A low-temperature apparatus for single-crystal diffractometry. The unit-cell dimension of α-quartz in the temperature range 86–298 K

A detailed description of an automatic low-temperature apparatus to be used in single-crystal diffractometry is given. The crystal is cooled by a stream of nitrogen gas. Prevention of ice formation on the crystal is achieved by heating the outer parts of the gas stream by a conical metal device. The unit-cell dimensions of α-quartz have been determined in the temperature range 86–298 K with this apparatus on a four-circle diffractometer of type CAD-4.