Investigation of the porous GaP layers' chemical composition and the quality of the tests carried out

2018 ◽  
Vol 2 (86) ◽  
pp. 49-60 ◽  
Author(s):  
S. Vambol ◽  
V. Vambol ◽  
Y. Suchikova ◽  
I. Bogdanov ◽  
O. Kondratenko
Keyword(s):  
Chemical Composition ◽  
Hydrofluoric Acid ◽  
Gallium Phosphide ◽  
Electrochemical Etching ◽  
Experimental Studies ◽  
Practical Significance ◽  
Standard Samples ◽  
Modern Material ◽  
Porous Semiconductors

Purpose: The purpose of this study is to establish the quality of tests for determining the chemical composition of the porous surface obtained by the method of electrochemical etching, based on the indicators of convergence and reproducibility of the results. Design/methodology/approach: The method of electrochemical etching was used to obtain layers of porous gallium phosphide, which can be used as buffer layers for nitrides formation on their basis. Por-GaP was formed in a solution of hydrofluoric acid at a current density of j =100 mA/cm2, etching was carried out for 20 minutes. The resulting structures sulfide passivation was carried out, thus avoiding the formation of an oxide film on the samples surfaces. For this purpose, porous gallium phosphide samples were kept in a sulfide solution for 10 minutes and dried in a stream of nitrogen. The chemical composition of the porous GaP surface layers has been investigated. To do this, the method of electronprobe INCA Energy microanalysis was used. The research was carried out on the entire surface of the sample in order to calculate the total spectrum of the elemental composition of the sample under study. Findings: It was established that during anodizing, the stoichiometry of the crystals investigated did not shift significantly towards the excess of gallium atoms. Oxygen is present at an insignificant concentration of 0.3%. This indicates the effectiveness of conducting the sulfide passivation of the sample surface following the electrochemical treatment. The presence of fluorine atoms that appeared on the surface as a result of the reaction with the electrolyte during etching, is observed in extremely low concentration. Experimental studies have shown that the sample chosen can be used as a standard enterprise sample when analyzing the chemical composition of the surface of porous gallium phosphide due to its convergence, reproducibility, homogeneity. In addition, the given method for determining the standard sample can be applied to other porous semiconductors. Conducting such studies is an important technological task that will allow us to create a series of standard samples of porous semiconductors of A3B5 group. Research limitations/implications: The research was carried out for porous gallium phosphide samples synthesized in the solution of hydrofluoric acid, though, carrying out of similar experiments for por-GaP obtained in other conditions, is necessary. Practical implications: The studies of the reproducibility and convergence of the experiment have an important practical significance, since it is the reproducibility of the experiment results that is the main problem to modern material science, all the more to nanoengineering. Therefore, the technique proposed, will allow the synthesis of por-GaP layers with adjustable properties, will facilitate their widespread implementation in the real sectors of industry. The obtained porous layers can be used as standard samples. Originality/value: The main problem in the nanostructures synthesis is the adjustability of properties. The technique presented allows to form stable layers of the porous gallium phosphide with the surface chemical composition known in advance. In addition, carrying out the sulfide passivation allows to stabilize por-GaP properties, which is an important process task. For the first time, a study of the presented technique as to convergence, reproducibility and homogeneity, was conducted.

scholarly journals COMPARATIVE ANALYSIS OF THE CHEMICAL COMPOSITION OF WATERWATER IN THE SLAVSKY DISTRICT OF THE KALININGRAD REGION BY HYDROLOGICAL SEASONS

2021 ◽  
Vol 31 (4) ◽  
pp. 425-436
Author(s):  
Yu.A. Spirin ◽  
S.I. Zotov ◽  
V.S. Taran ◽  
Yu.V. Koroleva
Keyword(s):  
Chemical Composition ◽  
Winter Season ◽  
Practical Significance ◽  
Anthropogenic Activity ◽  
Quality Of Water ◽  
Hydrochemical Data ◽  
Maximum Permissible Concentrations ◽  
Kaliningrad Region ◽  
Selection Of

The aim of the work is to research the chemical composition of surface watercourses in the Slavsky district of the Kaliningrad region in the winter hydrological season, and to compare the results with the data previously obtained by the authors for the autumn hydrological season and partly for the summer hydrological season. Watercourses and monitoring points for research have been identified: r. Zlaya, r. Shluzovaya, r. Nemoninka and r. Osa. In the winter season, water samples were taken, hydrometric characteristics were measured, and primary hydrochemical indicators were determined. On the basis of the obtained hydrochemical data, integral indicators were calculated to assess the quality of water, using combined lists of maximum permissible concentrations of pollutants. When monitoring hydrochemical indicators, it was revealed that the studied watercourses are, to one degree or another, subject to pollution. The water quality class in them varies from "moderately polluted" to "extremely dirty". When comparing the seasons, a tendency was revealed to improve the quality of water, which is associated with the water content of rivers, as well as with the cycles of natural and anthropogenic activity. The work has theoretical and practical significance. The data can participate in the planning of rational use of natural resources and the selection of measures to improve the geoecological state of the river network of the Slavsky region. The research can serve as a supplement to the formation of the general geoecological picture of the Kaliningrad region.

POROUS SILICON: INFLUENCE OF ETCHING TEMPERATURE ON MICROSTRUCTURE AND LUMINESCENCE

2001 ◽  
Vol 08 (05) ◽  
pp. 429-433 ◽  
Author(s):  
D. J. BLACKWOOD ◽  
Y. ZHANG
Keyword(s):  
Porous Silicon ◽  
Light Source ◽  
Hydrofluoric Acid ◽  
Uv Light ◽  
Electrochemical Etching ◽  
Light Emitting ◽  
Influence Of Temperature ◽  
Etching Solution ◽  
Experimental Parameters

Electrochemical etching in solutions based on hydrofluoric acid has been widely used to form light-emitting porous silicon. However, the effects of a number of the experimental parameters on the quality of the porous silicon produced have yet to be fully investigated. In the present paper the influence of temperature and viscosity of the etching solution is evaluated in terms of the morphology and porosity of the porous silicon produced as well as the wavelength of the photoluminescence or electroluminescence subsequently emitted. It was found that under stimulation from a UV light source the wavelength of the photoluminescence emitted from the porous silicon films blueshifted with decreasing etching temperature. SEM and AFM investigations revealed that this blueshifting of the photoluminescence resulted from the production of smaller nanocrystals at the lower etching temperatures.

scholarly journals “AGROHYDROCHEMISTRY” (2021) – A CONTRIBUTION TO THE IMPLEMENTATION OF THE PROVISIONS OF THE “NITRATE DIRECTIVE” 91/676 / EEC IN UKRAINE

2021 ◽  
pp. 74-80
Author(s):  
M.R. Zabokrytska
Keyword(s):  
Chemical Composition ◽  
Water Policy ◽  
Natural Waters ◽  
Agricultural Land ◽  
Experimental Studies ◽  
Water Bodies ◽  
The European Union ◽  
The World ◽  
The Impact

The article presents and analyzes the textbook “Agrohydrochemistry” (author V.K. Khilchevsky – professor of the Taras Shevchenko National University of Kyiv), published in 2021. The textbook examines the main problems associated with the growth of the chemicalization of agriculture and the protection of water resources. Due to agriculture, there is a noticeable impact on the quality of natural waters in the world, especially in regions of intensive agriculture, to which Ukraine belongs. Increased concentrations of nutrients and various types of pesticides are found in the waters of small and large rivers, groundwater. Therefore, the issues of studying the main sources of agricultural pollution of natural waters and the processes that contribute to this are relevant. Among the main sources of pollution of natural waters with wastewater, namely industrial, household and agricultural – the latter have a specific character of formation and flow into water bodies. If industrial and domestic wastewater is localized behind the formation and place of discharge into the sewer network, then the formation and supply of chemicals from agricultural land is dispersed throughout the catchment area and natural ways of entering (hydrographic network) into water bodies. The attention of the world community to the impact of agrochemicals on the quality of natural waters is evidenced by the Directive 91/676/EU adopted in the European Union of December 12, 1991 “On the protection of waters from pollution caused by nitrates from agricultural sources” (abbreviated as “Nitrogen Directive”), which in turn is a local manifestation of the integrating directive 2000/60/EC of October 23, 2000 “On the establishment of a framework for Community activities in the field of water policy” (abbreviated WFD – “EU Water Framework Directive”), aimed at achieving a good ecological state of natural waters in the regions river basins. Agrohydrochemistry is a direction in hydrochemistry that studies the effect of agrochemical agents on the chemical composition of natural waters using theoretical methods and the results of experimental studies in watersheds. The textbook, which consists of 9 chapters, gives an idea of the formation of the balance of chemicals in the soil, the use of various types of fertilizers and pesticides, and the possible ways of their entry into water bodies. Methods for calculating the flow of chemicals into water bodies are presented. The theoretical provisions are illustrated by the materials of our own research on the effect of agrochemicals on the chemical composition of river waters in the Dnieper basin. The textbook is designed for students of the specialty “Earth Sciences” of educational programs of the hydrological profile of higher educational institutions..

scholarly journals Influence of abrasive materials on the quality of analytical surfaces during preparation of samples for spectral analysis

2020 ◽  
pp. 112-116
Author(s):  
M. V. Lagoyskaya
Keyword(s):  
Spectral Analysis ◽  
Chemical Composition ◽  
Sample Preparation ◽  
Mass Fraction ◽  
Surface Preparation ◽  
Optical Emission ◽  
Sample Surface ◽  
Standard Samples ◽  
Materials Used

The article considers the possibility of contamination of the surface of steel samples with abrasive materials when preparing samples for determining the chemical composition on optical emission spectrometers.The standards for sample preparation methods describe in detail the methods of surface treatment, the materials used, and the requirements for the quality of the analyzed surface. The sample surface can be milled or sanded using various abrasive materials. In practice, the laboratory found that the surface of samples during sample preparation is contaminated with aluminum and calcium.In order to determine how the contamination of analytical surfaces occurs, the chemical composition of all materials used in the preparation of samples was studied, and an experiment was conducted to establish a method for preparing the sample surface that does not lead to contamination of the surface with aluminum and calcium. For the experiment, three standard samples of steel composition were selected with certified values of the mass fraction of aluminum and calcium in different ranges. The surface of each sample was processed in three ways and optical emission spectral analysis was performed on each analytical surface at five points to determine the value of the mass fraction of aluminum and calcium and to estimate the spread of the results obtained. As a result of tests it was found that by grinding the sample surface by using abrasive white corundum and abrasive paper grit P40 is the surface contamination of the analyzed sample in aluminum and calcium, therefore, when determining the mass fraction of aluminium and calcium in steel are required for surface preparation to use the method of milling.

scholarly journals INFLUENCE OF SORPTION-PROBIOTIC SUPPLEMENT BIOPINNULAR FOR PRODUCTIVITY, CHEMICAL COMPOSITION AND ECOLOGICAL PURITY OF BROILER CHICKEN MEAT

2021 ◽  
Vol 246 (2) ◽  
pp. 66-72
Author(s):  
O.A. Desyatov ◽  
◽  
L.A. Pykhtina ◽  
V.A. Isaychev ◽  
Yu.V. Semenova ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Chemical Composition ◽  
Broiler Chicken ◽  
Experimental Studies ◽  
Live Weight ◽  
The Body ◽  
Feed Additive ◽  
Scientific Article ◽  
Feed Conversion

The scientific article presents the material of experimental studies, in which it is stated that the use of the feed additive Biopinnolar in the feed additive for broilers in the amount of 0.5 and 1.0% of its weight, provides a more intensive increase in their live weight, better feed conversion, and reduces the toxicological load. on the body of young poultry, improves the chemical composi-tion and quality of their meat with less accumulation of heavy metals in it.

Behavior of Some Varieties in the Kernel Group to the Attack of the Main Pathogens

2018 ◽  
Vol 12 (2) ◽  
pp. 1-7
Author(s):  
Sînziana Venera Morărița
Keyword(s):  
Chemical Composition ◽  
Climatic Conditions ◽  
Complex Chemical ◽  
Complex Chemical Composition ◽  
Large Production ◽  
Special Quality

Abstract Although relatively recent, peach culture has grown great in our country due to the special quality of the fruit, its very complex chemical composition and the large production that can be obtained without much effort. Peach is a species slightly adapted to our climatic conditions, suffers from winter frost, but can provide productive and long productions of 10-15 years.

The system of indicators of the quality of the carbon-carbon composite materials and technologies of their production

2018 ◽  
pp. 127-132
Author(s):  
T. N. Antipova ◽  
D. S. Shiroyan
Keyword(s):  
Composite Material ◽  
Low Cost ◽  
Experimental Studies ◽  
Carbon Matrix ◽  
Carbon Composite ◽  
Optimal Number ◽  
Laboratory Equipment ◽  
Carbon Composite Material ◽  
Carbon Composite Materials

The system of indicators of quality of carbon-carbon composite material and technological operations of its production is proved in the work. As a result of the experimental studies, with respect to the existing laboratory equipment, the optimal number of cycles of saturation of the reinforcing frame with a carbon matrix is determined. It was found that to obtain a carbon-carbon composite material with a low cost and the required quality indicators, it is necessary to introduce additional parameters of the pitch melt at the impregnation stage.

scholarly journals Effect of NaCl Replacement by other Salts on the Quality of Bísaro Pork Sausages (PGI Chouriça de Vinhais)

Foods ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 961
Author(s):  
Alfredo Teixeira ◽  
Rubén Domínguez ◽  
Iasmin Ferreira ◽  
Etelvina Pereira ◽  
Leticia Estevinho ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Microbiological Quality ◽  
Sodium Content ◽  
Sensory Characteristics ◽  
Meat Industry ◽  
Important Goal ◽  
Salt Consumption ◽  
Oxidation Index ◽  
Pork Sausages

Concerned about the trend to reduce salt consumption, the meat industry has been increasing the strategies to produce and commercialize products where the reduction or even the replacement of NaCl is an important goal. The aim of this study was to test the effect of partial NaCl replacement by KCl and Sub4Salt® on the quality of pork sausages. Three different formulations (NaCl + KCl, NaCl + Sub4Salt®, and KCl + Sub4Salt®) were considered and compared to the control (2% NaCl). Physicochemical properties, chemical composition, and microbiological and sensory characteristics were evaluated. The replacement of NaCl did not affect pH, water activity (aw) or its chemical composition after eight or 16 days ripening time, while a significant sodium reduction was achieved. The oxidation index expressed in TBARS was also not affected by the NaCl substitution and varied between 0.01 to 0.04 of malonaldehyde (MDA) per kg of sample. Similarly, the NaCl replacement did not change the microbiological quality of the sausages, and the production of healthier meat sausages had also no significant effect on their sensory characteristics. Therefore, according to the results obtained, it is viable and a good strategy for the meat industry to produce “reduced sodium content” sausages without affecting their traditional quality.

scholarly journals Molecular Hydrogen Maintains the Storage Quality of Chinese Chive through Improving Antioxidant Capacity

Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1095
Author(s):  
Ke Jiang ◽  
Yong Kuang ◽  
Liying Feng ◽  
Yuhao Liu ◽  
Shu Wang ◽  
...  
Keyword(s):  
Antioxidant Capacity ◽  
Molecular Hydrogen ◽  
Practical Significance ◽  
Total Phenolic ◽  
Guaiacol Peroxidase ◽  
Storage Quality ◽  
Decay Index ◽  
Chinese Chive ◽  
Dpph Scavenging

Chinese chive usually becomes decayed after a short storage time, which was closely observed with the redox imbalance. To cope with this practical problem, in this report, molecular hydrogen (H2) was used to evaluate its influence in maintaining storage quality of Chinese chive, and the changes in antioxidant capacity were also analyzed. Chives were treated with 1%, 2%, or 3% H2, and with air as the control, and then were stored at 4 ± 1 °C. We observed that, compared with other treatment groups, the application of 3% H2 could significantly prolong the shelf life of Chinese chive, which was also confirmed by the obvious mitigation of decreased decay index, the loss ratio of weight, and the reduction in soluble protein content. Meanwhile, the decreasing tendency in total phenolic, flavonoid, and vitamin C contents was obviously impaired or slowed down by H2. Results of antioxidant capacity revealed that the accumulation of reactive oxygen species (ROS) and hydrogen peroxide (H2O2) was differentially alleviated, which positively matched with 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and the improved activities of antioxidant enzymes, including superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX). Above results clearly suggest that postharvest molecular hydrogen application might be a potential useful approach to improve the storage quality of Chinese chive, which is partially achieved through the alleviation of oxidative damage happening during the storage periods. These findings also provide potential theoretical and practical significance for transportation and consumption of perishable vegetables.

Sign in / Sign up

Export Citation Format

Share Document