Apparatus and method for isolation of diamond seeds for growing diamonds

A process for the production of diamond material comprising the steps of:

• pressurizing a reaction vessel containing a diamond seed material and a source of carbon separated by a mass of catalyst-solvent to a pressure in the diamond stable region of the phase diagram of carbon said seed material, carbon source and catalyst-solvent being positioned in stacked relationship within said reaction vessel;
• while simultaneously heating said reaction vessel in such a manner to create within said vessel a temperature gradient in said diamond stable region such that the diamond seed material is at a temperature near the minimum temperature of said gradient and said source of carbon is at a temperature near the maximum temperature of said gradient, whereby a temperature gradient is created between said seed material and carbon source;
• and limiting diamond growth adjacent the diamond seed material until the catalyst-solvent material is saturated with carbon under the operating conditions and until a diamond growth pattern is initiated upon said seed material and established in said carbon saturated mass of catalyst-solvent by interposing an isolation barrier in the reaction vessel between said diamond seed material and said mass of catalyst-solvent prior to said pressurizing and heating step, said isolation barrier being substantially inert to the reaction vessel and its contents at said operating conditions and has at least one opening therein between said diamond seed material and said mass of catalyst-solvent at said operating conditions to define a restricted diamond growth path having an equivalent cross-sectional diameter in the range of 0.001 to 0.020 inches, said diamond growth proceeding freely in said mass of catalyst-solvent, and maintaining said operating conditions until a diamond of at least 14 mgm is grown.

In a process for the production of diamond material comprising the steps of:

• (i) providing a reaction vessel containing a diamond seed material and a source of carbon separated by a mass of catalyst-solvent for the diamond making process;
• (ii) providing means for applying high temperature and high pressure to said reaction vessel;
• (iii) inserting said reaction vessel in said means for applying high temperature and high pressure;
• and
• (iv) subjecting said reaction vessel to operating conditions of temperature and pressure in the diamond stable region of the phase diagram for carbon to create a predetermined temperature gradient in said reaction vessel in a manner such that said diamond seed material is at a temperature near the minimum value of temperature for the temperature gradient at substantially the same time said source of carbon is at a temperature near the maximum value of temperature for said temperature gradient;
• the improvement in said process comprising the step of interposing in the reaction vessel between said diamond seed material and said mass of catalyst-solvent before the reaction vessel is inserted in said means for applying high temperature and high pressure, a layer substantially inert to and insoluble in the molten catalyst-solvent at said operating conditions and having at least one opening in said layer between said diamond seed material and said mass of catalyst-solvent at said operating conditions to provide a restricted diamond growth path and provide a discrete seeding site to the mass of catalyst-solvent remote from said seed material and disposing in said opening a solid wire of a catalyst-solvent material for the diamond-making reaction.

Apparatus for the production of diamond materials comprising:

• a reaction vessel containing a diamond seed material and a source of carbon separated by a mass of catalyst-solvent, said seed material, carbon source and catalyst-solvent being arranged in stacked relationship within said vessel;
• means for pressurizing said vessel to a pressure in the diamond stable region of the phase diagram for carbon;
• means for heating said vessel, contemporaneously with pressurization, in such a manner to create a temperature gradient in said diamond stable region within said vessel such that the diamond seed material is at a temperature near the minimum of said gradient and said source of carbon is at a temperature near the maximum temperature of said gradient, whereby a temperature gradient is created between said seed material and carbon source;
• and a solid barrier layer defining a restricted growth path opening having a solid wire of a catalyst-solvent material for the diamond-making process disposed therein and interconnecting said mass of catalyst-solvent and a volume containing said diamond seed material, said layer being selected from the group consisting of NaCl, CaF.sub.2, refractory oxides, natural mica, high melting point silicate glasses not reduced by hot carbon, and porcelain, said layer limiting diamond growth adjacent the diamond seed material until the catalyst-solvent material is saturated with carbon, under the operating conditions of the diamond-making process and until a diamond growth pattern has developed from said seed material to said carbon saturated mass of catalyst-solvent, such as to control the size of the diamond growth presented thereto said diamond growth proceeding freely in said mass of catalyst-solvent, whereby a diamond of at least 14 mgm is grown.

In an apparatus for the production of diamond material comprising:

• (i) a reaction vessel containing a diamond seed material and a source of carbon separated by a mass of catalyst-solvent for the diamond-making process;
• (ii) means for heating said vessel to a temperature in the diamond stable region of the phase diagram for carbon and to create a predetermined temperature gradient in said reaction vessel such that said diamond seed material can be maintained at a temperature near the minimum value of temperature for the temperature gradient at substantially the same time said source of carbon is at a temperature near the maximum value of temperature for said temperature gradient;
• and
• (iii) means for applying high pressure for operating said reaction vessel in the diamond stable region of the phase diagram for carbon;
• the improvement comprising:
• (iv) a layer in said reaction vessel interposed between said diamond seed material and said mass of catalyst-solvent, said layer being a solid barrier being substantially inert to and insoluble in the molten catalyst-solvent, and defining a restricted diamond growth path between said seed material and mass of catalyst-solvent such as to provide a discrete seeding site to the mass of catalyst-solvent remote from said seed material, said restricted growth path having disposed therin a solid wire of a catalyst-solvent material for the diamond-making process.