Preparing method of green man-made diamond

Abstract

The invention relates to a preparation method of a green man-made 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 Mg3N2 additive is added into the plumbago, the mass ratio of the plumbago and the Mg3N2 is that plumbago: Mg3N2 is equal to 1:0.003-0.02; the preparation technique process is that: the powdery plumbago, Mg3N2 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; then the assembled synthesized block is placed into a high pressure and high temperature chamber of a hexahedral anvil diamond press, then the temperature raises to 1550-2000K within 0.5-5 minutes and at the same time the block is pressurized at the pressure of 4.0-4.8 GPa, then is kept at the temperature for 0.5-3 minutes, and then the pressure is improved to 5.2-6.0 GPa, then is kept at the temperature for 10-20 minutes, then a green diamond crystal can be obtained after the heating process is stopped, the pressure is relieved and the impurities are removed. The 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 artificial 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...

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