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Structurally perfect diamond type Ib single crystals growth weighing 5 to 10 carats in six-press apparatus


Work number - M 41 AWARDED

Presented V. M. Bakul Institute of Superhard Materials

Authors:
PhD Burchenia A. V., Savitskyi O. V.

The aim of present work is to create a directional control system of growth parameters of diamonds and determine the conditions of their cultivation to obtain structurally perfect single type Ib diamond crystals weighing from 5 to 10 carats in a growth system based on Fe-Ni solvent using six-pistons cubic apparatus type CS-VII 6×28.5 MH.

Scientific bases of pressure and temperature measurement in the growth cells of a six-anvil high-pressure apparatus have been created. Loading characteristics of the CS-VII six-anvil growth cell loading have been determined to determine the pressure values up to 7 GPa at temperatures up to 1400 ºС. Characteristics allows to estimate the compression efficiency up to 500 GPa at 7–7 GPa ºС and 1150-1400 ºС with Fe-Co and Cu-Ag sensors using, respectively, as well as the suitability of using the growth cell materials and the configuration of the parts made from them.

The basic conceptual principles of obtaining a single crystal with the preservation of full-length forms during the whole cycle of cultivation by changing the thermal state of the growth cell was formulated. Base principles consists in the gradual increase of temperature at a rate of 0.3-1.0 ºC / h, starting from 80-100 h after the beginning of the growing process and maintaining a mass growth rate not higher than 3, 7 and 11 mg / h when reaching single crystal masses values 5, 7 and 10 carats, respectively.

Design of a container with a growth cell for single Ib type diamond crystal with mass from 5 to 10 carats cultivation on a single seed is proposed. Experimental-laboratory technology was developed for obtaining structurally perfect full-length crystals of cuboctahedral habit, with the possibility of varying the development of cubic / octahedral faces in the ratio (%) 10 / 90-70 / 30, as well as flattened plates of cubic habit. Systems have been developed and manufactured and put into operation control units for the growth of single crystals with cooling of CS-VII six-anvil press and the ability to work in automatic mode with growing cycles of up to 220 hours or more.

Comparison with the world analogues, the proposed directional control system allows to obtain samples of single crystals of diamond with the development of granular forms of high structural perfection.

The results of the research work were implemented at the company "Alkor–D" (Kyiv, Ukraine) and "Best" (Jinan, China).

The economic impact of the implementation can reduce production costs by 20-25% and increase the productivity of the cultivation process by 2.5–3 times.

 

Number of publications: 29, including 14 papers. According to Scopus base total number of authors publications –2, h–index=1; according to Scopus base total links – 5, h–index=1. Novelty and competitions of technical solutions protected by 7 patents.

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