Phase Relations in the System Ni-S-Se at 500 degrees C.

The Real (Incommensurate Interface Modulated) Structure of Ni6±xSe5

“…These compounds are only thermodynamically stable over a limited temperature interval (400}570 and 450}6703C for the sul-"de and selenide, respectively (8)) and are reported to be isotypic (6). The phase can, however, be stabilized to room temperature either via rapid quenching or appropriate chalcogenide substitution (8,9). The average structure of the phase has been reported to be orthorhombic Bmmb with cell dimensions a&3.4, b&17.1, and c&11.9 A > in the case of the selenide and a&3.3, b&16.4, and c&11.3 A > in the case of the sul"de (9,10,12).…”

“…The phase can, however, be stabilized to room temperature either via rapid quenching or appropriate chalcogenide substitution (8,9). The average structure of the phase has been reported to be orthorhombic Bmmb with cell dimensions a&3.4, b&17.1, and c&11.9 A > in the case of the selenide and a&3.3, b&16.4, and c&11.3 A > in the case of the sul"de (9,10,12). (The parent re#ections corresponding to this average structure unit cell are labeled G in what follows).…”