Patent EP0039773A1 successfully refreshed from Google Patents.
EP0039773A1
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Method of producing barium-ferrite series powder
Assignee: Toshiba Corp
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Filing: 1981-03-31
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Granted: —
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Expires: 2001-03-31
Abstract
Abstract Barium-ferrite series powders are prepared from an alkaline aqueous solution containing a prescribed ratio of ions of the metals equal to those contained in the powder. In the first stage, the alkaline aqueous solution is heated at a constant volume at 150 to 300°C to precipitate a precursor of the barium-ferrite series powder. Then, the precursor is baked at 700 to 1,000°C to crystallize the precursor.
Inventors
- 👤 Hiroshi Endo
- 👤 Masashi Awa
- 👤 Shigeo Iiri
- 👤 Toshihiko Oguchi
- 👤 Isao Suzuki
- 👤 Naoyuki Hirate
- 👤 Masaru Hayashi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 17:22
CPC Classifications
C; C01; C01G; C01G49/00; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/10; H01F1/11; C01G49/0018; C01G49/0036; C01G49/0063; C01G49/0072; C01G49/009; C04; C04B; C04B35/00; C04B35/01; C04B35/26; C04B35/2683; C01P; C01P2002/00; C01P2002/50; C01P2002/52; C01P2004/00; C01P2004/01; C01P2004/03; C01P2004/20; C01P2004/22; C01P2004/51; C01P2004/54; C01P2004/60; C01P2004/62; C01P2006/00; C01P2006/42
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
131 words
A method of producing barium-ferrite series powders from an alkaline aqueous solution containing metal ions in amounts sufficient to provide the metals contained in the final product of the barium-ferrite series powder, characterized in that the barium-ferrite series powder has a general formula of, BaO·n(Fel-mMm) 2 O 3 , where "M" is at least one substituent selected from the group consisting of Co, Ti, Ni, Mn, Cu, Zn, In, Ge and Nb, "m" is 0 to 0.2, and "n" is 5.4 to 6.0; the alkaline aqueous solution has an alkaline normality of at least 0.01 N; the alkaline aqueous solution is heated at 150 to 300°C at constant volume to precipitate a precursor of the barium-ferrite series powder; and the precursor is baked at 700 to 1,000°C to crystallize the precursor.
Claim 2
Independent Claim
131 words
A method of producing barium-ferrite series powders from an alkaline aqueous solution containing metal ions in amounts sufficient to provide the metals contained in the final product of the barium-ferrite series powder, characterized in that the barium-ferrite series powder has a general formula of, BaO·n(Fel-mMm) 2 O 3 , where "M" is at least one substituent selected from the group consisting of Co, Ti, Ni, Mn, Cu, Zn, In, Ge and Nb, "m" is 0 to 0.2, and "n" is 5.4 to 6.0; the alkaline aqueous solution has an alkaline normality of at least 0.01 N; the alkaline aqueous solution is heated at 150 to 300°C at constant volume to precipitate a precursor of the barium-ferrite series powder; and the precursor is baked at 700 to 1,000°C to crystallize the precursor.
Claim 3
Dependent Claim
33 words
The method according to claim 1, wherein the barium ions, iron (III) ions and ions of the substituent component M are provided by water-soluble compounds of barium, iron (III) and substituent component M.
Claim 4
Dependent Claim
25 words
The method according to claim 2, wherein the water-soluble compounds are selected from the group consisting of nitrates, perchlorates, chlorates, chlorides, fluorides, acetates and sulfates.
Claim 5
Dependent Claim
19 words
The method according to claim 1, wherein the alkalinity of the aqueous solution is provided by a strong alkali.
Claim 6
Dependent Claim
24 words
The method according to claim 4, wherein the strong alkali is selected from the group consisting of sodium hydroxide, potassium hydroxide and lithium hydroxide.
Claim 7
Dependent Claim
50 words
The method according to claim 2, wherein the alkaline aqueous solution is prepared by adding a first aqueous solution to a second aqueous solution of the strong alkali, said first solution being prepared in advance by dissolving the water-soluble compounds of barium, iron (III) and substituent component M in water.
Claim 8
Dependent Claim
28 words
The method according to claim 6, wherein the first aqueous solution is cooled to 20°C or less and, then, added to the aqueous solution of the strong alkali.
Claim 9
Dependent Claim
24 words
The method according to claim 4, 6 or 7, wherein the alkaline aqueous solution contains 1 to 6 N of the strong alkaline compound.
Claim 10
Dependent Claim
15 words
The method according to claim 8, wherein the normality N ranges between 3 and 6.
Claim 11
Dependent Claim
23 words
The method according to claim 1, wherein the heating temperature in the first stage falls within the range of between 180°C and 250°C.
Claim 12
Dependent Claim
22 words
The method according to claim 1 or 10, wherein the alkaline aqueous solution is heated in the first stage in an autoclave.
Claim 13
Dependent Claim
23 words
The method according to claim 1, wherein the baking temperature in the second stage falls within the range of between 850°C and 950°C.
Claim 14
Dependent Claim
19 words
The method according to claim 1 or 12, wherein the precursor particles are kept floated in the baking step.
Claim 15
Dependent Claim
22 words
The method according to claim 13, wherein the precursor is baked in a rotary kiln or baking furnace of fluidized bed type.
References Cited (Backward Citations)
GB908218A
Cited
US4025449A
Cited
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