Equipment for the growth of crystals at very high gas pressures

A fourteen-stage thermally-acting pistonless gas compressor (BGK-14) is described. The compressor allows non-reactive gases to be compressed to 6 kbar while completely avoiding contamination of the gas by impurities. A recurrence formula is provided which allows the distribution of gas pressures among the cylinders of the compressor to be calculated after an arbitrary heating cycle. The internal construction of the very high pressure working chamber is described, which is used together with a multiplicator and the compressor, and serves to compress the gas from 6 to 30 kbar. A method of growing single crystals of black phosphorus under conditions of high gas pressure, taking into account evaporation and subsequent transfer in the atmosphere of compressed gas, is considered. The single crystal plates grown have dimensions 4 X 6 mm; their thickness varies from 0.15 to 0.25 mm; they are opaque and in reflected light they have a characteristic metallic lustre; they are not affected by moisture. A method of growing, from aqueous solution in a similar apparatus, single crystals of barely soluble substances is described.