Preparing method of green diamond

Abstract

The invention relates to a preparation method of a green diamond, which adopts plumbago as the material and FeNi or NiMnCo alloy as the catalyst, the mass ratio of the plumbago and alloy catalyst is that plumbago:FeNi or NiMnCo is equal to 1:0.3-1. The invention is characterized in that Li3N additive is added into the plumbago, and the mass ratio of the plumbago and the Li3N is that plumbago:Li3N is equal to 1:0.005-0.025; the preparation process is that: the powdery plumbago, Li3N and alloy catalyst meeting the mass ratio are mixed evenly, pre-pressed into cylindrical bar stock and then are placed into a pyrophyllite synthesized block; the assembled synthesized block is placed into a high pressure and high temperature chamber of a hexahedral anvil diamond press, then the temperature is raised to 1450-1950K within 0.5-5 minutes and at the same time the block is pressurized at the pressure of 4.0-4.8 GPa, and is kept at this temperature for 0.5-3 minutes; then the pressure is improved to 5.2-5.8 GPa, and is kept at the temperature for 8-20 minutes; then a green diamond crystal can be obtained after the heating process is stopped, the pressure is relieved and the impurities are removed. This method simplifies the technique process, reduces the manufacturing cost and is convenient for being carried out.

Description

technical field [0001] The invention relates to a method for preparing artificial diamond, in particular to a method for preparing green diamond. Background technique [0002] Diamond contains a certain amount of impurity elements, and these impurity elements directly affect the properties of diamond. Some impurity elements can improve certain properties of diamond, for example: phosphorus or boron can improve the optical properties, mechanical properties, electrical properties and thermal properties of diamond, etc., thus affecting the potential of diamond in industrial development and science and technology use. [0003] Nitrogen is the most important impurity element in diamond. The mechanical, optical, thermal and electrical properties of diamond will be changed due to the presence of nitrogen impurities. According to the existence form of boron, nitrogen impurities in diamond and the impurities themselves in the crystal lattice, diamonds are usually divided into four ...

AI Technical Summary

Problems solved by technology

However, ordinary synthetic diamonds are mostly synthesized by metal catalysts and graphite systems. The concentration of nitrogen in diamonds is only about 300ppm, and the color of diamonds appears light yellow or yellow.

So far, foreign literature has reported that the concentration of nitrogen in artificially synthesized diamonds using traditional metal catalysts under high temperature and high pressure conditions can only reach 800ppm, and such diamonds appear dark yellow; while foreign countries mainly use non-metallic catalysts (Na 2 SO 4 、Na 2 CO 3 , hydroxide, etc.) under the harsh conditions of 7.7GPa and 2300K to synthesize nitrogen-rich diamonds, the synthetic diamonds have a small particle size (about 50 μm) and no complete crystal shape. Due to the small particle size and the presence of aggregated nitrogen, etc., diamond appears colorless