The aim of the present work was to determine the compressibility and to characterize briefly the room-temperature phase transition from the sphalerite to the cinnabar structure under high-pressure conditions for various Hg_1-xZn_xSe mixed crystals. High quality Hg_1-xZn_xSe crystals were grown at the Institute of Physics of the Polish Academy of Sciences in Warsaw using the modified Bridgman method. The phase analysis and compositions of these samples were determined by the X-ray diffraction using conventional X-ray powder diffractometer. In analysed mixed crystals from a few to about 20% of Hg atoms were replaced by Zn atoms.
Energy-dispersive X-ray powder diffraction experiments were carried out at the F2.1 synchrotron beamline at DESY - HASYLAB. The beam diameter was equal to 100 mm. High-pressures were obtained at a cubic-anvil X-ray diffraction device, MAX80. The measurements were performed in the pressure range from 1 bar to 35 kbar at the ambient temperature.
The mixed crystal composition-dependent shift of the phase transition was clearly observed. The zinc-blende phase existed in relatively low-pressure range (up to ~7.5 kbar in the case of pure HgSe and up to ~20 kbar in the case of the highest mixed crystal composition under investigation). A comparison of the properties of magnetic and nonmagnetic mixed crystals grown on the basis of HgSe was discussed.


This work was partially supported by the IHP-Contract HPRI-CT-1999-00040/2001-00140 of the European Commission and by the grant 72/E-67/SPUB-M/DESY/P03/DZ-213/2000 from the State Committee for Scientific Research (Poland).