- © 2000 Mineralogical Society of America
Knowledge of crystal structures at high temperatures is essential for our understanding of energetics, processes, and behavior of solid state materials. It is of particular importance in geophysics, because most mineralogical processes take place at conditions other than in air at room temperature. In order to study these mineralogical processes under conditions relevant to nature or to maintain the oxidation state or stability of a phase during study, scientists have designed various furnaces and environmental cells. Much of the early development of high-temperature devices for powder diffraction studies took place during the 1960s. Most of the construction materials we use today to build furnaces and environmental cells were available at that time, but digital computers for sophisticated diffractometer control and temperature control did not exist. The development of single-crystal heaters thus followed the development of automated single-crystal diffractometers, although some heaters were developed for camera work prior to this. New types of high-brilliance X-ray and neutron sources and new energy-dispersive and positional detector designs have allowed new device designs that were not previously possible. Hazen and Finger (1982) provided a review of single-crystal heaters and Chung et al. (1993) reviewed some devices that were developed to study powder crystalline materials at high temperature with X-ray diffraction.
The choice of the device to be used for an in situ diffraction experiment depends on the desired range of temperature and other environmental parameters. Generally, as the conditions of the experiment become more extreme, the constraints on sample changing, alignment and stability increase. It is often best to keep the device as simple as possible in order to facilitate the ease of use and the dependability of the apparatus consistent with the range of conditions that is required. In our experience, the temperature and stability claims made about various furnaces give the maximum …