Abstract: An R-T-B based alloy strip including columnar crystals of an R2T14B phase, wherein in a cross-section along the thickness direction, columnar crystals extend out in a radial fashion from the crystal nuclei, the R-T-B based alloy strip satisfying the following inequality (1), where D1 and D2 are, respectively, the average value for the lengths of the columnar crystals on one side and the average value for the lengths on the other side that is opposite the one side, in the direction perpendicular to the thickness direction of the cross-section. 0.9/1.1?D2/D1?1.1/0.

Abstract: An R-T-B sintered magnet including a composition containing a rare earth element, a transition element and boron, containing essentially no dysprosium as a rare earth element, and having crystal grains with a composition containing a rare earth element, a transition element and boron, and grain boundary regions formed between the crystal grains, wherein the triple point regions which are grain boundary regions surrounded by 3 or more crystal grains have a composition containing a rare earth element, a transition element and boron and have a higher mass ratio of the rare earth element than the crystal grains, the average value of the area of the triple point regions in a cross-section being no greater than 2 ?m2 and the standard deviation of the area distribution being no greater than 3.

Abstract: An R-T-B based alloy strip containing dendritic crystals including a R2T14B phase, wherein on at least one surface, the average value for the widths of the dendritic crystals is no greater than 60 ?m, and the number of crystal nuclei in the dendritic crystals is at least 500 per 1 mm square area.

Abstract: An R-T-B based alloy strip including columnar crystals of an R2T14B phase, wherein in a cross-section along the thickness direction, columnar crystals extend out in a radial fashion from the crystal nuclei, the R-T-B based alloy strip satisfying the following inequality (1), where D1 and D2 are, respectively, the average value for the lengths of the columnar crystals on one side and the average value for the lengths on the other side that is opposite the one side, in the direction perpendicular to the thickness direction of the cross-section. 0.9/1.1?D2/D1?1.1/0.

Abstract: An R-T-B based alloy strip containing dendritic crystals including a R2T14B phase, wherein on at least one surface, the average value for the widths of the dendritic crystals is no greater than 60 ?m, and the number of crystal nuclei in the dendritic crystals is at least 500 per 1 mm square area.

Abstract: An R-T-B sintered magnet including a composition containing a rare earth element, a transition element and boron, containing essentially no dysprosium as a rare earth element, and having crystal grains with a composition containing a rare earth element, a transition element and boron, and grain boundary regions formed between the crystal grains, wherein the triple point regions which are grain boundary regions surrounded by 3 or more crystal grains have a composition containing a rare earth element, a transition element and boron and have a higher mass ratio of the rare earth element than the crystal grains, the average value of the area of the triple point regions in a cross-section being no greater than 2 ?m2 and the standard deviation of the area distribution being no greater than 3.

Abstract: An R-T-B sintered magnet 100 including particles containing an R2T14B phase, obtained using an R-T-B alloy strip containing crystal grains of an R2T14B phase, wherein the R-T-B alloy strip has, in a cross-section along the thickness direction, the crystal grains extending in a radial fashion from the crystal nuclei, the following inequality (1) being satisfied, where the average value of the lengths of the crystal grains on one side in the direction perpendicular to the thickness direction and the average value of the lengths on the other side opposite the one side are represented as D1 and D2, respectively, the mean particle diameter of the particles is 0.5 to 5 ?m, and essentially no heavy rare earth elements are present. 0.9?D2/D1?1.

Abstract: The invention provides a process for production of an oxide fine particle powder including a heating step in which a dry powder of a metal complex gel is heat treated to obtain an oxide fine particle powder, wherein the heating step is carried out in two stages with different oxygen concentrations, or at least part of the heating step is carried out in a water vapor-containing atmosphere.

Abstract: The present invention provides a magnetic recording medium capable of obtaining high recording density and also having a hardly charged magnetic layer. The magnetic recording tape 2 (magnetic recording medium) of a preferable embodiment has a magnetic layer 6 containing a SmCo magnetic fine particle 12 and a hydrophilic binder, wherein the SmCo magnetic fine particle 12 has a core 14 made of a SmCo nano particle and a coating layer 16 made of a hydrophilic polymer and coating at least a part of a surface of the core 14.

Abstract: The invention provides a magnetic recording medium with both weather resistance and high recording density. The magnetic recording medium of the invention has a magnetic layer comprising at least SmCo-based magnetic fine particles and a hydrophobic binder, wherein the SmCo-based magnetic fine particles include a core composed of SmCo-based nanoparticles and a hydrophilic polymer covering at least a portion of the surface of the core.

Abstract: The invention provides weather-resistant SmCo-based magnetic fine particles and a magnetic recording medium with both weather resistance and high recording density. The SmCo-based magnetic fine particles of the invention include SmCo-based nanoparticles and a hydrophobic polymer covering at least part of the surfaces of the SmCo-based nanoparticles. The magnetic recording medium of the invention also has a magnetic layer comprising at least SmCo-based magnetic fine particles and a hydrophobic binder, wherein the SmCo-based magnetic fine particles include SmCo-based nanoparticles and a hydrophobic polymer covering at least part of the SmCo-based nanoparticle surfaces.

Abstract: The present invention provides a magnetic recording medium having a thinned film back coating layer as well as suppressed tribocharging by sliding to the tape guide pin on running, and having excellent running durability. The present invention also provides a magnetic recording/reproducing system using the magnetic recording medium above. A magnetic recording medium 1 which comprises at least a magnetic layer 3 and a protective layer 4 comprising a hard film containing carbon as a principal component in this order on one surface of a non-magnetic support 2, and comprises a metal layer 7 from 1 to 50 nm in thickness and a back coating layer 6 comprising a hard film containing carbon as a principal component in this order on the other surface of said non-magnetic support 2.

Abstract: The present invention provides a magnetic recording medium having a thinned film back coating layer as well as suppressed tribocharging by sliding to the tape guide pin on running, and having excellent running durability, and a method for producing the same. A magnetic recording medium which comprises at least a magnetic layer 3 and a protective layer 4 comprising a hard film containing carbon as a principal component in this order on one surface of a non-magnetic support 2, and comprises a back coating layer 6 comprising a hard film containing carbon as a principal component on the other surface of said non-magnetic support 2, wherein a surface of said back coating layer 6 has a three-dimension center surface roughness SRa in a range of 3 to 7 nm and a three-dimension ten-point average roughness SRz in a range of 30 to 55 nm.