Features of technological synthesis and properties of ZnO-Cd based materials for photocatalytic applications. Review

In this review, the current state of ZnO-Cd based materials for photocatalytic applications is summarized. Relevant technological synthesis methods such as pulsed laser deposition, magnetron sputtering, electrodeposition, sol-gel, metalorganic chemical vapor deposition, evaporating, spray pyrolysis, reflux are considered, and recent developments in effective and reproducible synthesis technology of nano- and microstructured zinc oxide, doped with cadmium and solid solutions of Zn1‑xCdxO for photodecomposition of organic pollutant molecules are discussed. The synthesis technology and level of Cd doping has a significant effect on the structure and morphology of zinc oxide and, as a result, on the optical and photocatalytic properties. The figures of merit, the theoretical limitations and rational control of the concentration of the cadmium alloying impurity is necessary to create a material with balanced optical properties and photocatalytic activity. Lastly, the importance of doping ZnO by isovalent Cd impurity significantly improves its photocatalytic properties due to a narrowing of the band gap, a decrease in the rate of recombination of electron-hole pairs, which increases the efficiency of spatial charge separation, the formation of active oxide radicals and an increase in the specific surface area. Thus, ZnO-Cd based materials are the most promising photocatalytic materials for organic pollutants

Аналіз ринку препаратів для консервативного лікування геморою з метою визначення маркетингових можливостей для вітчизняного виробника

The spread of diseases of the rectum, namely hemorrhoids, leads to the deterioration of the physical and psychological health of the working-age population, increases the budget costs of the healthcare system, insurance companies, and the population’s own funds. In this regard, the development of new complex medicinal products is always relevant for domestic pharmacy. Aim. To form a modern idea of the market structure and trends in the consumption of drugs for the conservative treatment of hemorrhoids, determine the possible potential for domestic developers and manufacturers. Materials and methods. The research was conducted using the structural analysis logical and graphic methods, methods of marketing analysis. Results. It was found that recently the market of antihemoroidal agents for topical application and capillary-stabilizing agents developed quite vigorously – the market growth rates in the period of 2020-2021 were from 15 to 23 % in physical units and from 28 to 40 % in monetary units. However, according to the structure of the producing countries, the market remains import-dependent. Drugs from France, Switzerland, Bulgaria, Germany, Spain, Slovenia, Italy, and the United States are available on the market. The leaders of sales are products manufactured by Servier (France), Innotek International (France), and Teva (Israel). The leaders in the supply of domestic drugs of this group are Borshchagovsky Chemical Pharmaceutical Plant, JSC “Galichpharm”, Kyiv Vitamin Plant, PJSC “Darnitsa” Pharmaceutical company”, PJSC “Monpharm”. The most popular dosage forms are tablets, capsules, gels, ointments, suppositories. Conclusions. Based on the changes identified, certain proposals have been developed for the domestic pharmaceutical industry – the market has a relatively small range of domestic complex medicines combining components of chemical and natural origin, including the plant raw material. The market has a positive development trend; therefore, further search for an effective complex drug is expedient.Поширення захворювань прямої кишки, а саме геморою, призводить до погіршення фізичного й психологічного здоров’я працездатного населення, підвищує витрати з бюджету  системи охорони здоров’я, страхових компаній та власних коштів населення. У зв’язку із зазначеним  розроблення нових комплексних лікарських засобів залишається завжди на часі для вітчизняної фармації. Мета – формування сучасного уявлення про структуру ринку та тенденції споживання препаратів для консервативного лікування геморою, визначення можливого потенціалу для вітчизняних розробників і виробників. Матеріали та методи. Дослідження проведено за допомогою структурного аналізу, з використанням логічного й графічного методів, методів маркетингового аналізу. Результати дослідження. Виявлено, що останнім часом ринок антигемороїдальних засобів для місцевого застосування і капіляростабілізувальних засобів розвивався достатньо енергійно – темпи зростання ринку в період 2020-2021 рр. склали від 15 до 23 % у натуральних одиницях та від 28 до 40 % у грошових. Однак за структурою країн-виробників ринок залишається імпортозалежним. На ринку присутні препарати Франції, Швейцарії, Болгарії, Німеччини, Іспанії, Словенії, Італії, США. Лідерами продажів є засоби виробництва фірми Серв’є (Франція), Іннотек Інтернасіональ (Франція), Тева (Ізраїль) тощо. Лідерами постачання вітчизняних препаратів цієї групи є Борщагівський ХФЗ, АТ «Галичфарм», Київський вітамінний завод, ПАТ «Фармацевтична фірма “Дарниця”», ПАТ «Монфарм». Найбільш популярними формами випуску є таблетки, капсули, гелі, мазі, супозиторії. Висновки. На базі виявлених змін розроблено певні пропозиції для вітчизняної фармацевтичної індустрії – ринок має відносно незначний асортимент вітчизняних комплексних лікарських засобів, що поєднують компоненти хімічного та природного походження, зокрема й рослинну сировину. Ринок має позитивну тенденцію розвитку, тому подальший пошук ефективного комплексного препарату є доцільним

X-Ray Photoelectron Spectroscopy Study of Nitrogen and Aluminum-Nitrogen Doped ZnO Films

Undoped, nitrogen-doped and aluminum-nitrogen co-doped ZnO films were deposited on Si substrates by magnetron sputtering using layer-by-layer method of growth. X-ray photoelectron spectroscopy was employed to characterize electronic properties of undoped and nitrogen doped ZnO films. The effects of N and N-Al incorporation into the ZnO matrix on the X-ray photoelectron spectroscopy core-level and valence-band spectra of the films were studied and discussed

Detector with High Internal Photocurrent Gain Based on ZnO:N

The photoresponsive structures prepared by magnetron sputtering of ZnO:N on p-Si substrates followed by vacuum evaporation of semi-transparent Ni film on ZnO surface were investigated. The mentioned structures show high sensitivity that sharply enhances with increase of applied voltage. Under a bias 5 V, the responsivities at λ = 390 and 850 nm are equal to 210 A/W and 110 A/W which correspond to the quantum efficiencies of 655 and 165, respectively. It is suggested that the observed high response is attributed to internal gain in phototransistor structure containing Ni/n-ZnO Schottky contact as emitter junction and n-ZnO/p-Si heterostructure as collector junction

Detector with High Internal Photocurrent Gain Based on ZnO:N

The photoresponsive structures prepared by magnetron sputtering of ZnO:N on p-Si substrates followed by vacuum evaporation of semi-transparent Ni film on ZnO surface were investigated. The mentioned structures show high sensitivity that sharply enhances with increase of applied voltage. Under a bias 5 V, the responsivities at λ = 390 and 850 nm are equal to 210 A/W and 110 A/W which correspond to the quantum efficiencies of 655 and 165, respectively. It is suggested that the observed high response is attributed to internal gain in phototransistor structure containing Ni/n-ZnO Schottky contact as emitter junction and n-ZnO/p-Si heterostructure as collector junction

Copyright: Elsevier

Microstructure and luminescence dynamics of ZnCdO films with high Cd content deposited on different substrates by DC magnetron sputtering metho

Microstructure and luminescence dynamics of ZnCdO films with high Cd content deposited on different substrates by DC magnetron sputtering method

Investigation of Cd behavior in the ZnCdO alloys, where Cd content exceeds the solubility limit, is of importance due to possible impurity segregation and second phases' formation in this material. We have studied the Cd behavior in the Zn1-xCdxO films deposited by dc magnetron sputtering on different substrates: c-plane Al2O3, bare Si (1 0 0) and Au (45 nm)/Si (1 0 0). It is revealed that Cd content of 10 at. % in the target results in average 6-8 at. % of Cd in the films, depending on the substrate type. Structural analysis based on X-ray diffraction revealed the absence of Cd-related secondary phases. Time-resolved photoluminescence (TRPL) and high-resolution energy dispersive X-ray analysis (EDX) help to understand the recombination dynamics of spontaneous emission and to establish correlations between cadmium content and radiative lifetime. We have revealed that the internal quantum efficiency is influenced by the Cd content and defect concentration. It is suggested that increasing of the cadmium content results in the reduction of nonradiative recombination centers originating from point defects

Microstructure and luminescence dynamics of ZnCdO films with high Cd content deposited on different substrates by DC magnetron sputtering method

Investigation of Cd behavior in the ZnCdO alloys, where Cd content exceeds the solubility limit, is of importance due to possible impurity segregation and second phases' formation in this material. We have studied the Cd behavior in the Zn1-xCdxO films deposited by dc magnetron sputtering on different substrates: c-plane Al2O3, bare Si (1 0 0) and Au (45 nm)/Si (1 0 0). It is revealed that Cd content of 10 at. % in the target results in average 6-8 at. % of Cd in the films, depending on the substrate type. Structural analysis based on X-ray diffraction revealed the absence of Cd-related secondary phases. Time-resolved photoluminescence (TRPL) and high-resolution energy dispersive X-ray analysis (EDX) help to understand the recombination dynamics of spontaneous emission and to establish correlations between cadmium content and radiative lifetime. We have revealed that the internal quantum efficiency is influenced by the Cd content and defect concentration. It is suggested that increasing of the cadmium content results in the reduction of nonradiative recombination centers originating from point defects

Electrical properties of n-Zn0.94Cd0.06O/p-SiC heterostructures

We report the low-temperature (250 °C) fabrication of n-ZnCdO/p-SiC heterostructures by direct current magnetron sputtering (DC MS) technique. As-grown heterostructures exhibit diode characteristics: current–voltage measurements showed a typical rectifying characteristic of a p–n junction and the presence of series resistance. It is found that the turn-on voltage of heterostructures depends on the acceptor concentration in p-SiC. Via Cd doping of ZnO the energy barrier for holes can be lowered, which promotes the hole injection from the p-type layer to the n-type layer as well as favors the radiative recombination in the n-ZnCdO layer

Optical and electrical properties of highly doped ZnO:Al films deposited by atomic layer deposition on Si substrates in visible and near infrared region

Optical properties of ZnO films doped by Al in the range 0.5 to 7 at.% and deposited by atomic layer deposition were studied in visible and infrared spectral range. Spectral dependences of film optical permittivity were modeled with the Lorentz-Drude approximation resulting in ZnO:Al plasma frequency and plasma damping parameters. We observed changing electron effective mass from 0.29m₀ to 0.5m₀ with increasing electron concentration in the range (0.9-4) × 10²⁰ due to the phenomenon of conduction band non-parabolicity. Comparing the results of optical and electrical investigations we can see that the main scattering mechanism is the scattering on grain boundaries (its contribution is about 60%)