Granted Patent B2

US 9,672,950 · App. 13/934,678 · Granted Jun 6, 2017

Abstract

Claims (16)

1. A method comprising: growing metal nanowires from a reaction solution including a metal salt and a reducing agent, wherein the growing includes:

reacting a first portion of the metal salt and the reducing agent in the reaction solution for a first period of time, wherein the first portion of the metal salt is reduced and grows in both a radial direction and an axial direction to form a plurality of precursors of metal nanowires; and

gradually adding a second portion of the metal salt over a second period of time while maintaining a substantially constant concentration of less than 0.1% w/w of the metal salt in the reaction solution, wherein the plurality of precursors of metal nanowires predominantly grow in the axial direction to form the metal nanowires.

2. The method of claim 1 wherein the metal nanowires are silver nanowires, the metal salt is silver nitrate, and the reducing agent is propylene glycol.

3. The method of claim 1 wherein reacting a first portion of the metal salt and the reducing agent in the reaction solution for the first period of time includes:

adding a fraction of the first portion of the metal salt with an ammonium salt; and

adding a remainder of the first portion of the metal salt.

4. The method of claim 3 wherein the ammonium salt is tetra-n-butylammonium chloride (TBAC).

5. The method of claim 3 wherein the fraction of the first portion of the metal salt represents about 0.6% of metal salt.

6. The method of claim 3 wherein the fraction of the first portion of the metal salt represents about 0.001% to 0.025% w/w of metal ions in the reaction solution.

7. The method of claim 1 wherein the first portion and the second portion of the metal salt are about equal amounts.

8. The method of claim 1 wherein the reaction solution further includes polyvinylpyrrolidone.

9. The method of claim 1 further including, after adding the second portion of the metal salt over the second period of time,

allowing the reaction solution to run; and

arresting growth of the metal nanowires by quenching the reaction solution with water.

10. The method of claim 1 , wherein the metal nanowires have a mean diameter of about 29 nm.

Assignments (9)