Температурная зависимость ширины запрещенной зоны монокристаллов AgIn7S11

AgIn7S11 single crystals are herein grown by the vertical Bridgman method. The composition of the obtained single crystals is determined by X-ray microprobe analysis as well as the crystal structure – by X-ray diffraction analysis. It is shown that the obtained single crystals are crystallized in the cubic spinel structure. Using transmission spectra in the tem- perature range 10–320 K we determined the band gap of these single crystals and plotted its temperature dependence. This dependence is similar to that of the majority of semiconductor materials, namely, Eg increases with decreasing the tempera- ture. We showed the agreement of the calculated and experimental values.Вертикальным методом Бриджмена выращены монокристаллы AgIn7S11. Методом рентгеноспектрального анализа определен их состав, рентгеновским методом – кристаллическая структура. Показано, что полученные монокристаллы кристаллизуются в кубической структуре шпинели. По спектрам пропускания в интервале температур 10–320 К определена ширина запрещенной зоны указанных монокристаллов и построена ее температурная зависимость. Данная зависимость имеет вид, характерный для большинства полупроводниковых материалов: с понижением температуры Eg возрастает. Показано, что расчетные и экспериментальные величины согласуются между собой

Temperature dependence of AgIn13S20 single crystal band gap

AgIn13S20 single crystals were grown by the vertical Bridgman method. The grown crystals composition was determined by X-ray spectroscopy analysis; the crystal structure was determined by X-ray method. It was shown, that AgIn13S20 compound crystallize in the cubic spinel structure. The band gaps of the obtained single crystals were estimated from transmittance spectra in the temperature range of 10-320 K. The band gap values decreased with temperature

Photocatalytic destruction of tetracycline hydrochloride on surface of titania dioxide films modified by gold nanoparticles

Films of titania (TiO2) and titania modified with gold nanoparticles (TiO2:Au) were synthesized by a sol–gel method on substrates of glass, aluminum, and aluminum with a layer of nanotextured aluminum or porous anodic alumina. The photocatalytic activity of the samples was investigated in an aqueous solution of the antibiotic tetracycline hydrochloride (TC). TC decomposition was observed in the presence of all samples as a reduction of the solution optical density in the range below 500 nm. Titania was in the crystalline anatase phase with incorporated spherical gold nanoparticles primarily of sizes 1–10 nm after heat treatment at 400°C. Modification of TiO2 films with gold nanoparticles on glass or aluminum substrates did not increase the photocatalytic activity of the samples. It was found that complexes of TC with Al3+ in solution formed only in the presence of gold nanoparticles in the film either in the dark or with UV irradiation

Optical characteristics of strontium titanate films formed by sol-gel method on quartz substrates

The transmission spectra of films of strontium titanate up to 200 nm thick produced on quartz glass substrates by the sol-gel method were investigated in the region of 200–1100 nm. The sol was prepared from strontium acetate, titanium tetraisopropoxide, acetic acid, and ethylene glycol monomethyl ether. The strontium titanate films were formed by successive deposition of five layers with intermediate drying of each layer and final heat treatment at temperatures in the range of 500–700oC. From analysis of the transmission spectra it was established that the obtained films are characterized by a wide forbidden band decreasing from 4.46 to 3.84 eV in the transition from x-ray amorphous films to crystalline films with refractive index of 1.996 (λ = 620 nm) due to the high packing density of up to 81.5% of that for monocrystalline strontium titanate

Temperature dependence of the band gap of AgIn8S12.5 single crystals

Вертикальным методом Бриджмена выращены монокристаллы AgIn8S12.5. Методом рентгеноспектрального анализа определен состав полученных монокристаллов, методом рентгеновской дифракции — кристаллическая структура. Показано, что выращенные монокристаллы кристаллизуются в кубической структуре шпинели. По спектрам пропускания в интервале температур 10 − 320 K определена ширина запрещенной зоны, которая с понижением температуры возрастает. AgIn 8 S 12.5 single crystals were grown by the vertical Bridgman method. The composition of the single crystals was determined by the X-ray spectral analysis method, and the crystal structure was determined by the X-ray diffraction method. It is shown that the grown single crystals crystallized in the cubic spinel structure. Transmittance spectra in the temperature range 10 − 320 K were used to determine the band gap of the crystals, which increased with decreasing the temperature