Structural transformation of Sb-based high-speed phase-change material.

The crystal structure of a phase-change recording material (the compound Ag(3.4)In(3.7)Sb(76.

Crystallization of the chalcogenide compound Sb8Te3.

The crystallization of a sputtered Sb(8)Te(3) film was examined in an X-ray powder diffraction experiment. An as-sputtered, amorphous Sb(8)Te(3) film crystallized during heating into a structure of Sb-Te homologous series modulated along the stacking direction. During heating the lattice parameters and the modulation period γ were found to change significantly and continuously; this observation suggests a continuous change in the stacking sequence.

Structural investigation of GeSb6Te10 and GeBi6Te10 intermetallic compounds in the chalcogenide homologous series.

The crystal structures of GeSb(6)Te(10) and GeBi(6)Te(10) were scrutinized using an X-ray powder diffraction method, which revealed that these compounds crystallize in trigonally distorted cubic close-packed structures with a 51-layer period (R3m). Each layer consists of a triangular atomic net; Te atoms occupy their own specific layers, whereas Ge, Sb and Bi atoms are located in the other layers. In these pseudobinary compounds, random atomic occupations of Ge and Sb/Bi are observed and the layers form two kinds of elemental structural blocks by their successive stacking along the c axis.

Structures of stable and metastable Ge2Bi2Te5, an intermetallic compound in a GeTe-Bi2Te3 pseudobinary system.

Ge(2)Bi(2)Te(5) in the GeTe-Bi(2)Te(3) pseudobinary system has two single-crystalline phases: a metastable phase with an NaCl-type structure and a stable phase with a nine-layer trigonal structure. In the metastable phase, the structure consists, in the hexagonal notation, of infinitely alternating stacks of Te and Ge/Bi layers at equal intervals along the c axis. On the other hand, in the stable phase those two layers are stacked alternately nine times to form an NaCl block.

Single structure widely distributed in a GeTe-Sb2Te3 pseudobinary system: a rock salt structure is retained by intrinsically containing an enormous number of vacancies within its crystal.

GeTe(1-x)-Sb2Te3(x) sputtered amorphous film was crystallized into a simple NaCl-type structure through instantaneous laser irradiation over a wide composition range from x = 0 to at least 2/3. When the ratio of Sb2Te3 increases, a vacancy is generated at every Na site for two Sb atoms. The fraction of vacancies, v(x), changes according to x/(1 + 2x), and the cubic root unit cell volume varies with a strong correlation to v(x).

Extremely long period-stacking structure in the Sb-Te binary system.

The crystal structure of the delta-phase in the Sb-Te binary system has been determined by synchrotron powder diffraction. It is clearly shown that many intermetallic compounds, which have different stacking periods depending on compound composition, exist in this phase. These structures are based on the cubic ABC stacking structure, and two kinds of fundamental structural units form an intergrowth along the stacking direction at the atomic level.