Abstract
X-ray diffraction and electrical resistance have been measured for amorphous and crystalline Te1-xSex mixtures (0≤ x≤ 1) under high pressure up to 30, GPa, and four high pressure phases of Te-Se mixtures have been observed: a monoclinic phase with 6 atoms per unit cell (M-I phase); a monoclinic phase with 4 atoms per unit cell (M-II phase); an orthorhombic phase; a β-Po-type phase. It was found for the first time that the M-II phase containing -- 60, at.\diffraction, EXAFS (extended X-ray absorption fine structure) and optical reflectivity have been measured for the pressure-quenched Te0.4Se0.6 specimens. Pressure-quenched Te0.4Se0.6 belongs to the space group Cm and has a puckered layer structure containing planer zigzag chains with period 3. Moreover, the superlattice structure with a unit cell size of 9 lattice constants along the b-axis was found. The EXAFS results suggest the existence of chemical short range order. We discuss the correlation between the structure and the electronic states in the high-pressure phases of Te-Se mixtures.
