Method and apparatus for treating diamond using liquid metal saturated with carbon
A method of treating a diamond, the method comprising: (i) providing a liquid metal saturated with carbon with respect to graphite precipitation; (ii) lowering the temperature of the liquid metal such that the liquid metal is saturated with carbon with respect to diamond precipitation; (iii) immersing a diamond in the liquid metal; and (iv) removing the diamond from the metal.
1. A method of treating a diamond, comprising:
providing a liquid metal saturated with carbon with respect to graphite precipitation;
lowering the temperature of the liquid metal such that the liquid metal is saturated with carbon with respect to diamond precipitation;
immersing a diamond in the liquid metal and annealing the diamond;
exposing the liquid metal to atomic hydrogen plasma and/or atomic hydrogen radicals while the diamond is immersed in the liquid metal; and
removing the diamond from the liquid metal.
2. The method according to claim 1 , wherein the method is a method of reducing defects in a diamond and/or improving the optical properties of a diamond, and wherein the diamond is immersed in the liquid metal to reduce the defects in the diamond and/or improve the optical properties of the diamond.
3. The method according to claim 1 , wherein the method is a method of doping diamond, and wherein the diamond is immersed in the liquid metal in the presence of a dopant to dope the diamond with the dopant.
4. The method according to claim 3 , wherein the dopant is selected from boron, sulphur, phosphorus, aluminium and mixtures of two or more thereof.
5. The method according to claim 1 , wherein the metal comprises a single metallic element, an alloy, and/or two or more metallic elements.
6. The method according to claim 1 , wherein the metal is selected from lead, bismuth, tin, gold, silver, indium, gallium, antimony, nickel, cobalt, aluminum and mixtures of two or more thereof.
7. The method according to claim 6 , wherein the metal is lead.
8. The method according to claim 1 , wherein the method is carried out in a reaction chamber comprising an inert atmosphere.
9. The method according to claim 1 , wherein the liquid metal is at a temperature in the range of from 1000 to 2000° C. when the diamond is immersed in the liquid metal.
10. The method according to claim 9 , wherein the liquid metal is at a temperature in the range of from 1550 to 1750° C. when the diamond is immersed in the liquid metal.
11. The method according to claim 1 , wherein the liquid metal is cooled to a temperature of below 1500° C. before removing the diamond.
12. The method according to claim 1 , wherein the method is carried out at a pressure in the range of from 1 Pa to 133 kPa.
13. The method according to claim 1 , wherein the step of providing a liquid metal saturated with carbon with respect to graphite precipitation comprises the steps of:
(a) providing a vessel;
(b) placing a metal in a solid form in the vessel;
(c) placing carbon in the vessel;
(d) optionally providing an inert atmosphere in the vessel; and
(e) heating to provide liquid metal saturated with carbon with respect to graphite precipitation.
14. The method according to claim 1 , wherein the liquid metal is heated such that a temperature gradient exists across the liquid metal.
15. The method according to claim 14 ,wherein the temperature gradient across the liquid metal is at least 10° C. from the base of the liquid, preferably in a vessel, to the meniscus.
16. The method according to claim 1 , wherein the source of carbon in the metal is graphite.
17. The method according to claim 1 , wherein the diamond is synthetic diamond.
18. The method according to claim 1 , wherein the temperature is lowered by from 10 to 50° C. such that the liquid metal is saturated with carbon with respect to diamond precipitation.