HEXAGONAL CRYSTAL FERRITE MAGNETIC POWDER

• Main Authors: TADA TOSHIO, OMOTO HIROHISA, SUZUKI HIROYUKI, KANEDA HIDEHARU
• Format: Patent
• Language: English; Japanese
• Published: 18.06.2020
• Subjects: BASIC ELECTRIC ELEMENTS; CHEMISTRY; COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSESC01D OR C01F; ELECTRICITY; INDUCTANCES; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; INORGANIC CHEMISTRY; MAGNETS; METALLURGY; PHYSICS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES; TRANSFORMERS

To provide magnetic powder capable of improving magnetic characteristics including SNR of a magnetic recording medium, and further improving durability at the same time.SOLUTION: Hexagonal crystal ferrite magnetic powder for a magnetic recording medium consists of magnetic particles that consist of aluminum hydroxide adhered on the surface of hexagonal ferrite particle, and Al/Fe molar ratio is 0.030-0.200, Co/Fe molar ratio is 0.002-0.030, Nb/Fe molar ratio is 0.005-0.050, Fe site valence Ais 3.015-3.040 by calculating A=(3+2×[Co/Fe]+5×[ Nb/Fe])/(1+[Co/Fe]+[Nb/Fe]), and preferably activation volume Vact is 1400-1800nm. In here, [Co/Fe] means the Co/Fe molar ratio, and [Nb/Fe] means the Nb/Fe molar ratio.SELECTED DRAWING: None 【課題】磁気記録媒体のＳＮＲを含めた磁気特性の向上と、耐久性の更なる向上とを同時に実現し得る磁性粉末を提供する。【解決手段】六方晶フェライト粒子の表面にアルミニウム水酸化物が被着した磁性粒子からなり、Ａｌ／Ｆｅモル比が０.０３０〜０.２００、Ｃｏ／Ｆｅモル比が０.００２〜０.０３０、Ｎｂ／Ｆｅモル比が０.００５〜０.０５０、ＡFe＝（３＋２×［Ｃｏ／Ｆｅ］＋５×［Ｎｂ／Ｆｅ］）／（１＋［Ｃｏ／Ｆｅ］＋［Ｎｂ／Ｆｅ］）により算出されるＦｅサイト価数ＡFeが３.０１５〜３.０４０であり、好ましくは活性化体積Ｖactが１４００〜１８００ｎｍ3である、磁気記録媒体用六方晶フェライト磁性粉。ここで、［Ｃｏ／Ｆｅ］はＣｏ／Ｆｅモル比、［Ｎｂ／Ｆｅ］はＮｂ／Ｆｅモル比を意味する。【選択図】なし