Structural study of a Ag3.4In3.7Sb76.4Te16.5 quadruple compound utilized for phase-change optical disks - art. no. 184116

The behavior of a quadruple compound, Ag3.4In3.7Sb76.4Te16.5, is investigat ed at various temperatures using the large Debye-Sherrer camera installed i n BL02B2 at SPring-8, to elucidate its crystal structure. The low-temperatu re phase of this crystal has an A7 structure with atoms of Ag, In, Sb, or T e randomly occupying the 6(c) site in the R(3) over bar m space group. The crystal lattice thermally expands almost linearly with increasing temperatu re between 81 K and around 850 K. The crystal structure shows little change between 81 K and around 600 K however, above 600 K, marked changes with in creased temperature are observed with respect to the thermal vibration of a toms, interatomic distances and bond angles. The A7 structure transforms at approximately 780 K to a rhombohedral structure that includes only one ato m in each unit cell. This change of structure is thought to be a second-ord er phase transition. The compound A(93.4)In(3.7)Sb(76.4)Te(16.5) can mainta in its crystalline phase up to approximately 850 K, but at higher temperatu res it changes into an amorphous phase.