Dowa Electronics Materials Co., Ltd.

Nichia Corporation

Mitsubishi Chemical Corporation

Dowa Mining Co., Ltd.

The University of Tokyo

Citizen Electronics Co., Ltd.

Dowa Holdings Co., Ltd.

Kenji Sakane

Akira Nagatomi

Masahiro Gotoh

Shuji Yamashita

Tetsuya Kawahito

Shin-ichi Ohkoshi

Tetsuya Ikuta

Asuka Namai

Tomoya Yamada

Kazuhiro Yamaga

Toshihiko Ueyama

Hiroko Tokoro

Marie Yoshikiyo

Yasuto Miyamoto

Yuki Mineyama

Masahiro Goth

A raw material solution containing trivalent iron ions, or trivalent iron ions and ions of a metal element that partially substitutes Fe sites, and an alkaline aqueous solution for neutralizing the raw material solution are added to a reaction system to adjust the pH of the reaction system from 1.0 to 3.0 or lower. Hydroxycarboxylic acid is added to the obtained reaction solution and the pH of the reaction system is then neutralized from 7.0 to 10.0 or lower. The obtained precipitate of a substituent metal element-containing iron oxyhydroxide is coated with silicon oxide, followed by heating so as to form particles of ε-iron oxide in which Fe sites are partially substituted by other metal elements, and then, a slurry containing the particles is classified. The iron-based oxide magnetic powder has a particle shape close to a perfect sphere and is suitable for use in a magnetic recording medium.

Iron-based oxide magnetic powder and method for producing same

[Problem] To provide a method for producing iron based oxide magnetic powder that has a narrow particle size distribution and a small content of fine particles that do not contribute to the magnetic recording characteristics, and consequently has a narrow coercive force distribution and is suitable for the enhancement of the recording density of the magnetic recording medium. [Solution] &#x3b5;-Type iron based oxide magnetic powder is obtained by a wet method, then a tetraalkylammonium salt as a surface modifier is added to a slurry containing the magnetic powder to make a concentration of 0.009 mol/kg or more and 1.0 mol/kg or less, and simultaneously to make pH of 11 or more and 14 or less, and the slurry is subjected to a dispersion treatment and then classified, so as to provide iron based oxide magnetic powder having a narrow particle size distribution and a narrow coercive force distribution.

Iron based oxide magnetic powder and method for producing same

An object of the present invention is to provide a magnetic powder having a narrow particle size distribution of epsilon-type iron oxide particles, and another object is to provide magnetic powder suitable for magnetic recording medium by improving particle size distribution, and provide epsilon-type iron oxide magnetic particles and related technologies in which a number average particle diameter of major diameters (D) is 10 to 20 nm, a 90% cumulative particle diameter (D) is 30 nm or less, and a geometric standard deviation (&#x3c3;) of major diameters is 1.45 or less, which are obtained by TEM observation.

Epsilon-type iron oxide magnetic particles and method for producing the same, magnetic powder, magnetic coating material and magnetic recording medium containing magnetic particles

A surface-modified iron-based oxide magnetic particle powder has good solid-liquid separation property in the production process, has good dispersibility in a coating material for forming a coating-type magnetic recording medium, has good orientation property, and has a small elution amount of a water-soluble alkali metal, and to provide a method for producing the surface-modified iron-based oxide magnetic particle powder. The surface-modified iron-based oxide magnetic particle powder can be obtained by neutralizing a solution containing dissolved therein a trivalent iron ion and an ion of the metal, by which the part of Fe sites is to be substituted, with an alkali aqueous solution, so as to provide a precursor, coating a silicon oxide on the precursor, heating the precursor to provide e-type iron-based oxide magnetic powder, and adhering a hydroxide or a hydrous oxide of one kind or two kinds of Al and Y thereto.

Surface-modified iron-based oxide magnetic particle powder

A method for making iron-based oxide magnetic particle powders having particular peak intensity and diffraction intensities, comprising neutralizing an aqueous solution containing a trivalent iron ion, alone or with a substituting metal (M), a step of adding hydroxycarboxylic acid to the neutralized solution to create a second solution including the hydroxycarboxylic acid D, another neutralizing step for the second solution, a coating step of silicon oxide coating iron oxyhydroxide with or without the substituted metal element found in the second neutralized solution, and heating the coated iron oxyhydroxide with or without the substituted metal element to form a silicon oxide coated iron oxide with or without the substituted metal element. After the second neutralization step, there is no water washing. As a result, the molar ratio D/(Fe+M) is between 0.125 and 1.0 and the silicon oxide coating can be uniform and the formation reaction of the hydroxide is not retarded.

Method for producing iron-based oxide magnetic particle powder

An iron-based oxide magnetic particle powder has a narrow particle size distribution a small content of fine particles that do not contribute to magnetic recording characteristics, and a narrow coercive force distribution, to enhance magnetic recording medium density. Neutralizing an aqueous solution containing a trivalent iron ion and an ion of the metal substituting a part of the Fe sites by adding an alkali to make pH of 1.5 or more and 2.5 or less, adding a hydroxycarboxylic acid, and further neutralizing by adding an alkali to make pH of 8.0 or more and 9.0 or less are performed at 5&#xb0; C. or more and 25&#xb0; C. or less. A formed iron oxyhydroxide precipitate containing the substituting metal element is rinsed with water, then coated with silicon oxide, and then heated thereby providing e-type iron-based oxide magnetic particle powder. The rinsed precipitate may be subjected to a hydrothermal treatment.

Iron-based oxide magnetic particle powder, method for producing same, coating material, and magnetic recording medium

An e-type iron-based oxide magnetic particle powder has narrow particle size distribution and has a low content of fine particles which do not contribute to magnetic recording characteristics. As a result, a narrow coercive force distribution is achieved and the powder is suitable for increasing recording density of a magnetic recording medium. The powder containing substituting metal elements can be obtained by: adding an alkali to an aqueous solution containing trivalent iron ions and ions of the metals for partially substituting Fe sites to neutralize the aqueous solution to a pH of 1.5 to 2.5; then adding a hydroxycarboxylic acid; further adding the alkali to neutralize the aqueous solution to a pH of 8.0 to 9.0; washing with water a precipitation of an iron oxyhydroxide containing the substituting metal elements produced; and coating the iron oxyhydroxide containing the substituting metal elements with a silicon oxide and heating the resultant.

Iron-based oxide magnetic particle powder and method for producing iron-based oxide magnetic particle powder

To reduce impurity contents of carbon and oxygen not contributing to light emission, then suppress deterioration of emission intensity of a phosphor, and improve emission efficiency of this phosphor. Therefore, there is provided a firing method of nitride or oxynitride phosphors, wherein a cruciblemade of nitride is used as a firing container, and firing is performed, with this crucible covered with a lid (container), to manufacture the phosphor. The phosphor is expressed by a general composition formula MABON:Z in which element M is one or more kinds of elements having bivalent valency, element A is one or more kinds of elements having tervalent valency, element B is one or more kinds of elements having tetravalent valency, O is oxygen, N is nitrogen, and element Z is an activating agent, satisfying o&#x2267;0.

Manufacturing method of nitride phosphor or oxynitride phosphor

A phosphor, which has less reduction in emission efficiency and is capable of keeping high luminance even when density of an electron beam for exciting the phosphor increases, is provided. As raw materials, CaN(2N), AlN (3N), SiN(3N), and EuO(3N) are prepared, and each of the raw materials is weighed so that a mole ratio of each element is, for example, (Ca+Eu):Al:Si=1:1:1, and mixed, then the mixture is held and fired at 1500&#xb0; C. under the inert atmosphere for three hours, and thereafter ground to produce a phosphor having a composition formula of CaSiAlN:Eu.

Phosphor for electron beam excitation and color display device using the same

To provide a phosphor having a broad emission spectrum with a peak in the range from yellow color to red color (wavelength from 570 nm to 620 nm), having a flat excitation band with large area on the long wavelength side from near ultraviolet/ultraviolet to green color (wavelength from 250 nm to 550 nm), and excellent in emission intensity and luminance, and a method of manufacturing the same, and also a light source such as white LED using the phosphor. As raw materials, CaN(2N), AlN(3N), SiN(3N), and EuO(3N) are prepared, and out of each raw material, 0.950/3 mol of CaN, 2 mol of AlN, 4/3 mol of SiN, and 0.050/2 mol of EuOare weighed, and the raw materials thus weighed are mixed by using a mortar. The raw materials thus mixed are put in a BN crucible, and retained/fired for 3 hours at 1700&#xb0; C. in a nitrogen atmosphere, and thereafter cooled from 1700&#xb0; C. to 200&#xb0; C., to thereby obtain the phosphor expressed by a composition formulaCaAlSiON:Eu.

Phosphor and manufacturing method therefore, and light source using the phosphor

A phosphor including a main production phase of a phosphor expressed by a composition formula of MmAaBbOoNn:Zz (where an element M is one or more bivalent elements, an element A is one or more trivalent elements, an element B is one or more tetravalent elements, O is oxygen, N is nitrogen, an element Z is an activator, n=2/3m+a+4/3b&#x2212;2/3o, m/(a+b)&#x2267;1/2, (o+n)/(a+b)&#x3e;4/3, wherein m=a=b=1 and o and n is not 0). A phosphor including 24 wt % to 30 wt % of Ca (calcium), 17 wt % to 21 wt % of Al (aluminum), 18 wt % to 22 wt % of Si (silicon), 1 wt % to 15 wt % of oxygen, 15 wt % to 33 wt % of nitrogen and 0.01 wt % to 10 wt % of Eu (europium), wherein an emission maximum in an emission spectrum is in a range of 600 nm to 660 nm; and wherein color chromaticity x of light emission is in a range of 0.5 to 0.7, and color chromaticity y of the light emission is in a range of 0.3 to 0.5.

Phosphor and production method of the same, method of shifting emission wavelength of phosphor, and light source and LED

To provide a phosphor for manufacturing an one chip type LED illumination, etc, by combining a near ultraviolet/ultraviolet LED and a blue LED, and having an excellent emission efficiency including luminance. The phosphor is given as a general composition formula expressed by MmAaBbOoNn:Z, (where element M is one or more kinds of elements having bivalent valency, element A is one or more kinds of elements having tervalent valency, element B is one or more kinds of elements having tetravalent valency, O is oxygen, N is nitrogen, and element Z is one or more kinds of elements acting as an activator.), satisfying a=(1+x)&#xd7;m, b=(4&#x2212;x)&#xd7;m, o=x&#xd7;m, n=(7&#x2212;x)&#xd7;m, 0&#x2266;x&#x2266;1, wherein when excited by light in a wavelength range from 300 nm to 500 nm, the phosphor has an emission spectrum with a peak wavelength in a range from 500 nm to 620 nm.

Phosphor and manufacturing method therefore, and light emission device using the phosphor

A phosphor having an excitation band relative to lights in the wide range of wavelengths from ultraviolet to visible light, and having an emission spectrum in the red range and so on, with a wide half value width, and an LED and a light source using the phosphor and emitting white and other color lights with good color rendering properties are provided. Powdered raw materials of CaN(2N), CaO (2N), AlN (3N), SiN(3N), and EuO(3N) are prepared, and the respective raw materials are mixed to have a mole ratio of the respective elements of Ca:Al:Si:Eu=0.985:1:1:0.015. The mixed raw materials are fired at 1000&#xb0; C. or higher in an inert atmosphere for three hours, and thereafter pulverized to obtain a phosphor having a composition of CaAlSiNO:Eu, which is one example of the phosphor satisfying the above described object. Furthermore, by combining the phosphor with an appropriate LED or a light source emitting from ultraviolet light to visible light, the LED and the light source emitting white and other color lights with good color rendering properties can be obtained.

Light source having phosphor including divalent, trivalent and tetravalent elements

To provide a phosphor for an electron beam excitation with a small deterioration in an emission efficiency and capable of maintaining a high luminance, even when an excitation density of an electron beam for a phosphor excitation is increased. As raw materials, CaN(2N), AlN(3N), SiN(3N), and EuO(3N) are prepared, and the raw materials thus prepared are measured and mixed, so that a molar ratio of each element becomes (Ca+Eu):Al:Si=1:1:1. Then, the mixture thus obtained is maintained and fired for at 1500&#xb0; C. for 3 hours, and thereafter crushed, to manufacture the phosphor having a composition formula CaSiAlN:Eu.

Phosphor and phosphor film for electron beam excitation and color display apparatus using the same

To provide a phosphor having an emission spectrum with a broad peak in a range from green color to yellow color, having a broad and flat excitation band capable of using lights of broad range from near ultraviolet/ultraviolet to blue lights as excitation lights, and having excellent emission efficiency and luminance. The problem is solved by providing the phosphor expressed by a general composition formula MmAaBbOoNn:Z (where element M is one or more kinds of elements having bivalent valency, element A is one or more kinds of elements having tervalent valency, element B is one or more kinds of elements having tetravalent valency, O is oxygen, N is nitrogen, and element Z is one or more kinds of elements acting as the activator), satisfying 4.0&#x3c;(a+b)/m&#x3c;7.0, a/m&#x2267;0.5, b/a&#x3e;2.5, n&#x3e;o, n=2/3m+a+4/3b&#x2212;2/3o, and having an emission spectrum with a peak wavelength of 500 nm to 650 nm when excited by light in a wavelength range from 300 nm to 500 nm.

Growing community of inventors

Tokyo, Japan

Kenji Sakane