BARS apparatus
BARS (or "split sphere") is a high-pressure high-temperature apparatus usually used for growing or processing minerals, especially diamond. The name is a transliteration of a Russian abbreviation БАРС = Беспрессовая Аппаратура высокого давления "Разрезная Сфера" (press-free high-pressure setup "split sphere"). Typical pressures and temperatures achievable with BARS are 10 GPa and 2500°C.[1]
The BARS technology was invented around 1989–1991 by the scientists from the Institute of Geology and Geophysics of the Siberian branch of the Academy of Sciences of the USSR.[1] In the center of the device, there is a ceramic cylindrical reaction cell of about 2 cm3 in size. The cell is placed into a cubic-shaped pressure-transmitting material, which is pressed by elements made from cemented carbide (VK10 hard alloy).[2] The outer octahedral cavity is pressed by 8 steel sectors. After mounting, the whole assembly is locked in a disc-type barrel with a diameter ~1 meter. The barrel is filled with oil, which pressurizes upon heating; the oil pressure is transferred to the central cell. The central cell is heated up by a coaxial graphite heater. Temperature is measured with a thermocouple.
The growth rate for 5 carats (1.0 g) type Ib (yellow, nitrogen-rich) crystals using Fe–Ni catalyst reaches as high as ~20 mg/h towards the end of 100 h growth cycle, i.e. crystals of 5 carats (1.0 g) to 6 carats (1.2 g) can be grown in less than 100 h.[3]
See also
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