| 摘要 |
In a process for growing a single crystal by melting and then cooling material in a closed quartz or other vitreous vessel, where the vapour pressure of the material (e.g. the semiconducting phosphors zinc sulphide, cadmium sulphide and <PICT:0923241/III/1> zinc selenide) when molten would burst the vessel which is soft at the melting point of the crystal-forming material, the vessel is enclosed in a close-fitting crucible of refractory material, the crucible and vessel are heated initially at a rapid rate so that the vessel is raised above its softening point before the crystal-forming material develops substantial vapour pressure, and heating is continued to melt the enclosed material. The material 1 is placed in a quartz tube 2 which is evacuated, sealed and inserted in a graphite crucible 4, space between the tube 2 and crucible 4 being filled with graphite powder. The crucible is then placed in a carbon tube having thick-walled ends 8 and a thin-walled central portion 9. Electric current is passed through the carbon tube to heat it and soften the quartz tube 2, which then expands until stopped by the graphite crucible 4. Further heat is applied until the material 1 is molten, and then the temperature is gradually reduced to allow the melt to solidify to form the crystal. |
