Ferrite thick films and chemical solution-based methods of preparation thereof

Patent metadata

Field	Value
Publication number	US-10577253-B2
Application number	US-201715410067-A
Country	US
Kind code	B2
Filing date	Jan 19, 2017
Priority date	Jan 19, 2016
Publication date	Mar 3, 2020
Grant date	Mar 3, 2020

Abstract

Ferrite films, antennas including ferrite films, and methods of making thereof are provided. The methods can include tape casting of a slurry to produce a green film, wherein the slurry includes a ferrite powder, a dispersant, and a binder in a suitable solvent; and densifying the green film to produce the ferrite film having a thickness of 50 μm to 5 mm. The methods can be used to make large area films, for example the films can have a lateral area of about 1000 cm 2 to 3000 cm 2 . VHF/UHF antennas are including the ferrite films are also provided.

First claim

We claim:

1. A method of making a ferrite film, the method comprising
tape casting of a slurry to produce a green film, wherein the slurry comprises a ferrite powder, a dispersant, and a binder in a suitable solvent;
densifying the green film to produce the ferrite film having a thickness of 50 μm to 5 mm; and

wherein the ferrite powder is Ni 0.19 Zn 0.28 Co 0.03 Fe 2.5 O 4 .

2. The method of claim 1 , wherein the ferrite powder has an average particle diameter of about 20 nm to 50 nm.

3. The method of claim 1 , wherein the dispersant is a fish oil.

4. The method of claim 1 , wherein the binder is a polyvinyl butyral.

5. The method of claim 1 , wherein the solvent is ethanol.

6. The method of claim 1 , wherein the tape casting comprises casting the green film onto a glass or polymer substrate.

7. The method of claim 1 , wherein the tape casting comprises heating the green film to burnout the dispersant, the binder, and the solvent.

8. The method of claim 1 , wherein the densifying comprises heating the green film to a temperature of about 900° C. to 1400° C. and maintaining the temperature for a period of time of about 1 hour to 150 hours.

9. The method of claim 8 , wherein the heating is at a heating rate of about 2° C./min to 20° C./min.

10. The method of claim 1 , wherein the densifying comprises applying a pressure of about 40 MPa to 60 MPa to the green film.

11. The method of claim 1 , wherein the densifying comprises applying an electric field to the green film, and wherein the electrical field is pulsed with pulses that are about 500 μs to 300 ms.

12. A method of making a ferrite film, the method comprising
tape casting of a slurry to produce a green film, wherein the slurry comprises a ferrite powder, a dispersant, and a binder in a suitable solvent;
densifying the green film to produce the ferrite film having a thickness of 50 μm to 5 mm;
wherein the ferrite powder is Ni 0.19 Zn 0.28 CO 0.03 Fe 2.5 O 4 ; and
wherein the densifying comprises applying an electric field to the green film.

13. The method of claim 12 , wherein the electrical field is pulsed with pulses that are about 500 μs to 300 ms.

14. The method of claim 12 , wherein the ferrite powder has an average particle diameter of about 20 nm to 50 nm.

15. The method of claim 12 , wherein the binder is a polyvinyl butyral.

16. The method of claim 12 , wherein the solvent is ethanol.

17. The method of claim 12 , wherein the tape casting comprises casting the green film onto a glass or polymer substrate.

18. The method of claim 12 , wherein the tape casting comprises heating the green film to burnout the dispersant, the binder, and the solvent.

Assignees

• Univ North Carolina State

Inventors

• Schwartz Justin
• Kittel Taryn

Classifications

• H01Q17/004

  using non-directional dissipative particles, e.g. ferrite powders (H01Q17/005 takes precedence; flake-like H01Q17/002) · CPC title

• B29K2105/0073

  Solution · CPC title

• B29D7/01

  Films or sheets · CPC title

• B29C41/12

  Spreading-out the material on a substrate {, e.g. on the surface of a liquid} · CPC title

• C08J5/18

  Manufacture of films or sheets · CPC title