temperature (0).
It is an object of this invention to provide a new series of europium compounds exhibiting a Curie temperature (0) which can be controlled between 73 K. and 132 K.
Another object of this invention is to prepare a material exhibiting a relatively high magnetic moment and having a paramagnetic Curie temperature (0) in excess of liquid nitrogen (N temperatures (77 K.).
Another object of this invention is to provide a process for controlling the Curie temperature (6) of magnetic materials formed of europium oxide (EuO).
Another object of this invention is to provide a ferromagnetic material having the formula (EuO) (RS) where 0.0l x 0.30.
The novel ferromagnetic material of this invention is prepared by homogeneously mixing appropriate predetermined quantities of the base europium oxide (EuO) and monosulfide material (RS), where (RS) is a monosulfide and (R) is a rare earth selected from the group consisting of lanthanum (La), praseodymium (Pr), neodymium (Nd), samarium (Sm), gadolinium (Gd), cerium (Ce), dysprosium (Dy), terbium (Tb), holmium (H0), erbium (Er), thulium (Tm), and lutetium (Lu). The europium oxide (EuO) and monosulfide (RS), thus mixed, are heated to a reaction temperature at least lower than the decomposition temperature of either material and then cooled rapidly to room temperature. The quantity of monosulfide material (RS) added to the base europium oxide (EuO) material is determinative of the change in paramagnetic Curie temperature (0) of the reacted mixture, i.e., of the europium oxide (EuO). The reacted mixture may define at least a two-phase system, one such phase being a solid solution monosulfide of the (RS) and europium oxide (EuO).
This procedure involved in forming the novel ferromagnetic material of this invention is to initially blend, e.g., by mechanical shaker, mortar and pestle, etc., appropriate amounts of the base europium oxide (E110) material and the modifying monosulfide material (RS), each in finely divided form, to obtain a homogeneous mixture, The homogeneous mixture of the base europium oxide (EuO) material and the monosulfide material (RS) are pressed into pellets, e.g., by a hydraulic press, and then heated to between l500 ing atmosphere. For example, the pellets may be heated in a refractory metal crucible, e.g., molybdenum, tantalum, etc., which is evacuated and sealed. Alternatively, the mixture can be placed in an open crucible and heated in a reducing atmosphere, e.g., helium, argon, etc/In either event, the pellets are heated in the described temperature" C. and 1950 C. in a nonoxidiz-" range in excess of one hour so as to insure reaction of the base europium oxide (EuO) material and the monosulfide material (RS) to support the formation of a solid solution. Best results have been observed when the monosulfide (RS)-europium oxide (EuO) mixture is heated sufficiently to cause a portion of the mixture to pass into the liquid phase and rapidly cool to room temperature, for example, within 30 minutes. The reacted mixture, when cooled, retains the desired magnetic properties of europium oxide (EuO) but exhibits a paramagnetic Curie temperature which can be adjusted to exceed liquid nitrogen (N temperatures.
The paramagnetic Curie temperature (6) is increased due to the introduction of additional electrons into the rock-salt structure of the base europium oxide (EuO) material by the monosulfide (RS) whereby the electron concentration of the former is increased. Since the (R) constituent, above identified, of the monosulfide (RS) material is trivalent, it can be theorized that the substitution of trivalent (R+++) ions for the (Eu++) ions in the lattice introduced electrons into the d shell of remaining (Eu++) ions in the lattice. Due to the presence of the trivalent (R+++) ions, the 5d shells of the remaining (Eu++) ions are virtually occupied and magnetically coupled in the (110) direction so as to increase magnetic interaction between adjacent (Eu++) ions in the lattice. The resulting virtual occupation of the 5d shells (1 gives rise to exchange interactions eifective to increase the paramagnetic Curie temperature (0) in excess of liquid nitrogen (N temperature (77 K.).
Example 1 Ferromagnetic materials of this invention have been prepared in accordance with the following table where the following percentages in moles of europium oxide (E110) and cerium sul ide (CeS) were reacted to obtain the indicated paramagnetic Curie temperature (0).
TABLE I Para-magnetic E110 (moles) CeS (moles) Curie temperature The europium oxide (EuO) and cerium sulfide (CeS) materials in finely powdered form in the amounts shown in Table I were mixed by mortar and pestle to obtain a homogeneous mixture. The homogeneous mixture was pressed into pellets and placed in an open tantalum crucible. .The tantalum crucible was heated in an argon (Ar) atmosphere for approximately 8 hours at 1700 C., a portion of the mixture being observed to pass into the liquid phase, and cooled down to room temperature within a 30-minute period. The reacted mixtures each formed a two-phase system and exhibited increased paramagnetic Curie temperature (6) which varied as the percentage by mole of the modifying cerium sulfide (CeS) material, as shown in Table I. Part of the reacted material had a rocksalt structure. When the percentage by mole of cerium sulfide (CeS) was increased to 5 percent, the reacted mixture exhibted ferromagnetic properties at 78 K. or above liquid nitrogen (N temperatures. Also, the reacted mixture exhibited increased electrical conductivity as the percentage by mole of cerium sulfide (CeS) was increased. The observed paramagnetic Curie temperature (0) of 130 K. when 70 percent by mole of europium oxide (EuO) was reacted with 30 percent by mole of cerium sulfide (CeS) was within experimental error.
Example 2 Also, similar procedures have been employed to prepare ferromagnetic materials of this invention wherein the fol- 4 lowing percentages by mole of europium oxide (EuO) and lanthanum sulfide .(LaS) as shown in the Table II' were reacted to obtain the indicated paramagnetic Curie temperatures (0).
Finely-powdered europium oxide (EuO) and lanthanum sulfide (LaS) materials were homogeneously mixed by mortar and pestle and pressed into pellets. The pellets were placed into an open tantalum crucible and heated at 1750 C. in a nitrogen (N atmosphere for approximately 8 hours and then cooled to room temperature within a 30- minute period. During the heat treatment, a portion of the mixture was observed to pass into the liquid phase. As the percentage by mole of lanthanum sulfide (LaS) was increased, the paramagnetic Curie temperature (0) of the reacted mixture rose as indicated in Table II. The presence of 5 percent by mole of lanthanum sulfide (LaS) was effective to increase the paramagnetic Curie temperature (0) of the reacted mixture to approximately K., i.e., in excess of liquid nitrogen (N temperatures. Also, the reacted mixtures each formed a two-phase system and exhibited increased electrical conductivity as the PBICCHtage by mole of lanthanum sulfide (LaS) was increased.
Example 3 Similar procedures were followed as in Examples 1 and 2 with respect to the europium oxide (EuO)-erbium sulfide (ErS) series. Fifteen percent by mole of erbium sulfide (ErS) was reacted with percent by mole of europium oxide (EuO). Again, finely-powedered europium oxide (EuO) and erbium sulfide (ErS) were homogeneously mixed by mortar and pestle, and pressed into pellets. The pellets were sealed, however, in an evacuated tantalum crucible and heated at 1750 C. for approximately 8 hours and cooled down to room temperature Within a 30 minute period. The reacted mixture formed a two-phase system and exhibited a paramagnetic Curie temperature (0) of Example 4 Similar procedures were followed as in Example" 3 with respect to the europium oxide (EuO)-gad-' olinium sulfide (GdS) system. For example, finely-- powdered europium oxide (EuO) and gadolinium sulfide (GdS) were formed in a homogeneous mixture of 85 percent-l5 percent by mole and pressed into pellets. The pellets were ealed in an evacuated tantalum crucible and heated at 1750 C. for approximately 8 hours. The reacted mixture was then cooled to room temperature within a 30 minute period. The reacted mixture formed a twophase system and exhibited a paramagnetic Curie temperature (0) of 130 K.
Because of the similar chemical properties of the remaining reactants (RS), it is clear that similar solid solutions of europium oxide (EuO) and any of the (RS) monosulfides will give corresponding increases in paramagnetic Curie temperature (0).
While the invention has been particularly described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various. changes in form and details may be made therein without departing from the spirit and scope of the invention.
What is claimed is:
1. A ferromagnetic material having the formula 5 Where 0.0l x 0.30 and R is a rare earth element selected from the group consisting of lanthanum (La), praseodymiurn (Pr), neodymium (Nd), samarium (Sm), gadolinium (Gd), cerium (Ce), dysprosium (Dy), terbium (Tb), holmium (Ho), erbium (Er), thulium (Tm), and lutetium (Lu).
2. A ferromagnetic material having the formula )1 x( )x where 0.01 x 0.30.
3. A ferromagnetic material having the formula )1 x( )x Where 0.01 x 0.30.
4. A ferromagnetic material having the formula )1 X( )x where 0.01 x 0.30.
5. A ferromagnetic material having the formula where 0.01 x 0.30.
6. The method of forming a ferromagnetic material having the formula (EuO) (RS) where 0.01 x 0.30 and (RS) is a monosulfide of a rare earth element selected from the group consisting of cerium (Ce), lanthanum (La), erbium (Br), and gadolinium (Gd), praseosaid mixture dymium (Pr), neodymium (Nd), samari-um (Sm), dysprosium (Dy), terbium (Tb), holmium (Ho), thulium (Tm), and lutetium (Lu) comprising the steps of mixing europium oxide (EuO) and said monosulfide, heating to react at least a portion of said mixture to form a solid solution of said europium oxide (EuO) and said monosulfide, and rapidly cooling said mixture to room temperature.
7. The method of claim 6 comprising the further step of cooling said mixture to room temperature Within a 30 minute period.
8. The method of claim 6 comprising the further step of heating said mixture whereby a portion thereof enters into a liquid phase.
References Cited UNITED STATES PATENTS 2/1966 Matthias 252-62.51
OTHER REFERENCES Didchenko et al.: Some Electrical and Magnetic Properties of Rare Earth Monosu lfides and Nitrides, J. Phys. Chem. Solids, vol. 24, 1963, pages 863870.
TOBIAS E. LEVOW, Primary Examiner. ROBERT D. EDMONDS, Examiner.
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| US428862A US3371042A (en) | 1965-01-28 | 1965-01-28 | Ferromagnetic materials |
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| US428862A US3371042A (en) | 1965-01-28 | 1965-01-28 | Ferromagnetic materials |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3539382A (en) * | 1967-09-08 | 1970-11-10 | Ibm | Film of magneto-optical rare earth oxide including method therefor |
| US3544865A (en) * | 1968-12-20 | 1970-12-01 | Ibm | Rectifying ferromagnetic semiconductor devices and method for making same |
| US4577322A (en) * | 1983-10-19 | 1986-03-18 | General Motors Corporation | Lead-ytterbium-tin telluride heterojunction semiconductor laser |
| US4608694A (en) * | 1983-12-27 | 1986-08-26 | General Motors Corporation | Lead-europium selenide-telluride heterojunction semiconductor laser |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3234494A (en) * | 1961-07-28 | 1966-02-08 | Bell Telephone Labor Inc | Ferromagnetic compound and devices including elements thereof |
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1965
- 1965-01-28 US US428862A patent/US3371042A/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3234494A (en) * | 1961-07-28 | 1966-02-08 | Bell Telephone Labor Inc | Ferromagnetic compound and devices including elements thereof |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3539382A (en) * | 1967-09-08 | 1970-11-10 | Ibm | Film of magneto-optical rare earth oxide including method therefor |
| US3544865A (en) * | 1968-12-20 | 1970-12-01 | Ibm | Rectifying ferromagnetic semiconductor devices and method for making same |
| US4577322A (en) * | 1983-10-19 | 1986-03-18 | General Motors Corporation | Lead-ytterbium-tin telluride heterojunction semiconductor laser |
| US4608694A (en) * | 1983-12-27 | 1986-08-26 | General Motors Corporation | Lead-europium selenide-telluride heterojunction semiconductor laser |
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