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US2677663A - Manganite composition - Google Patents

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US2677663A
US2677663A US142525A US14252550A US2677663A US 2677663 A US2677663 A US 2677663A US 142525 A US142525 A US 142525A US 14252550 A US14252550 A US 14252550A US 2677663 A US2677663 A US 2677663A
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manganite
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lanthanum
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mixed crystals
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Jonker Gerard Heinrich
Jan Heinrik Van Santen
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Hartford National Bank and Trust Co
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/016—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on manganites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/32—Manganese, technetium or rhenium
    • B01J23/34—Manganese

Definitions

  • This invention relates to magnet cores and particularly to cores constituted by manganites.
  • a manganite is an oxygen compound of manganese and a second bivalent or trivalent metal. More particularly, manganites as referred to hereinafter in the specification and in the claims are compositions which have the general formulae lM Mnos and M D/Z1103 According to the invention, the magnet cores are constituted by essentially homogeneous mixed crystals of two or more of the foregoing manganites.
  • the term mixed crystal refers to the crystalline combination or two or more such manganites which are solid solutions of the manganites having a common chemical character istic. More specifically, the mixed crystal is a new chemical compound of the individual manganite having a substantially homogeneous crystalline structure.
  • the mixed crystals are preferably composed in a stoichiometric ratio of two or more manganites but it is not essential that they be in exact stoichiometric ratio, and the mixed crystals may contain a slight excess or deficiency of oxygen a slight excess or deficiency of manganese, and still be satisfactory for the purposes or" the invention.
  • the mixed crystals of the manganites may also contain additional compounds such as ferrites, c romites, titanates and aluminates, without deting from the inventive concept.
  • the mixed crystals of the manganites do not all have a purely cubic crystalline structure since ratios of the axes and the axial angles of crystal system may slightly depart from se of the cubic crystal, system.
  • lanthanum manganite In describing the invention, particular referenoe will be made to lanthanum manganite. owever, the invention is not restricted solely to toe case where lanthanum manganite is one of the constituents of the mixed crystal.
  • the purof describing the invention in connection with lanthanum manganite is that the perowskits structure of the mixed crystal requires a large ion at the position of the M in the crystal lattice which is furnished most conveniently by the lanthanum ion.
  • manganites which are suitable for the purpose of the invention and which will be described more completely in the examples to be given later, are manganites of strontium, barium and lead, and in connection with desired mag netic properties to a lesser degree, those of calcium and cadmium, even though not all of these materials, taken individually, exhibit a perowskite structure.
  • the lanthanum in lanthanum manganite may be replaced by strontium to the extent of approximately at most, and at most by 50% by barium or lead. Exceeding the limit set for the substitution by other constituents results in a crystal phase different than the perowskite phase.
  • Partially substituting another manganite for lanthanum manganite has the eiiect of varying the curie point of the mixed crystal manganite, the curie point being that temperature at which, for all practical purposes, the material exhibits no ferromagnetic properties, i. e., it is paramagnetic
  • the curie point being that temperature at which, for all practical purposes, the material exhibits no ferromagnetic properties, i. e., it is paramagnetic
  • the curie point can be raised to a temperature above 0 C. If the lanthanum is replaced by strontium, barium and/or lead, it is possible to obtain material at ambient temperatures having an initial permeability of 106 to 200 which was measured at 4 ire/sec. and a magnetic saturation of approximately 60 gauss cm. /g.
  • the mixed crystals of the manganites may be prepared by reaction of a mixture of the constituent metal oxides or compounds which decompose into these oxides upon heating, or compounds which in addition to one or more of the desired metal oxides contain only volatile components.
  • the constitution of this mixture, the reaction temperature, the partial oxygen pressure of the ambient atmosphere at the reaction temperature, and the partial oxygen pressure of the cooling atmosphere all determine the oxygen content of the mixed crystal thus formed.
  • the magnet cores according to the invention are produced by conventional techniques employed in the ceramic industry, the material being used in the form of powder during the sintering and cooling operations and the conditions being such as to prevent conversions adversely aiiecting the magnetic properties, such as the formation of undesirable second phases in the material.
  • the preparation of the desired mixed crystals and the sintering operation required for the manufacture of the magnet cores may alternatively be effected in one operation.
  • the mixed crystals in question may be fabricated into magnet cores with the use of a binder.
  • EXAMPLE I A mixture of 130 gms. of lanthanum carbonate, 29.5 gins. of strontium carbonate and 115 gms. of manganese carbonate is sintered in air at 900 to 1000 C. for several hours. After cooling, the mixture is ground and molded into the desired shape, followed by sintering in air at a temperature between 1370 and 1 150 C. for three hours.
  • the magnet core obtained consists of essentially homogeneous mixed crystals of 80 mol. percent lanthanum manganite and mol. percent strontium manganite. In a similar manner, mixed crystals of 70 mol. percent lanthanum manganite and mol. percent strontium manganite, of 60 mol. percent lanthanum manganite and mol.
  • a mixture of 130 gms. lanthanum oxide, 39.5 barium carbonate and 115 gms. manganese carbonate is sintered in air at 900 to 1000 C. for several hours. After cooling, the mixture is ground and moulded into the desired shape, followed by sintering in air at a temperature between 1370 and 1450" C. for three hours, thus obtaining a magnet core consisting of essentially homogeneous mixed crystals of mol. percent lanthanum maganite and 20 mol. percent barium manganite. In a similar manner, mixed crystals of 75 mol. percent lanthanum manganite and 25 mol. percent barium manganite, of 70 mol. percent lanthanum manganite and 30 mol. percent barium manganite and of 65 mol. percent lanthanum manganite and 35 mol. percent barium manganite are formed.
  • ccuww macro EXAMPLE III A mixture of 160 gms. lanthanum carbonate, 14.3 gms. strontium carbonate, 103.5 gms. manganese carbonate and 5.1 gms. aluminium oxide is sintered in air at 900 to 1000 C. for several hours. After cooling, the mixture is ground and moulded into the desired shape, followed by sintering in air at a temperature between 1370 and 1450" C. for three hours.
  • the magnet core obtained. may be conceived to consist of essentially homogeneous mixed crystals of 60 mol. percent lanthanum manganite, 10 mol. percent lanthanum aluminate (LaAlOs) and 30 mol. percent strontium manganite. The curie-temperature is 43 C. and the magnetic saturation l7 gauss. cm. /g. at 20 C.
  • EXAMPLE IV A mixture of 114 gms. lanthanum oxide, 4 1.3 gms. strontium carbonate, 32.6 gms. manganese eroxide and 4 gms. of ferrioxide is sintered in air at 900 to 1000 C. for several hours. After cooling, the mixture is ground and moulded into the desired shape, followed by sintering in air at a temperature between 1370 and 1450" C. for three hours.
  • the magnet core obtained may be conceived to consist of essentially homogeneous mixed crystals of 65 mol. percent lanthanum manganite, 5 mol. percent lanthanum ferrite and 30 mol. percent strontium manganite.
  • the curie-temperature is 70 C. and the magnetic saturation 39 gauss. cm. /g. at 20 C.
  • EXAMPLE V A mixture of 114 gms. lanthanum oxide, 22.1 gms. of strontium carbonate, 29.6 gms. of barium carbonate and 115 gms. manganese carbonate is sintered in air at 900 to 1000 C. for several hours. After cooling, the mixture is ground and moulded into the desired shape, followed by sintering in air for three hours at a temperature between 1370 and 1450 C.
  • the magnetic core obtained consists of essentially homogeneous mixed crystals of 70 mol. percent lanthanum manganite, 15 mol. percent strontium manganite and 15 mol. percent barium manganite, the curie temperature being 70 C., and the magnetic saturation in gauss. cmfi/g. at 20 C. being 57.
  • the initial permeability with 4 kc./sec. and at C. was found to be 180.
  • EXAMPLE VI A mixture of 114 gms. of lanthanum oxide, 80 gms. of lead carbonate and 115 gms. of maganese carbonate is sintered in air for several hours at 900 to 1000 C. After cooling, the mixture is ground and moulded into the desired shape, followed by sintering in air at a temperature gradually increasing from 1100 to 1300 C. for three hours.
  • the magnet core obtained consists of essentially homogeneous mixed crystals of 70 mol. percent lanthanum manganite and 30 mol. percent of lead manganite, the curie-temperature being 90 C. and the magnetic saturation in gauss. cm. /g. at 20 C. being 36.
  • a new composition of matter consisting essentially of homogeneous mixed crystals of a manganite having the formula M+ MnO3, M++ being a metal selected from the group consisting of strontium, barium, and lead, and a manganite having the formula M+++Mn0s, M+++ being a metal selected from the group consisting of lanthanum, praeseodymium and neodymium, said mixed crystals having a perowskite crystal structure.
  • a new composition of matter consisting of essentially homogeneous mixed crystals constituted by approximately between to 80 mol. percent of lanthanum manganite and approximately 20 to 40 mol. per cent of strontium manganite.
  • a new composition of matter consisting of essentially homogeneous mixed crystals of approximately between and 80 mol. per cent of lanthanum manganite and approximately between 20 and 35 mol. per cent of barium manganite.
  • a new composition of matter consisting of essentially homogeneous mixed crystals of 60 mol. per cent of lanthanum manganite, approximately 10 mol. per cent of lanthanum aluminate and approximately 30 mol. per cent of strontium manganite.
  • a new composition of matter consisting of essentially homogeneous mixed crystals of approximately 65 mol. per cent of lanthanum manganite, approximately 5 mol. per cent of lanthanum ferrite and approximately 30 mol. per cent of strontium manganite.
  • a new composition of matter consisting of essentially homogeneous mixed crystals of approximately mol. per cent of lanthanum manganite, approximately 15 mol. per cent of strontium manganite and approximately 15 mol. per cent of barium manganite.
  • a new composition of matter consisting of essentially homogeneous mixed crystals of approximately 70 mol. per cent of lanthanum manganite and approximately 30 mol. per cent of lead manganite.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Ceramic Engineering (AREA)
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Description

Patented May 4, 1954 UNITED STATES 2,677,663 TENT OFFICE MANGANETE COMPUSITION No Drawing. Application February 4, 1950, Serial No. 142,525
@Iaims priority, application Netherlands February 5, 1%9
11 Claims.
This invention relates to magnet cores and particularly to cores constituted by manganites.
A manganite is an oxygen compound of manganese and a second bivalent or trivalent metal. More particularly, manganites as referred to hereinafter in the specification and in the claims are compositions which have the general formulae lM Mnos and M D/Z1103 According to the invention, the magnet cores are constituted by essentially homogeneous mixed crystals of two or more of the foregoing manganites. The term mixed crystal refers to the crystalline combination or two or more such manganites which are solid solutions of the manganites having a common chemical character istic. More specifically, the mixed crystal is a new chemical compound of the individual manganite having a substantially homogeneous crystalline structure.
The mixed crystals are preferably composed in a stoichiometric ratio of two or more manganites but it is not essential that they be in exact stoichiometric ratio, and the mixed crystals may contain a slight excess or deficiency of oxygen a slight excess or deficiency of manganese, and still be satisfactory for the purposes or" the invention.
The mixed crystals of the manganites may also contain additional compounds such as ferrites, c romites, titanates and aluminates, without deting from the inventive concept.
The mixed crystals of the manganites do not all have a purely cubic crystalline structure since ratios of the axes and the axial angles of crystal system may slightly depart from se of the cubic crystal, system.
In describing the invention, particular referenoe will be made to lanthanum manganite. owever, the invention is not restricted solely to toe case where lanthanum manganite is one of the constituents of the mixed crystal. The purof describing the invention in connection with lanthanum manganite is that the perowskits structure of the mixed crystal requires a large ion at the position of the M in the crystal lattice which is furnished most conveniently by the lanthanum ion.
this connection it is to be noted that there other manganites which may have no perow- 2 praseodymium manganite and neodymium manganite.
Other manganites which are suitable for the purpose of the invention and which will be described more completely in the examples to be given later, are manganites of strontium, barium and lead, and in connection with desired mag netic properties to a lesser degree, those of calcium and cadmium, even though not all of these materials, taken individually, exhibit a perowskite structure.
However, in determining the formation of crystals having a perowskite structure, there is a definite limit for the replacement of the lanthanum in lanthanum manganite. For example, the lanthanum in lanthanum manganite may be replaced by strontium to the extent of approximately at most, and at most by 50% by barium or lead. Exceeding the limit set for the substitution by other constituents results in a crystal phase different than the perowskite phase.
Partially substituting another manganite for lanthanum manganite has the eiiect of varying the curie point of the mixed crystal manganite, the curie point being that temperature at which, for all practical purposes, the material exhibits no ferromagnetic properties, i. e., it is paramagnetic By replacing some of the lanthanum manie in the mixed crystal with strontium, barium and/or lead manganite, a curie point exceeding room temperature can be readily ob- Mixed crystals including 25 to 50 mol. per cent of strontium, barium, or lead manganite,
" respectively, and containing '75 to 49 mol. per cent of lanthanum manganite, has a curie point between 6:? and 99 C., which is above normal ambient temperatures, in which event these materials are suitable for magnet cores.
In this connection it is to be noted that various mixed crystals of manganites exhibit a curie point which is below 0 C. and consequently such materials have no ferromagnetic properties at normal ambient temperatures. A comparatively pure lanthanum manganite containing 4% of manganese which is tetravalent, has a curie point below -200 C. If the perowskite structure is retained and no second phase exists in the material, the said material may contain more than 25% manganese in tetravalent form, so that a material of the formula LaMnO3 1e5 may, for e 'nple, be obtained having a curie point in the neighbourhood of 20 C. By partly replacing the lanthanum in the lanthanum manganite by one of the bivalent metals, the curie point can be raised to a temperature above 0 C. If the lanthanum is replaced by strontium, barium and/or lead, it is possible to obtain material at ambient temperatures having an initial permeability of 106 to 200 which was measured at 4 ire/sec. and a magnetic saturation of approximately 60 gauss cm. /g.
Substitution of Al, Cr, Ti, Fe, Co or Ni, for example, for part of the Mn, generally involves a lower curie temperature. For this reason only a limited substitution of these metals is desirable.
The mixed crystals of the manganites may be prepared by reaction of a mixture of the constituent metal oxides or compounds which decompose into these oxides upon heating, or compounds which in addition to one or more of the desired metal oxides contain only volatile components. The constitution of this mixture, the reaction temperature, the partial oxygen pressure of the ambient atmosphere at the reaction temperature, and the partial oxygen pressure of the cooling atmosphere all determine the oxygen content of the mixed crystal thus formed.
The magnet cores according to the invention are produced by conventional techniques employed in the ceramic industry, the material being used in the form of powder during the sintering and cooling operations and the conditions being such as to prevent conversions adversely aiiecting the magnetic properties, such as the formation of undesirable second phases in the material. After shaping the initial mixture, the preparation of the desired mixed crystals and the sintering operation required for the manufacture of the magnet cores may alternatively be effected in one operation. Finally, the mixed crystals in question may be fabricated into magnet cores with the use of a binder.
The invention will be described in connection with the following examples which indicate several preferred embodiments of the invention.
EXAMPLE I A mixture of 130 gms. of lanthanum carbonate, 29.5 gins. of strontium carbonate and 115 gms. of manganese carbonate is sintered in air at 900 to 1000 C. for several hours. After cooling, the mixture is ground and molded into the desired shape, followed by sintering in air at a temperature between 1370 and 1 150 C. for three hours. The magnet core obtained consists of essentially homogeneous mixed crystals of 80 mol. percent lanthanum manganite and mol. percent strontium manganite. In a similar manner, mixed crystals of 70 mol. percent lanthanum manganite and mol. percent strontium manganite, of 60 mol. percent lanthanum manganite and mol. percent strontium manganite and of mol. percent lanthanum manganite and 50 mol. percent strontium manganite are produced. If the composition contains more than 40 mol. percent of M MnOs, it is desirable to use an atmosphere having a higher partial pressure of the oxygen or even pure oxygen. Several magnetic properties are stated in the following table.
A mixture of 130 gms. lanthanum oxide, 39.5 barium carbonate and 115 gms. manganese carbonate is sintered in air at 900 to 1000 C. for several hours. After cooling, the mixture is ground and moulded into the desired shape, followed by sintering in air at a temperature between 1370 and 1450" C. for three hours, thus obtaining a magnet core consisting of essentially homogeneous mixed crystals of mol. percent lanthanum maganite and 20 mol. percent barium manganite. In a similar manner, mixed crystals of 75 mol. percent lanthanum manganite and 25 mol. percent barium manganite, of 70 mol. percent lanthanum manganite and 30 mol. percent barium manganite and of 65 mol. percent lanthanum manganite and 35 mol. percent barium manganite are formed. Several properties are stated in the following table.
ccuww macro EXAMPLE III A mixture of 160 gms. lanthanum carbonate, 14.3 gms. strontium carbonate, 103.5 gms. manganese carbonate and 5.1 gms. aluminium oxide is sintered in air at 900 to 1000 C. for several hours. After cooling, the mixture is ground and moulded into the desired shape, followed by sintering in air at a temperature between 1370 and 1450" C. for three hours. The magnet core obtained. may be conceived to consist of essentially homogeneous mixed crystals of 60 mol. percent lanthanum manganite, 10 mol. percent lanthanum aluminate (LaAlOs) and 30 mol. percent strontium manganite. The curie-temperature is 43 C. and the magnetic saturation l7 gauss. cm. /g. at 20 C.
EXAMPLE IV A mixture of 114 gms. lanthanum oxide, 4 1.3 gms. strontium carbonate, 32.6 gms. manganese eroxide and 4 gms. of ferrioxide is sintered in air at 900 to 1000 C. for several hours. After cooling, the mixture is ground and moulded into the desired shape, followed by sintering in air at a temperature between 1370 and 1450" C. for three hours. The magnet core obtained may be conceived to consist of essentially homogeneous mixed crystals of 65 mol. percent lanthanum manganite, 5 mol. percent lanthanum ferrite and 30 mol. percent strontium manganite. The curie-temperature is 70 C. and the magnetic saturation 39 gauss. cm. /g. at 20 C.
EXAMPLE V A mixture of 114 gms. lanthanum oxide, 22.1 gms. of strontium carbonate, 29.6 gms. of barium carbonate and 115 gms. manganese carbonate is sintered in air at 900 to 1000 C. for several hours. After cooling, the mixture is ground and moulded into the desired shape, followed by sintering in air for three hours at a temperature between 1370 and 1450 C. The magnetic core obtained consists of essentially homogeneous mixed crystals of 70 mol. percent lanthanum manganite, 15 mol. percent strontium manganite and 15 mol. percent barium manganite, the curie temperature being 70 C., and the magnetic saturation in gauss. cmfi/g. at 20 C. being 57. The initial permeability with 4 kc./sec. and at C. was found to be 180.
EXAMPLE VI A mixture of 114 gms. of lanthanum oxide, 80 gms. of lead carbonate and 115 gms. of maganese carbonate is sintered in air for several hours at 900 to 1000 C. After cooling, the mixture is ground and moulded into the desired shape, followed by sintering in air at a temperature gradually increasing from 1100 to 1300 C. for three hours. The magnet core obtained consists of essentially homogeneous mixed crystals of 70 mol. percent lanthanum manganite and 30 mol. percent of lead manganite, the curie-temperature being 90 C. and the magnetic saturation in gauss. cm. /g. at 20 C. being 36.
While we have thus far described our invention with specific examples and methods of preparation, other modifications thereof will be obvious to those skilled in the art without departing from the spirit and scope of the invention.
What we claim is.
1. A new composition of matter consisting essentially of homogeneous mixed crystals of a manganite having the formula M+ MnO3, M++ being a metal selected from the group consisting of strontium, barium, and lead, and a manganite having the formula M+++Mn0s, M+++ being a metal selected from the group consisting of lanthanum, praeseodymium and neodymium, said mixed crystals having a perowskite crystal structure.
2. A new composition of matter as claimed in claim 1 in which the mixed crystals include a material selected from the group consisting of a ferrite and an aluminate.
3. A new composition of matter as claimed in claim 1, in which the mixed crystals contain approximately between to 50 mol. percent of a mangani'te selected from the group consisting of strontium manganite, barium manganite and lead manganite, and approximately 75 to 50 mol. percent of lanthanum manganite.
4. A new composition of matter as claimed in claim 1, in which the mixed crystals include a ferrite.
5. A new composition of matter as claimed in claim 1, in which the mixed crystals include an aluminate.
6. A new composition of matter consisting of essentially homogeneous mixed crystals constituted by approximately between to 80 mol. percent of lanthanum manganite and approximately 20 to 40 mol. per cent of strontium manganite.
'7. A new composition of matter consisting of essentially homogeneous mixed crystals of approximately between and 80 mol. per cent of lanthanum manganite and approximately between 20 and 35 mol. per cent of barium manganite.
8. A new composition of matter consisting of essentially homogeneous mixed crystals of 60 mol. per cent of lanthanum manganite, approximately 10 mol. per cent of lanthanum aluminate and approximately 30 mol. per cent of strontium manganite.
9. A new composition of matter consisting of essentially homogeneous mixed crystals of approximately 65 mol. per cent of lanthanum manganite, approximately 5 mol. per cent of lanthanum ferrite and approximately 30 mol. per cent of strontium manganite.
10. A new composition of matter consisting of essentially homogeneous mixed crystals of approximately mol. per cent of lanthanum manganite, approximately 15 mol. per cent of strontium manganite and approximately 15 mol. per cent of barium manganite.
11. A new composition of matter consisting of essentially homogeneous mixed crystals of approximately 70 mol. per cent of lanthanum manganite and approximately 30 mol. per cent of lead manganite.
References Cited in the file of this patent UNITED STATES PATENTS Number

Claims (1)

10. A NEW COMPOSITON OF MATTER CONSISTING OF ESSENTIALLY HOMOGENEOUS MIXED CRYSTALS OF APPROXIMATELY 70 MOL. PER CENT OF LANTHANUM MANGANITE, APPROXIMATELY 15 MOL. PER CENT OF STRONTIUM MANGANITE AND APPROXIMATELY 15 MOL. PER CENT OF BARIUM MANGANITE.
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Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2770523A (en) * 1954-08-26 1956-11-13 Du Pont Ferro-magnetic cobalt and nickel manganese oxides having the ilmenite-type crystal structure
US2938183A (en) * 1956-11-09 1960-05-24 Bell Telephone Labor Inc Single crystal inductor core of magnetizable garnet
US2943913A (en) * 1957-09-17 1960-07-05 Du Pont Ferromagnetic material and process
US2954346A (en) * 1959-10-28 1960-09-27 Ibm Permanent magnetic materials
US2957827A (en) * 1957-04-30 1960-10-25 Bell Telephone Labor Inc Method of making single crystal garnets
US2964793A (en) * 1957-11-13 1960-12-20 Leyman Corp Method of making permanent magnets
US2972176A (en) * 1956-02-15 1961-02-21 Clevite Corp Prestressed dielectric ceramic bodies
US2977312A (en) * 1956-05-16 1961-03-28 Philips Corp Ferromagnetic material
US2980617A (en) * 1956-03-13 1961-04-18 Indiana General Corp Ferrite compositions and method of making same
US2982607A (en) * 1958-11-06 1961-05-02 Ibm Lanthanum manganese hexaferrites
US3027327A (en) * 1957-10-08 1962-03-27 Gen Electric Preparation of ferromagnetic ferrite materials
US3034987A (en) * 1957-12-31 1962-05-15 Rca Corp Magnetic cores
US3066102A (en) * 1957-12-19 1962-11-27 Steatit Magnesia Ag Ferrite containing neodymium
US3214389A (en) * 1960-09-29 1965-10-26 Du Pont Method of preparing a mangano-chromia-manganite catalyst composition
US3380919A (en) * 1964-02-06 1968-04-30 Ampex Preparation of ferromagnetic nimno
US5068050A (en) * 1987-11-18 1991-11-26 Kabushiki Kaisha Toshiba Amorphous oxide magnetic material

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1840789A (en) * 1926-12-10 1932-01-12 Communications Patents Inc Cathode for thermionic devices

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1840789A (en) * 1926-12-10 1932-01-12 Communications Patents Inc Cathode for thermionic devices

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2770523A (en) * 1954-08-26 1956-11-13 Du Pont Ferro-magnetic cobalt and nickel manganese oxides having the ilmenite-type crystal structure
US2972176A (en) * 1956-02-15 1961-02-21 Clevite Corp Prestressed dielectric ceramic bodies
US2980617A (en) * 1956-03-13 1961-04-18 Indiana General Corp Ferrite compositions and method of making same
US2977312A (en) * 1956-05-16 1961-03-28 Philips Corp Ferromagnetic material
US2938183A (en) * 1956-11-09 1960-05-24 Bell Telephone Labor Inc Single crystal inductor core of magnetizable garnet
US2957827A (en) * 1957-04-30 1960-10-25 Bell Telephone Labor Inc Method of making single crystal garnets
US2943913A (en) * 1957-09-17 1960-07-05 Du Pont Ferromagnetic material and process
US3027327A (en) * 1957-10-08 1962-03-27 Gen Electric Preparation of ferromagnetic ferrite materials
US2964793A (en) * 1957-11-13 1960-12-20 Leyman Corp Method of making permanent magnets
US3066102A (en) * 1957-12-19 1962-11-27 Steatit Magnesia Ag Ferrite containing neodymium
US3034987A (en) * 1957-12-31 1962-05-15 Rca Corp Magnetic cores
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US2954346A (en) * 1959-10-28 1960-09-27 Ibm Permanent magnetic materials
US3214389A (en) * 1960-09-29 1965-10-26 Du Pont Method of preparing a mangano-chromia-manganite catalyst composition
US3380919A (en) * 1964-02-06 1968-04-30 Ampex Preparation of ferromagnetic nimno
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