Iron cobalt ternary alloy nanoparticles with silica shells and metal silicate interface

Patent metadata

Field	Value
Publication number	US-9431159-B2
Application number	US-201414521063-A
Country	US
Kind code	B2
Filing date	Oct 22, 2014
Priority date	Mar 5, 2014
Publication date	Aug 30, 2016
Grant date	Aug 30, 2016

Abstract

Superparamagnetic core-shell nanoparticles having a core of an iron cobalt ternary alloy, a shell of a silicon oxide on the core and a metal silicate interface layer between the core and the shell layer are provided. Methods to prepare the nanoparticles are also provided.

First claim

The invention claimed is:

1. A core-shell nanoparticle, comprising:
a core of an iron cobalt ternary alloy;
a shell of a silicon oxide coating the core; and
a metal silicate interface in a region between the core and the shell;
wherein
the third component of the ternary alloy is a transition metal selected from the group consisting of scandium, titanium, vanadium, chromium, manganese, nickel, copper and zinc,
a particle size of the nanoparticle is from 2 to 200 nm, and
the metal silicate of the metal silicate interface comprises at least one of iron silicate, cobalt silicate and the third component transition metal silicate.

2. The core shell nanoparticles according to claim 1 , wherein the metal silicate interface is magnetically active.

3. The core shell nanoparticles according to claim 1 , wherein the metal silicate interface comprises iron silicate and cobalt silicate.

4. The core shell nanoparticles according to claim 1 , wherein a width of the region of the interface is from 0.1 to 10 nm.

5. The core shell nanoparticles according to claim 1 , wherein the iron cobalt ternary alloy is an iron cobalt vanadium alloy.

6. The core shell nanoparticles according to claim 1 , wherein the iron cobalt ternary alloy is an iron cobalt chromium alloy.

7. The core shell nanoparticles according to claim 5 , wherein the metal silicate interface comprises iron silicate, cobalt silicate and chromium silicate.

8. The core shell nanoparticles according to claim 5 , wherein the metal silicate interface comprises iron silicate, cobalt silicate and vanadium silicate.

9. The core shell nanoparticles according to claim 1 , wherein the silicon oxide of the shell is silicon dioxide.

10. The core-shell nanoparticles according to claim 1 , wherein the particle size of the nanoparticle is from 2 to 160 nm.

11. A method to prepare the core-shell nanoparticles according to claim 1 , the method comprising:
dissolving each of an iron salt, a cobalt salt and a transition metal salt in an alkaline alcoholic solution in the presence of a ligand;
treating the solution with a reducing agent to produce nanoparticles of an iron cobalt ternary alloy under an inert atmosphere;
coating the alloy particles with a silicon oxide shell to obtain the core shell nanoparticles;
isolating and drying the obtained core-shell nanoparticles.

12. The method of claim 11 , wherein the reducing agent is a metal hydride.

13. The method of claim 12 , wherein the metal hydride is sodium borohydride.

14. The method of claim 11 , wherein coating the alloy particle comprises:
dispersing the alloy nanoparticles in an aqueous solution of a trialkylamine;
adding a tetraalkyl orthosilicate to the dispersion; and
reacting the orthosilicate to form a silicon oxide coating on the nanoparticles.

15. The method of claim 11 , wherein the transition metal other than iron and cobalt is selected from the group consisting of scandium, titanium, vanadium, chromium, manganese, nickel, copper and zinc.

16. The method according to claim 15 , wherein the transition metal is vanadium or chromium.

17. The method according to claim 11 , wherein the alkaline alcoholic solution comprises at least one selected from the group consisting of methanol, ethanol, n-propanol, 2-propanol, n-butanol and 2-butanol.

18. The method according to claim 11 , wherein the ligand is a tetraalkylammonium halide.

19. The method according to claim 11 , wherein the ligand is tetraoctylammonium bromide.

Assignees

• Toyota Motor Eng & Mfg North America Inc

Inventors

• Rowe Michael Paul
• Desautels Ryan Daniel

Classifications

• H01F1/0054 Primary

  Coated nanoparticles, e.g. nanoparticles coated with organic surfactant · CPC title

• H01F41/005

  Impregnating or encapsulating (insulating of windings H01F41/12) · CPC title

• H01F1/33 Primary

  mixtures of metallic and non-metallic particles; metallic particles having oxide skin · CPC title