The toroid-type high-pressure-high-temperature apparatus is described.
It is rather simple in design and operation and allows to generate
pressures in the range of 9-12 GPa with a working volume of 1-0.3 cm3.
The advantages of this apparatus are its convenience for introducing a
fluid-filled capsule and numerous electrical leads in the
high-pressure region and reliable operation of these leads. It makes
possible measurements of electric, thermal, magnetic and volume
properties of matter in a hydrostatic environment at room and elevated
temperatures as well as material synthesis experiments. The recent
developements in this field are the strain gauge technique for presise
quantitative measurements of volume of solids to 9 GPa and the
sensitive differential thermal analysis technique for studies of the
second order magnetic transitions in antiferromagnetic insulators.
Methods of introducing fluid-filled capsule in the other types of high
pressure apparatus (piston-cylinder, belt, multianvil) to attain
hydrostatic pressures above 5 GPa are discussed. The use of toroid
high pressure device in the so called "Paris-Edinburg Cell" for
neutron studies above 10 GPa is briefly reviwed. The examples of
experimental studies of phase transitions in semiconductors, magnetics
and amorphous solids with the use of toroid apparatus are given. A
variety of toroidal cells developed in the Institute for High Pressure
Physics, RAS and adapted for different applications includes devices
in the range from large (few cm3 sample volume, 6-7 GPa, 2000 K, few
sousands ton-force press capacity) to small (1 mm3 sample volume, 12
GPa, 4.2-300 K, miniature clamp-type 20 ton-force press). It makes
possible to solve a wide spectrum of problems in physics, chemistry,
geoscience and material science at high pressure.