Neutron diffraction investigation of the structural transition in HgSe1-xSx ternary mercury chalcogenide systems at high pressures

The structure of HgSe1-xSx ternary mercury chalcogenides at high pressures up to 35 kbar is investigated by neutron diffraction. It is found under pre ssure, that the HgSe1-xSx compounds undergo, a phase transition from the cu bic sphalerite-type to the hexagonal cinnabar-type structure, which is acco mpanied by a jumpwise change in the unit cell volume and interatomic distan ces. The unit cell parameters and the positional parameters of Hg and Se (S ) atoms in the high-pressure hexagonal phase are determined. A two-phase st ate is revealed in the phase transition region. (C) 2001 MAIK "Nauka/Interp eriodica".