Abstract: There is provided an oriented body containing platinum group-substituted-6 iron oxide particles typified by Rh-substituted ?-iron oxide or Ru-substituted ?-iron oxide applicable to MAMR, MIMR, or F-MIMR system, and a technique related thereto, containing platinum group element-substituted ?-iron oxide particles in which a part of ?-iron oxide is substituted with at least one element of platinum group elements, as magnetic particles wherein the degree of orientation of the magnetic particles defined by the degree of orientation=SQ (direction of magnetization easy-axes)/SQ (direction of magnetization hard-axes) exceeds 5.0, and a coercive force exceeds 31 kOe.

Abstract: An epsilon iron oxide has an average particle size of 10 to 18 nm, a part of the iron element being substituted with a substitutional element and has a coercive force of 14 kOe or less, wherein a coefficient of variation of the particle size is 40% or less. A method for producing the same, a magnetic coating material and a magnetic recording medium using the epsilon iron oxide, includes depositing a metal compound of a substitutional element on iron oxide hydroxide to thereby obtain iron oxide hydroxide on which the metal compound is deposited; coating the iron oxide hydroxide on which the metal compound is deposited, with silicon oxide to thereby obtain iron oxide hydroxide coated with the silicon oxide; and applying heat treatment to the silicon oxide-coated iron oxide hydroxide in an oxidizing atmosphere, wherein a part of an iron element is substituted with the substitutional element.

Abstract: There are provided an oriented body such as a magnetic sheet in which a value of degree of orientation of magnetic particles is beyond 3.5, and a method for producing the same, and a device for producing the same, wherein the oriented body such as a magnetic sheet is produced through the steps of: mixing a mixed solution containing a solvent and a vehicle and ?-iron oxide particles by shaking stirring, and dispersing the ?-iron oxide particles in the mixed solution; providing a mixed solution in which the ?-iron oxide particles are dispersed, on a predetermined substrate; and removing the solvent while applying a magnetic field to the substrate provided with the mixed solution, to obtain an oriented body.

Abstract: There is provided a magnetic substance containing substituted ?-iron oxide particles applicable as a magnetic toner of one-component development system, and a technique related thereto, which is the magnetic substance containing substituted ?-iron oxide particles in which a part of ?-iron oxide is substituted with a metal element other than iron, and satisfying at least one of the following conditions: (Condition 1) A molar extinction coefficient of a magnetic substance dispersion liquid at a wavelength of 450 nm is less than 770 dm3 mol?1 cm?1. (Condition 2) A molar extinction coefficient of the magnetic substance dispersion liquid at a wavelength of 500 nm is less than 430 dm3 mol?1 cm?1.

Abstract: There is provided an oriented body containing platinum group-substituted-6 iron oxide particles typified by Rh-substituted ?-iron oxide or Ru-substituted ?-iron oxide applicable to MAMR, MIMR, or F-MIMR system, and a technique related thereto, containing platinum group element-substituted ?-iron oxide particles in which a part of ?-iron oxide is substituted with at least one element of platinum group elements, as magnetic particles wherein the degree of orientation of the magnetic particles defined by the degree of orientation=SQ (direction of magnetization easy-axes)/SQ (direction of magnetization hard-axes) exceeds 5.0, and a coercive force exceeds 31 kOe.

Abstract: An epsilon iron oxide has an average particle size of 10 to 18 nm, a part of the iron element being substituted with a substitutional element and has a coercive force of 14 kOe or less, wherein a coefficient of variation of the particle size is 40% or less. A method for producing the same, a magnetic coating material and a magnetic recording medium using the epsilon iron oxide, includes depositing a metal compound of a substitutional element on iron oxide hydroxide to thereby obtain iron oxide hydroxide on which the metal compound is deposited; coating the iron oxide hydroxide on which the metal compound is deposited, with silicon oxide to thereby obtain iron oxide hydroxide coated with the silicon oxide; and applying heat treatment to the silicon oxide-coated iron oxide hydroxide in an oxidizing atmosphere, wherein a part of an iron element is substituted with the substitutional element.

Abstract: There are provided an oriented body such as a magnetic sheet in which a value of degree of orientation of magnetic particles is beyond 3.5, and a method for producing the same, and a device for producing the same, wherein the oriented body such as a magnetic sheet is produced through the steps of: mixing a mixed solution containing a solvent and a vehicle and ?-iron oxide particles by shaking stirring, and dispersing the ?-iron oxide particles in the mixed solution; providing a mixed solution in which the ?-iron oxide particles are dispersed, on a predetermined substrate; and removing the solvent while applying a magnetic field to the substrate provided with the mixed solution, to obtain an oriented body.

Abstract: Provided is magnetic powder capable of enhancing simultaneously both magnetic characteristics including SNP and durability of a magnetic recording medium. The hexagonal ferrite magnetic powder for a magnetic recording medium has a Ba/Fe molar ratio of 8.0% or more, a Bi/Fe molar ratio of 2.5% or more and an Al/Fe molar ratio of from 3.0 to 6.0%. The magnetic powder preferably has an activation volume Vact of from 1,400 to 1,800 nm3. The magnetic powder particularly preferably has a coercive force Hc of from 159 to 279 kA/m (which is approximately from 2,000 to 3,500 Oe) and a coercivity distribution SFD of from 0.3 to 1.0. The magnetic powder may contain, as an element that substitutes an Fe site of the hexagonal ferrite, at least one kind selected from divalent transition metals M1 and tetravalent transition metals M2.

Abstract: A hexagonal ferrite magnetic powder for a magnetic recording medium, containing magnetic powder contains hexagonal ferrite particles having coated on the surface thereof an aluminum hydroxide material, having a Ba/Fe molar ratio of 0.080 or more, a Bi/Fe molar ratio of 0.025 or more, and an Al/Fe molar ratio of from 0.030 to 0.200. The magnetic powder preferably has an activation volume Vact of from 1,300 to 2,000 nm3. The magnetic powder particularly preferably has a coercive force Hc of from 159 to 287 kA/m (approximately from 2,000 to 3,600 Oe) and a coercivity distribution SFD of from 0.3 to 1.0. The magnetic powder may contain one or two or more kinds of a divalent transition metal M1 and a tetravalent transition metal M2, as an element that replaces Fe of the hexagonal ferrite. The magnetic powder has improved magnetic characteristics including SNR and durability.

Abstract: Provided is magnetic powder capable of enhancing simultaneously both magnetic characteristics including SNP and durability of a magnetic recording medium. The hexagonal ferrite magnetic powder for a magnetic recording medium has a Ba/Fe molar ratio of 8.0% or more, a Bi/Fe molar ratio of 2.5% or more and an Al/Fe molar ratio of from 3.0 to 6.0%. The magnetic powder preferably has an activation volume Vact of from 1,400 to 1,800 nm3. The magnetic powder particularly preferably has a coercive force Hc of from 159 to 279 kA/m (which is approximately from 2,000 to 3,500 Oe) and a coercivity distribution SFD of from 0.3 to 1.0. The magnetic powder may contain, as an element that substitutes an Fe site of the hexagonal ferrite, at least one kind selected from divalent transition metals M1 and tetravalent transition metals M2.

Abstract: A magnetic powder for magnetic recording medium comprises acicular particles constituted primarily of Fe, wherein the powder contains Co in an amount such that the Co/Fe ratio is 50 at. % or less and the Co is contained in a manner such that the surface portion has a higher concentration than the core portion of the particles, and upon subjecting the magnetic powder for magnetic recording medium to TG measurement, the powder exhibits at least two oxidation starting points: a low-temperature side oxidation starting point and a high-temperature side oxidation starting point. The magnetic powder achieves improved resistance to oxidation without sacrificing magnetic characteristics.

Abstract: A hexagonal crystal ferrite magnetic powder having high magnetic characteristics while having a small particle volume and a high specific surface area is provided, and a high-density magnetic recording medium using the powder. A method for producing a hexagonal crystal ferrite formed using a glass crystallization method includes the steps of: mixing a glass matrix with raw materials including iron, bismuth, a divalent metal (M1), a tetravalent metal (M2), any one kind (A) of barium, strontium, calcium, and lead, and at least one kind of rare earth element (represented by R) having a mole equal to or less than that of the iron; heating the mixed raw material to obtain a glass body; quenching the glass body, pulverizing the glass body, and performing a heat treatment, and washing the glass body after the heat treatment with an acid solution.

Abstract: A hexagonal ferrite magnetic powder with a reduced amount of contaminants such as organic materials and a magnetic recording medium using the same are provided. The magnetic recording medium is formed using such a hexagonal ferrite magnetic powder that, when 0.10 mol/L nitric acid is added in an amount that changes the pH of 100 mL of a pH 11 potassium hydroxide solution (a blank solution) to 5 to a solution prepared by adding 0.05 g of the powder to 100 mL of the pH 11 potassium hydroxide solution, the pH of the resultant solution is 5 or higher.

Abstract: A hexagonal crystal ferrite magnetic powder having high magnetic characteristics while having a small particle volume and a high specific surface area is provided, and a high-density magnetic recording medium using the powder. A method for producing a hexagonal crystal ferrite formed using a glass crystallization method includes the steps of: mixing a glass matrix with raw materials including iron, bismuth, a divalent metal (M1), a tetravalent metal (M2), any one kind (A) of barium, strontium, calcium, and lead, and at least one kind of rare earth element (represented by R) having a mole equal to or less than that of the iron; heating the mixed raw material to obtain a glass body; quenching the glass body, pulverizing the glass body, and performing a heat treatment, and washing the glass body after the heat treatment with an acid solution.

Abstract: A method for producing a magnetic powder comprised chiefly of Fe16N2 comprising providing a starting powder comprising an oxy-hydroxide or oxide of iron and an amount of noble metal. The starting powder is reduced into an iron powder by a dry method using a hydrogen gas; and the iron powder is nitrided into a magnetic powder comprised chiefly of Fe16N2 particles using a nitrogen-containing gas at a temperature not higher than 200° C. The amount of noble metal is such that an amount that the atomic percent ratio of the noble metal content to Fe in the magnetic powder is 0.01-10.

Abstract: A magnetic powder for magnetic recording medium comprises acicular particles constituted primarily of Fe, wherein the powder contains Co in an amount such that the Co/Fe ratio is 50 at. % or less and the Co is contained in a manner such that the surface portion has a higher concentration than the core portion of the particles, and upon subjecting the magnetic powder for magnetic recording medium to TG measurement, the powder exhibits at least two oxidation starting points: a low-temperature side oxidation starting point and a high-temperature side oxidation starting point. The magnetic powder achieves improved resistance to oxidation without sacrificing magnetic characteristics.

Abstract: An iron system magnetic powder, and particularly an iron system magnetic powder comprised chiefly of Fe16N2, is provided that has an atomic ratio of total noble metal content to Fe of 0.01-10%. The magnetic powder can be produced by subjecting iron oxy-hydroxide or iron oxide having an atomic ratio of total noble metal content to Fe of 0.01-10% to reduction treatment. The average particle volume of the magnetic powder is preferably 4,000 nm3 or less. The magnetic powder is suitable for fabricating high recording density media of low noise, high output and high C/N ratio that are suitable for use with a GMR head or the like.

Abstract: Provided is an iron nitride-based magnetic powder that comprises magnetic particles having a mean particle size of at most 20 nm. The magnetic particle has a core of a main phase of Fe16N2 and has, on the outer side of the core, an oxide phase derived from a metal Fe phase formed by reduction of iron nitride. In relation to the weatherability index ??s and the saturation magnetization as thereof, the magnetic powder satisfies ??s?0.8×?s?30. In this, ??s=(?s??s1)/?s×100. ?s1 means the saturation magnetization of the magnetic powder kept in an atmosphere of 60° C. and 90% RH for 1 week. The powder can be obtained by exposing powder particles having a main phase of Fe16N2 to a reducing gas to partly reduce the region of the surface of the particles into a metal Fe phase (gradual reduction) followed by exposing them to an oxidizing gas to oxidize a part of the surface of the metal Fe phase into an oxide phase (gradual oxidation).

Abstract: A high-reliability iron nitride-based magnetic powder with markedly improved weatherability with respect to deterioration over time of the magnetic properties in fine particles smaller than 25 nm is formed by adhering one or more of the elements Si and P to the surface of an iron nitride-based magnetic powder constituted primarily of Fe16N2 with an average grain size of 25 nm or less, where the total content of Si and P in the magnetic powder may be 0.1% or greater as an atomic ratio with respect to Fe. In particular, the invention provides an iron nitride-based magnetic powder such that the value ?Hc as defined by Equation (1) below is 5% or less and the value ??s as defined by Equation (2) below is 20% or less. ?Hc=(Hc0?Hc1)/Hc0100??(1) ??s=(?s0??s1)/?s0100??(2) Here, Hc1 and ?s1 are the coercivity and saturation magnetization, respectively, of the magnetic powder after being kept for one week at a constant temperature and constant humidity of 60° C. and 90% RH.

Abstract: An iron nitride magnetic powder consisting primarily of Fe16N2 phase whose average particle diameter determined by particle size measurement using a TEM micrograph is 20 nm or less and whose geometric standard deviation of the particle diameter is 1.4 or less. The iron nitride magnetic powder can be obtained by a method of producing an iron nitride magnetic powder consisting primarily of Fe16N2 phase includes a step of, at the time of producing an iron nitride magnetic powder consisting primarily of Fe16N2 phase by subjecting a reduced powder obtained by reduction of iron oxide to ammonia treatment, using goethite containing Al in solid solution as the iron oxide.