Cold crucible system and method for the meeting and crystallization of non-metallic inorganic compounds

Claim 1

A cold crucible system for melting and crystallizing a non-metallic inorganic compound comprising a crucible having a wall section and a bottom (3), said wall section being formed of hollow metal pipes having a cooling medium flow therethrough said pipes being mechanically connected to said bottom for providing flow of said cooling medium through said bottom; a first inductance coil surrounding the wall section of said crucible, a second induction coil, independently switchable of said first induction coil and positioned below the bottom of said crucible, both of said induction coils providing a coupling of high frequency energy into any non-metallic inorganic compound present in said crucible and providing a melt of said compound in said crucible, wherein said crucible contains a member (11) of an electrically conductive material, rapidly heatable by induced eddy currents and inert to any melt (21) present in said crucible, positioned at a distance above the bottom (3) of said crucible and a container (23) consisting of a material inert to melt (21) present in said crucible, open in the direction opposite to that of the bottom of said crucible, provided with apertures (33, 39, 43) for passage of said melt and being of such a capacity and so positionable in relation to the wall section and the bottom of said crucible so as to contain up to 25% of the overall contents of said non-metallic inorganic compound present in said crucible while having an upper edge projecting from said crucible and means connected to said container for vertically moving said container in and out of said crucible.

Claim 19

A method of growing single crystals of rare earth metal gallium garnets from melts thereof said method comprising, (a) placing a rare earth gallium garnet powder into a crucible having a wall formed of hollow metal pipes through which a cooling medium flows, and a bottom mechanically connected to said pipes to allow flow of said cooling medium through said bottom, inductive coil means for independently coupling high frequency through said wall and said bottom into said powder, a member (11) of an electrically conductive material, rapidly heatable by induced eddy currents and inert to melt of said powder positioned at a distance above the bottom of said crucible and a container (23) consisting of a material inert to said melt, open at the top and provided with apertures (33, 39, 43) for passage of said melt, and being vertically positionable within said melt so as to contain up to 25% of said melt while projecting from said melt; (b) inductively heating said powder through said inductive coil means to thereby form a melt of said garnet in said crucible; (c) lowering said container (23) into said melt to a depth such that the upper edge of said container projects from the melt and it is filled, by flow through said apertures, of up to 25% of the melt present in said crucible; (d) contacting a crystal of said garnet with said melt present in said container (23) while slowly decreasing the content of high frequency energy coupled to said melt in said container (23) thereby slowly cooling said melt in said container (23) and causing crystal growth of said melt to occur in said container.

Claim 20

A method of growing single crystals of rare earth metal gallium garnets from melts thereof said method comprising, (a) placing a rare earth gallium garnet powder into a crucible having a wall formed of hollow metal pipes through which a cooling medium flows, and a bottom mechanically connected to said pipes to allow flow of said cooling medium through said bottom, inductive coil means for independently coupling high frequency through said wall and said bottom into said powder, a member (11) of an electrically conductive material, rapidly heatable by induced eddy currents and inert to melt of said powder positioned at a distance above the bottom of said crucible and a container (23) consisting of a material inert to said melt, open at the top and provided with apertures (33, 39, 43) for passage of said melt, and being vertically positionable within said melt so as to contain up to 25% of said melt while projecting from said melt; (b) inductively heating said powder through said inductive coil means to thereby form a melt of said garnet in said crucible; (c) lowering said container (23) into said melt to a depth such that the upper edge of said container projects from the melt and it is filled, by flow through said apertures, of up to 25% of the melt present in said crucible; (d) contacting a crystal of said garnet with said melt present in said container (23) while slowly decreasing the content of high frequency energy coupled to said melt in said container (23) thereby slowly cooling said melt in said container (23) and causing crystal growth of said melt to occur in said container.