Characterization of tin selenides synthesized by high-energy milling
Tin selenides SnSeX (x=1,2) were synthesized from tin and selenium powder precursors by high-energy milling in the planetary ball mill Pulverisette 6 (Fritsch, Germany). The orthorhombic tin selenide SnSe and the hexagonal tin diselenide SnSe2 phases were formed after 4 min and 5 min of milling, respectively. Specific surface area of both selenides increased with increasing time of mechanochemical synthesis. The particle size distribution analysis demonstrated that the synthesized products contain agglomerated selenide particles consisting of numerous idiomorphic tin selenide crystals, measuring from 2 to more than 100 nm in diameter, which were also documented by TEM. UV-Vis spectrophotometry confirmed that tin selenide particles do not behave as quantum dots.
Synthesis of binary copper chalcogenides by mechanical alloying
Copper sulfides (tetragonal Cu{sub 1.92}S-Cu{sub 1.99}S, rhombohedral Cu{sub 1.71}S-Cu{sub 1.89}S, CuS) selenides ({beta} Cu{sub 2{minus}x}Se, Cu{sub 3}Se{sub 2}, {gamma} CuSe, CuSe{sub 2}), and tellurides (Cu{sub 2{minus}x}Te, Cu{sub 3}Te{sub 2}) were prepared from mixtures of the elements by mechanical alloying (MA), using a high-energy ball mill. The compounds were obtained by 60--120 min of MA. It is notable that two metastable high-pressure phases were obtained by MA: tetragonal Cu{sub 2{minus}x}S and pyrite-type CuSe{sub 2}. The tetragonal phase gradually transformed to the stable phase of djurleite when kept at room temperature. Cu{sub 1.71}S-Cu{sub 1.89}S also formed a metastable rhombohedral phase.
A new simple technique to obtain In2Se3 polycrystalline thin films
Abstract In 2 Se 3 coatings were obtained either by direct evaporation of the compound in powder form or by solid state reaction, induced by annealing, between the In and Se constituents sequentially deposited in thin film form. The films have been investigated using X-ray diffraction, scanning electron microscopy, microprobe analysis, X-ray photoelectron spectroscopy and transmission electron microscopy. The effects of the starting material (compound powder or components sequentially deposited) have been studied. For thin Se and In films sequentially deposited, the effect of the variation of the In/Se atomic ratio, the annealing conditions—temperature, time, under selenium pressure or not—have been used as parameters. It is shown that thin films with a single phase and a high orientation degree can be obtained under appropriate annealing conditions, i.e. the layers sequentially deposited should be in the atomic ratio In/Se = 2/3 and they should be annealed under selenium atmosphere for 24 h at 573 K.