Epsilon iron oxide and method for producing the same, magnetic coating material and magnetic recording medium
US-10807880-B2 · Oct 20, 2020 · US
ϵ-iron oxide type ferromagnetic powder and magnetic recording medium
US11090716B2 · US · B2
| Field | Value |
|---|---|
| Publication number | US-11090716-B2 |
| Application number | US-201715825469-A |
| Country | US |
| Kind code | B2 |
| Filing date | Nov 29, 2017 |
| Priority date | Nov 30, 2016 |
| Publication date | Aug 17, 2021 |
| Grant date | Aug 17, 2021 |
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Abstract
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Provided is an ε-iron oxide type ferromagnetic powder with a ratio Hc173K/Hc296K between a coercive force Hc173K measured at a temperature of 173 K and a coercive force Hc296K measured at a temperature of 296 K is higher than 1.00 and less than 2.00, and a magnetic recording medium containing the ε-iron oxide type ferromagnetic powder in a magnetic layer.
First claim
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What is claimed is: 1. An √-iron oxide type ferromagnetic powder for use in a magnetic layer of a magnetic recording medium, comprising one or more elements from the group consisting of Co, Mn, and Ni, wherein a ratio Hc 173K /Hc 296K between a coercive force Hc 173K measured at a temperature of 173 K and a coercive force Hc 296K measured at a temperature of 296 K is higher than 1.00 and less than 2.00. 2. The √-iron oxide type ferromagnetic powder according to claim 1 , wherein a content rate of the elements selected from the group consisting of Co, Mn, and Ni is equal to or higher than 1 at % and equal to or lower than 50 at % with respect to a total of 100 at % of Fe and the elements selected from the group consisting of Co, Mn, and Ni. 3. The √-iron oxide type ferromagnetic powder according to claim 1 , comprising: an element capable of substituting Fe in an √-iron oxide type crystal structure, wherein the element capable of substituting Fe in the √-iron oxide type crystal structure consists of an element selected from the group consisting of Co, Mn, and Ni. 4. The √-iron oxide type ferromagnetic powder according to claim 1 , wherein the √-iron oxide type ferromagnetic powder contains at least Co. 5. The √-iron oxide type ferromagnetic powder according to claim 1 , wherein the ratio is equal to or higher than 1.10 and equal to or lower than 1.90. 6. The √-iron oxide type ferromagnetic powder according to claim 1 , wherein the ratio is equal to or higher than 1.20 and equal to or lower than 1.85. 7. The √-iron oxide type ferromagnetic powder according to claim 1 , wherein the ratio Hc 173K /Hc 296K , is equal to or higher than 1.15 and equal to or lower than 1.85. 8. The √-iron oxide type ferromagnetic powder according to claim 1 , wherein the ratio Hc 173K /Hc 296K is equal to or higher than 1.18 and less than 2.00. 9. A magnetic recording medium comprising: a non-magnetic support; and a magnetic layer which is on the support and contains a ferromagnetic powder and a binder, wherein the ferromagnetic powder is an √-iron oxide type ferromagnetic powder comprising one or more elements selected from the group consisting of Co, Mn, and Ni, wherein a ratio Hc 173K /Hc 296K between a coercive force Hc 173K measured at a temperature of 173 K and a coercive force Hc 296K measured at a temperature of 296 K is higher than 1.00 and less than 2.00. 10. The magnetic recording medium according to claim 9 , wherein a content rate of the elements selected from the group consisting of Co, Mn, and Ni in the √-iron oxide type ferromagnetic powder is equal to or higher than 1 at % and equal to or lower than 50 at % with respect to a total of 100 at % of Fe and the elements selected from the group consisting of Co, Mn, and Ni. 11. The magnetic recording medium according to claim 9 , wherein the √-iron oxide type ferromagnetic powder comprises an element capable of substituting Fe in an √-iron oxide type crystal structure, and the element capable of substituting Fe in the √-iron oxide type crystal structure consists of an element selected from the group consisting of Co, Mn, and Ni. 12. The magnetic recording medium according to claim 9 , wherein the √-iron oxide type ferromagnetic powder contains at least Co. 13. The magnetic recording medium according to claim 9 , wherein the ratio of the √-iron oxide type ferromagnetic powder is equal to or higher than 1.10 and equal to or lower than 1.90. 14. The magnetic recording medium according to claim 9 , wherein the ratio of the √-iron oxide type ferromagnetic powder is equal to or higher than 1.20 and equal to or lower than 1.85. 15. The magnetic recording medium according to claim 9 , wherein the ratio Hc 173K /Hc 296K , is equal to or higher than 1.15 and equal to or lower than 1.85. 16. The magnetic recording medium according to claim 9 , wherein the ratio Hc 173K /Hc 296K is equal to or higher than 1.18 and less than 2.00.
Assignees
Inventors
Classifications
Metallic powder containing lubricating or binding agents; Metallic powder containing organic material · CPC title
- G11B5/70642Primary
iron oxides · CPC title
obtained by a reduction · CPC title
Aspects linked to processes or compositions used in powder metallurgy · CPC title
Submicrometer sized, i.e. from 0.1-1 micrometer · CPC title
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Frequently asked questions
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- What does patent US11090716B2 cover?
- Provided is an ε-iron oxide type ferromagnetic powder with a ratio Hc173K/Hc296K between a coercive force Hc173K measured at a temperature of 173 K and a coercive force Hc296K measured at a temperature of 296 K is higher than 1.00 and less than 2.00, and a magnetic recording medium containing the ε-iron oxide type ferromagnetic powder in a magnetic layer.
- Who is the assignee on this patent?
- Fujifilm Corp
- What technology area does this patent fall under?
- Primary CPC classification G11B5/70642. Mapped technology areas include Physics.
- When was this patent published?
- Publication date Tue Aug 17 2021 00:00:00 GMT+0000 (Coordinated Universal Time) (B2). Legal status and post-grant events are not shown on this page.
- What related patents are in patentsdb?
- We list 3 related publications on this page (citations in our corpus or others sharing the same primary CPC).