A Patent Application For A Method To Improve The Purity Of Diamond

Recently, information from the State Intellectual Property Office showed that Harbin Institute of Technology, Harbin Institute of Technology Zhengzhou Research Institute, and Henan Carbon Core Materials Technology Co., Ltd. applied for a patent titled "A method for preparing CVD blue gradient diamond based on lead electron irradiation carrier", publication number CN119900077A, and application date December 2024.

 

The patent abstract shows a method for preparing CVD blue gradient diamond based on a lead electron irradiation carrier. The invention aims to solve the problem of existing colored diamonds by controlling the concentration of impurity gas doping during the growth of diamonds to adjust the color and avoid cracking in the subsequent processing of diamonds.

 

With the improvement of people's living standards, not only the demand for white diamonds has increased, but also the demand for high-quality colored diamonds has greatly increased. However, the more demanding growth environment and extremely low output have led to the high price of colored diamonds.

 

HPHT method (high pressure high temperature) and CVD method (chemical vapor deposition) are the current mainstream methods for synthesizing diamonds. Among them, CVD method has the advantages of simple growth equipment, fast growth rate, and high growth crystal, and is widely used in industrial diamond production.

 

At present, the preparation of colored diamonds is mainly pure color, and the color is relatively single. In order to improve the appreciation of colored diamonds, some researchers have carried out the synthesis of multi-color diamonds. For diamonds grown by MPCVD, whether it is gradient pink diamond or gradient blue diamond, the color is regulated by controlling the doping concentration of impurity gas during the growth of diamond. This method has high requirements for the airtightness of the equipment, and it is easy to cause obvious stratification of diamonds, cracking in the subsequent processing of diamonds, reducing the yield of diamonds and affecting their prices.

 

The method of preparing CVD blue gradient diamonds based on lead electron irradiation carriers of the present invention is implemented according to the following steps:

• S1, pre-treating diamond seed wafers;
• S2, plasma etching seed crystals;
• S3, introducing methane and hydrogen into the vacuum chamber to perform microwave plasma chemical vapor deposition growth;
• S4, obtaining diamond blanks;
• S5, cutting off the polycrystalline on the surface of the diamond blanks;
• S6, HPHT treatment of the cut blanks;
• S7, placing the diamond blanks on the bottom plate of the irradiation carrier, and using high-energy electron beams to irradiate the shielding cavity and the diamond blanks.

 

The present invention places the diamond blank in a special irradiation carrier to irradiate a part of the diamond blank, prepare a blue diamond with a gradient color, and improve the purity of the diamond. The irradiation carrier is made of metal lead, and the irradiation carrier includes a bottom plate and a shielding cavity, which is arranged on the upper surface of the bottom plate and has an open side.

 

The present invention belongs to the field of diamond color change and provides an effective method for color gradient diamond.

 

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