Sumitomo Electric Industries, Limited

Kazuo Tsuji

Shuji Yazu

Akio Hara

Katsuhito Yoshida

Akito Yoshida

Synthesis of diamond by the so-called thin solvent film method is improved to obtain diamond crystals with a large grain size and good quality in an economical manner. To this end, using a reaction system comprising diamond seed crystal, a carbon source and a solvent metal, one or more masses of the solvent metal are arranged independently of each other and the diamond seed crystals are arranged in such a manner that one surface of the diamond seed crystal is contacted with each solvent metal mass.

Method of synthesizing diamond

An artificial diamond single crystal, at least a part of a surface of the crystal having a rough surface which diffusibly reflects light which is formed by suppressing crystal growth at that surface, and wherein said diamond single crystal is obtained by:

Diamond single crystal

A diamond synthesizing method carried out under diamond-stable superhigh pressure and temperature by employing a synthesizing vessel (10) having a plurality of synthesizing chambers (10a, 10b) divided by a partition layer (16) in the vertical direction. Solvent metals (13a, 13b) respectively placed in the upwardly arranged synthesizing chamber (10a) and the downwardly arranged synthesizing chamber (10b) are prepared so that the solvent metals are different in eutectic temperature with carbon from each other. In the respective synthesizing chambers (10a, 10b), carbon sources (12a, 12b) are placed in contact with highest-temperature portions of the respective solvent metals (13a, 13b) and seed crystals (11a, 11b) are placed in contact with lowest-temperature portions thereof. The synthesizing vessel (10) is provided with a temperature gradient in such directivity that the upper part thereof is at a higher temperature and the lower part is at a lower temperature.

An artificial diamond single crystal, a process for producing it, and tools for utilizing it are disclosed. The artificial diamond crystal has at least one surface which has a rough surface formed by suppressed crystal growth at that surface. The single crystal is produced by providing a diamond synthesis reaction system comprised of a reaction chamber, a carbon source and a solvent metal arranged in contact with the carbon source. A seed crystal is provided in the reaction chamber under elevated pressures and temperatures which permit diamond to be maintained thermodynamically stable. The reaction system is heated to provide a temperature gradient in such a way that a portion of the solvent metal in contact with the carbon source is higher in temperature than a portion of the solvent metal in contact with the seed crystal. This temperature gradient causes a migration of the carbon from the higher temperature portion to the lower temperature portion using the solvent metal as a medium. This allows the carbon to precipitate and grow as diamond on the seed crystal due to the difference in solubility caused by the temperature gradient. The conditions in the reaction chamber housing are maintained so as to suppress crystal growth in at least one direction perpendicular to the direction of the temperature gradient, at the end of the solvent metal. The suppressed crystal growth provides the rough surface of the single crystal which can be connected to a tool and thus provides good adherence between the crystal and the tool.

Diamond single crystals, a process of manufacturing and tools for using

The invention relates to a diamond sintered compact wherein diamond crystal particles are uniformly orientated in a particular direction and the method for producing the same, and has for an object to provide a diamond sintered compact having a high thermal conductivity particularly suitable for heat sink for use in the field of electronics. According to the invention, graphite is used as carbonaceous raw material, diamond crystal particles having such elongated shape that the ratio of the length of the long axis to that of the short axis is more than 2 being synthesized in such state that the greater part of the crystal particles have their long axes uniformly oriented in a particular direction, the crystal particles being sintered in the direction of the long axes thereof so that transformation of the graphite into diamond and sintering thereof may be accomplished synchronously. The invention has for an object to obtain a diamond sintered compact suitable for the aforesaid use by degassing reaction system raw material plugged into an air permeable container by heating it in vacuum in order to intercept gaseous components causing a decrease of thermal conductivity at the time of synthesizing diamond from carbonaceous material and a catalytic metal and sintering thereof, subsequently the air permeable part of the said container being sealed by means of soldering material preliminarily placed in contact with the said container.

Diamond sintered compact wherein crystal particles are uniformly

The invention relates to a diamond sintered compact wherein diamond crystal particles are uniformly oriented in a particular direction and the method for producing the same, and has for an object to provide a diamond sintered compact having a high thermal conductivity particularly suitable for heat sink for use in the field of electronics. According to the invention, graphite is used as carbonaceous raw material, diamond crystal particles having such elongated shape that the ratio of the length of the long axis to that of the short axis is more than 2 being synthesized in such state that the greater part of the crystal particles have their long axes uniformly oriented in a particular direction, the crystal particles being sintered in the direction of the long axes thereof so that transformation of the graphite into diamond and sintering thereof may be accomplished synchronously. The invention has for an object to obtain a diamond sintered compact suitable for the aforesaid use by degassing reaction system raw material plugged into an air permeable container by heating it in vacuum in order to intercept gaseous components causing a decrease of thermal conductivity at the time of synthesizing diamond from carbonaceous material and a catalytic metal and sintering thereof, subsequently the air permeable part of the said container being sealed by means of soldering material preliminarily placed in contact with the said container.

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Hyogo, Japan

Kazuo Tsuji