Novel superstructure of the rocksalt type and element distribution in germanium tin antimony tellurides

作者：Rosenthal Tobias; Welzmiller Simon; Neudert Lukas; Urban Philipp; Fitch Andy; Oeckler Oliver^*

来源：Journal of Solid State Chemistry, 2014, 219: 108-117.

DOI：10.1016/j.jssc.2014.07.014

• Telluride
• Structure elucidation
• Nanostructures
• HRTEM
• Resonant scattering

A superstructure of the rocksalt-type observed in quenched CVT-grown single crystals of Ge3.25(7)Sn1.10(3)S1.10(3)Te6 was elucidated by X-ray diffraction using fourfold twinned crystals (space group P (3) over bar m1, a=4.280(1) angstrom, c=20.966(3) angstrom). The structure is built up of distorted rocksalt-type building blocks typical for long-range ordered GST materials and substitution variants thereof. In contrast to those phases, an exclusive ABC-type cubic stacking sequence of the Te-atom layers is present. High-resolution electron microscopy reveals spheroidal domains with this structure (average diameter 25 nm) whose stacking direction is perpendicular to the %26lt; 1 1 1 %26gt; directions of the basic rocksalt-type structure. Additional slab-like domains with a lateral extension up to 1 gm occasionally result in a hierarchical structure motif. Due to the similar electron counts of the elements involved, resonant diffraction was used in order to elucidate the element distribution in rocksalt-type building blocks of the stable layered compound 39R-Ge3SnSb2Te7 (R (3) over barm, a=4.24990(4) angstrom, c=73.4677(9) angstrom). Sb tends to occupy the atom site close to the van der Waals gaps while Ge concentrates in the center of the building blocks.

• 出版日期2014-11