Colloidal synthesis of Sb2S3 nanorods/bars with strong preferred orientation

We report the synthesis of antimony trisulfide (Sb₂S₃) nanorods/bars via a simple, low-cost and colloidal synthetic method. The as-synthesized Sb₂S₃ nanorods/bars with different heating times from the moment of appearance of the Sb₂S₃ precipitate at 240 °C are the longest and thinnest in the beginning (diameters of 50-100 nm and lengths of 3-5 μm). UV/Vis absorption spectroscopy reveals that the optical band gap energy of the Sb₂S₃ nanorods/bars slightly decreases with increasing the heating times in the range of 1.54, 1.50 to 1.47 eV at the red part of the solar spectrum. The structure of Sb₂S₃ for all free samples was refined down to the R-factor of 9.57, 5.43 and 6.19%. The refinement showed that Sb₂S₃ powder belongs to the orthorhombic type with space group Pbnm (no. 62). It was found that Sb₂S₃ nanorods/bars predominantly grow along the [010] direction. The preferred orientation parameter (τ) refined against experimental data is quite high and is found to be 1.42, 1.21 and 1.19 for all three samples observed. A decrease in unit cell parameter b followed by increasing the heating times was observed.     

Growth of Sb2S3 nanowires synthesized by colloidal process and self-assembly of amorphous spherical Sb2S3 nanoparticles in wires formation

We report the organic synthesis and growth of antimony sulfide (Sb₂S₃) amorphous nanospheres to nanowires via a simple, colloidal synthetic method. Amorphous Sb₂S₃ nanospheres self-assembly in wires formation was dispersed in isopropyl alcohol. With increased heating time, Sb₂S₃ nanospheres grew into Sb₂S₃ nanowires, probably involving both mechanisms of Ostwald-ripening and spherical nanoparticle self-organization through oriented-attachment of individual nanoparticles. Also, the as-synthesized Sb₂S₃ nanowires with different heating times (0, 5 and 10 min.) from the moment of appearance of the Sb₂S₃ precipitate were analyzed. The observed nanowires become longer with increased heating time and are around 100 nm in diameter and 10?C20 ??m in length. UV-Vis absorption spectroscopy reveals that the optical band-gap energy of the Sb₂S₃ nanowires is independent of the heating times and is found to be ??1.5?C1.6 eV. The optical band-gap energy found for amorphous Sb₂S₃ nanospheres was also ??1.5 eV. The structure of Sb₂S₃ samples was refined down to R-factors of 10.82, 11.76 and 12.08%. The refinement showed that Sb₂S₃ powder belongs to the orthorhombic type with space group Pbnm (no. 62) and that Sb₂S₃ nanowires grow along the [010] direction.     

Efficient and novel Sb2S3 based solar cells with chitosan/poly(ethylene glycol)/electrolyte blend

We present here a novel solar cell made of ITO/composite p‐doped Sb₂S₃ + P3HT + PANI+TiO₂/amorphous Sb₂S₃ + P3HT + PANI + TiO₂/n‐doped Sb₂S₃ + P3HT + PANI + TiO₂/solid carrier/aluminum as counter electrode. With spraying technique, the layers were deposited and the thickness of films was 1 μm. A new solid carrier of electrolyte was a blend consisted of chitosan (low MW), polyethylene glycol and electrolyte. X‐ray diffraction was recorded to confirm the amorphous nature of the blend. Information about the surface appearance and roughness of a solid carrier dry and soaked in the electrolyte was given by atomic force microscopy. The solar cell was examined at very low and low light intensity (5% and 35% of sun, respectively), and at standard test conditions (100% of sun) using different light sources. The whole cell surface was 7.5 cm² while the illuminated part was 3 cm². Obtained results expressed for the illuminated surface showed the highest efficiency of 23.1% at 5% of sun while the efficiency of the cell was 2.9% at 35% of sun and only 0.75% at intensity of 100% of sun.     

Effect of lateral earth pressure on the limit load and settlement of the sand base of a plate

The results of a model experiment on loading the sand base of a plate with preassignment of various lateral earth pressures are examined. An increase of lateral earth pressure reduces the limit load on the base and under loads exceeding the initial critical load causes an increase of settlement of the plate. The reliability of the result obtained in the experiment is proved by a numerical analysis of the limit stress state at a point.Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 3, pp. 8–10, May–June, 1992.     

Synthesis,strong room-temperature PL and photocatalytic activity of ZnO/ZnWO4 rod-like nanoparticles

Zinc oxide (ZnO)/zinc tungstate (ZnWO₄) rod-like nanoparticles with diameters in the range of 6–11 nm and length of about 30 nm were synthesized by a low temperature soft solution method at 95 °C in the presence of non-ionic copolymer surfactant. It was found that their crystallinity was enhanced with the increase of heating time from 1 h up to 120 h. The photoluminescence (PL) measurements showed very strong, narrow UV band peaked at 3.30 eV and a broad visible band peaking at 2.71 eV with a shoulder at about 2.53 eV, for λ_exc < 300 nm. Quite large variations in the intensities of the two PL bands were observed for different excitation wavelengths. The intensity of the main visible band decreases with decreasing excitation energy and disappears when samples are excited λ = 320 nm (E_exc = 3.875 eV). We found that observed optical properties originate from ZnO phase. UV band gap PL had high intensity for all applied excitations, probably induced by ZnWO₄ phase presence on the surface. In addition, two values were found for direct band-gap energy of ZnO/ZnWO₄ rod-like nanoparticles 3.62 and 3.21 eV, determined from reflectance spectrum. The photocatalytic behaviour of ZnO is strongly dependent on the formation of ZnWO₄ phase, of the obtained rod-like nanoparticles.     

On Lagrange-Euler formulations for fluid-structure interactions

A new nonlinear Lagrange-Euler (LE) variational principle is presented for fluid-structure interaction problems. The functional is entirely dual for the fluid and for the shell structure. The stress unknowns exactly satisfy the equilibrium equation. After having recalled and completed some variational principles in Lagrangian coordinates, the new LE principle is given, followed by stability criteria.     

Growth and quantum confinement in AgI nanowires

Silver iodide nanowires were synthesized in W/O microemulsions by using cyclohexane/Triton X-100/n-pentanol system. Most likely, surfactants form rod-like aggregates that can serve as template for growth of two dimensional nanomaterials. It was found that the length of the AgI nanowires increases as a function of aging time, while the diameter decreases. Final length of the AgI nanowires is several microns, while the diameter is smaller than 3 nm. Morphological changes are accompanied by optical and structural changes. Large blue shift of excitonic peak from bulk value at 420 to 326 nm was observed as a consequence of the size quantization effect. Decrease of diameter is followed by the amorphization of AgI nanowires.     

Organic Synthesis with Different OA/EHA Ratios of Sb<Subscript>2</Subscript>S<Subscript>3</Subscript> Nanowires of Flower-Like Organization and [010] Orientation

We report the first time as-synthesized antimony trisulfide (Sb₂S₃) nanowires with flower-like organization by using different oleic acid (OA)/2-ethylhexanoic acid (EHA) ratio. The resulting optical band-gap energy is 1.6 eV, and it is independent of the OA/EHA ratios. Sb₂S₃ nanowires grow predominantly along the [010] direction, and a significant decrease in unit cell parameters was observed. It seems that the shorter branched hydrocarbon chain leads to the better structural stability of the synthesized Sb₂S₃ nanowires.