Abstract: [Solving Means] A method of producing a magnetic powder includes: coating a surface of each of silica-coated precursor particles with at least one type of coating agent of a metal chloride or a sulfate; and firing the precursor particles coated with the coating agent.

Abstract: Provided is a magnetic recording medium that is able to achieve both an improvement in electromagnetic conversion characteristics and ensuring of high long-term reliability. The magnetic recording medium includes a magnetic layer and a base. The magnetic layer includes magnetic powders including ?-iron oxide. A ratio (Hrp/Hc) of residual coercivity (Hrp) measured in a perpendicular direction of the magnetic recording medium with use of a pulse magnetic field to perpendicular coercivity (Hc) of the magnetic recording medium is 2.0 or less. Saturation magnetization (Mst) per unit area of the magnetic recording medium is 4.5 mA or greater.

Abstract: A cobalt ferrite magnetic powder includes magnetic particles that have a uniaxial crystal magnetic anisotropy and contain cobalt ferrite. A peak top 2? of a (3, 1, 1) plane determined by powder X-ray diffractometry using a CoK? ray is 41.3° or more and 41.5° or less. Some Cos contained in the magnetic particles are substituted with at least one selected from the group consisting of Zn, Ge, and a transition metal element other than Fe.

Abstract: A magnetic recording medium is a tape-shaped magnetic recording medium that has a recording layer including an ?-iron oxide particle. An area ratio Rlow (=(Slow/Stotal)×100) of a total area Stotal of an SFD curve of the recording layer in a perpendicular direction and an area Slow of the SFD curve in which a coercivity Hc is in a range from ?500 [Oe]?Hc?500 [Oe] is equal to or less than 5.5%.

Abstract: A method of producing a magnetic powder includes: performing heat treatment on first particles that contain triiron tetraoxide to prepare second particles that contain ?-iron oxide.

Abstract: The magnetic recording medium includes a long substrate body, and a magnetic layer including a powder of cubic crystal ferrite magnetic particles. The sum of a squareness ratio in the longitudinal direction and a squareness ratio in the vertical direction is 1.2 or more, and the difference of the squareness ratio in the longitudinal direction and the squareness ratio in the vertical direction is 0.15 or more.

Abstract: [Solving Means] A tape-shaped magnetic recording medium includes: a base; and a magnetic layer that is provided on the base and includes a magnetic powder. The magnetic powder includes magnetic particles that have a uniaxial crystal magnetic anisotropy and contain cobalt ferrite. A ratio L4/L2 of a component L4 having a multiaxial crystal magnetic anisotropy to a component L2 having a uniaxial crystal magnetic anisotropy is 0 or more and 0.25 or less, the components being obtained by applying Fourier transformation to a torque waveform of the magnetic recording medium.

Abstract: A tape-shaped magnetic recording medium includes a base, a nonmagnetic layer that is provided on the base and contains a nonmagnetic powder, and a magnetic layer that is provided on the nonmagnetic layer and contains a magnetic powder. In the magnetic recording medium, the magnetic layer has an average thickness of not more than 90 nm, the magnetic powder has an average aspect ratio of from 1.0 to 3.0, a coercive force Hc1 in a perpendicular direction is not more than 3,000 Oe, the coercive force Hc1 in the perpendicular direction and a coercive force Hc2 in a longitudinal direction satisfy the relation of Hc2/Hc1?0.8, the nonmagnetic layer has an average thickness of not more than 1.1 ?m, and the nonmagnetic powder has an average particle volume of not more than 2.0×10?5 ?m3.

Abstract: [Object] A cobalt ferrite magnetic powder includes magnetic particles that have a uniaxial crystal magnetic anisotropy and contain cobalt ferrite. A peak top 2? of a (3, 1, 1) plane determined by powder X-ray diffractometry using a CoK? ray is 41.3° or more and 41.5° or less. Some Cos contained in the magnetic particles are substituted with at least one selected from the group consisting of Zn, Ge, and a transition metal element other than Fe.

Abstract: A tape-shaped magnetic recording medium includes a substrate; and a magnetic layer that is provided on the substrate and contains a magnetic powder. An average thickness of the magnetic layer is not more than 90 nm, an average aspect ratio of the magnetic powder is not less than 1.0 and not more than 3.0, the coercive force Hc1 in a vertical direction is not more than 3000 Oe, and the coercive force Hc1 in the vertical direction and a coercive force Hc2 in a longitudinal direction satisfy a relationship of Hc2/Hc1?0.8.

Abstract: A method of producing a magnetic powder includes performing heat treatment on first particles that contain ferrous oxide to prepare 5 second particles that contain ?-iron oxide.

Abstract: A tape-shaped magnetic recording medium includes a substrate; and a magnetic layer that is provided on the substrate and contains a magnetic powder. An average thickness of the magnetic layer is not more than 90 nm, an average aspect ratio of the magnetic powder is not less than 1.0 and not more than 3.0, the coercive force Hc1 in a vertical direction is not more than 3000 Oe, the coercive force Hc1 in the vertical direction and a coercive force Hc2 in a longitudinal direction satisfy a relationship of Hc2/Hc1?0.8, and a value of ?1.5??0.5 is not more than 0.6 N in a tensile test of the magnetic recording medium in the longitudinal direction, where ?0.5 is a load at an elongation rate of 0.5% in the magnetic recording medium and ?1.5 is a load at an elongation rate of 1.5% in the magnetic recording medium.

Abstract: A method of producing a magnetic powder includes: performing heat treatment on first particles that contain triiron tetraoxide to prepare second particles that contain ?-iron oxide.

Abstract: [Solving Means] A method of producing a magnetic powder includes: coating a surface of each of silica-coated precursor particles with at least one type of coating agent of a metal chloride or a sulfate; and firing the precursor particles coated with the coating agent.

Abstract: A tape-shaped magnetic recording medium includes a base, a nonmagnetic layer that is provided on the base and contains a nonmagnetic powder, and a magnetic layer that is provided on the nonmagnetic layer and contains a magnetic powder. In the magnetic recording medium, the magnetic layer has an average thickness of not more than 90 nm, the magnetic powder has an average aspect ratio of from 1.0 to 3.0, a coercive force Hc1 in a perpendicular direction is not more than 3,000 Oe, the coercive force Hc1 in the perpendicular direction and a coercive force Hc2 in a longitudinal direction satisfy the relation of Hc2/Hc1?0.8, the nonmagnetic layer has an average thickness of not more than 1.1 ?m, and the nonmagnetic powder has an average particle volume of not more than 2.0×10?5 ?m3.

Abstract: A tape-shaped magnetic recording medium includes a substrate; and a magnetic layer that is provided on the substrate and contains a magnetic powder. An average thickness of the magnetic layer is not more than 90 nm, an average aspect ratio of the magnetic powder is not less than 1.0 and not more than 3.0, the coercive force Hc1 in a vertical direction is not more than 3000 Oe, and the coercive force Hc1 in the vertical direction and a coercive force Hc2 in a longitudinal direction satisfy a relationship of Hc2/Hc1?0.8.

Abstract: A magnetic recording medium according to a first technique includes an elongated substrate having a first surface and a second surface, a first reinforcing layer disposed on the first surface, a second reinforcing layer disposed on the second surface, an adhesion suppressing layer disposed on the second reinforcing layer, and a recording layer disposed on the first reinforcing layer or the adhesion suppressing layer.

Abstract: A tape-shaped magnetic recording medium includes a substrate; and a magnetic layer that is provided on the substrate and contains a magnetic powder. An average thickness of the magnetic layer is not more than 90 nm, an average aspect ratio of the magnetic powder is not less than 1.0 and not more than 3.0, the coercive force Hc1 in a vertical direction is not more than 3000 Oe, the coercive force Hc1 in the vertical direction and a coercive force Hc2 in a longitudinal direction satisfy a relationship of Hc2/Hc1?0.8, and a value of ?1.5??0.5 is not more than 0.6 N in a tensile test of the magnetic recording medium in the longitudinal direction, where ?0.5 is a load at an elongation rate of 0.5% in the magnetic recording medium and ?1.5 is a load at an elongation rate of 1.5% in the magnetic recording medium.

Abstract: The magnetic recording medium includes a support and a magnetic layer containing a magnetic powder. The magnetic powder includes at least either of a magnetic particle containing a cubic ferrite and a magnetic particle containing an ?-phase iron oxide. The magnetic powder has a mean particle size of 10 nm or more and 14 nm or less, the magnetic powder has a mean aspect ratio of 0.75 or more and 1.25 or less, and the magnetic layer has a ten-point mean roughness Rz of 35 nm or less.

Abstract: A magnetic recording medium includes an elongated substrate, and a reinforcing layer and a carbon thin film disposed on one surface of the substrate.