Spectroscopic Ellipsometry Characterization of As-Deposited and Annealed Non-Stoichiometric Indium Zinc Tin Oxide Thin Film

A spectroscopic ellipsometry study on as-deposited and annealed non-stoichiometric indium zinc tin oxide thin films of four different compositions prepared by RF magnetron sputtering was conducted. Multi-sample analysis with two sets of samples sputtered onto glass slides and silicon wafers, together with the analysis of the samples onto each substrate separately, was utilized for as-deposited samples. Annealed samples onto the glass slides were also analyzed. Spectroscopic ellipsometry in a wide spectral range (0.2–6 eV) was used to determine optical constants (refractive index n and extinction coefficient k) of these films. Parameterized semiconductor oscillator function, together with Drude oscillator, was used as a model dielectric function. Geometrical parameters (layer thickness and surface roughness) and physical parameters (direct optical bandgap, free carrier concentration, mobility, and specific electrical resistivity) were determined from spectroscopic ellipsometry data modeling. Specific electrical resistivity determined from the Drude oscillator corresponds well with the results from electrical measurements. Change in the optical bandgap, visible especially for annealed samples, corresponds with the change of free carrier concentration (Moss–Burstein effect). Scanning electron microscope did not reveal any noticeable annealing-induced change in surface morphology.

Simultaneous effects of nano-silica and basalt fiber on mechanical properties and durability of cementitious mortar: An Experimental Study

This study investigated the single and hybrid effects of nanosilica and basalt fiber on mechanical properties, and durability of mortar. Results showed that basalt fiber could remarkably increase the indirect tensile strength, whereas the compressive strength and durability properties were not significantly improved by basalt fiber. However, incorporation of nanosilica in the mortar containing basalt fibers (NSB) could acceptably compensate for this weakness of basalt fiber-reinforced mortar (BF) and remarkably improve not only the compressive strength and durability but also the indirect tensile strength compared to BF samples. According to the best results, samples containing 1% of nanosilica and 0.05% of basalt fiber improved the compressive strength, sorptivity, and water absorption by 37, 48, and 32%, respectively. Moreover, incorporation of 1% of nanosilica and 0.125% of basalt fiber increased the flexural strength, splitting tensile strength, and specific electrical resistivity by 29, 27, and 35%, respectively, compared to the control samples.

Determination of the electrical resistivity of rocks by scanning method while searching and exploring hydrocarbon deposits

The article contains information on the determination of the specific electrical resistivity of rocks by scanning magnetotelluric sounding method while searching for and exploring hydrocarbon deposits.

ABOUT POSSIBILITY TO CLASSIFY COAL LAYERS HAZARDOUS CHARACTERISTICS BY GENETIC AND PROCESS PARAMETERS OF COALS

The analysis of Ukrainian legal environment has been performed for solid fossil fuels production, which has shown existing of contradictories between parameters describing the accuracy of forecast to manifest the coal layers hazardous characteristics during independent of mining and does not exclude any possibility for emergency situation to occur, independent of the preventive measures full implementation. The base to determine the coal layers hazardous characteristics are: average reflectance of vitrinite, presence of some components in organic matter (С0, О0, Н0, N0), alteration of moisture and mineral impurities content. For these classificatory parameters, their quantitative assessment is available in the whole multiplicity of coals metamorphic transformation. The specific electrical resistivity logarithm and other proxy parameters may serve as additional classificatory parameters to reveal any hazardous characteristics of anthracites after grounding their using in some ranges of metamorphism series. It has been established that the existing wide range of vitrinite reflectance alteration for anthracites specifies significant alterations in the fossil fuel structure and properties. In their process of metamorphism, these peculiarities of anthracite alterations have almost not been classificatory established by their genetic and process parameters.

ELECTRICAL AND ACOUSTIC PARAMETERS OF LOWER PERMIAN CARBONATE ROCKS (WESTERN PART OF THE HLYNSKO-SOLOKHIVSKYI OF GAS-OIL-BEARING DISTRICT OF THE DNIEPER-DONETS BASIN)

The main objective of this article is to study electrical parameters of Lower Permian carbonate rocks of Western part of the Hlynsko-Solokhivskyi gas-oil-bearing district of the Dnieper-Donets Basin (DDB) in normal (atmospheric) and modeling (reservoir) conditions. In atmospheric conditions it has been revealed that the resistivity of dry extracted limestones (the specific electrical resistivity of framework of grains was measured) varies from 12.147 kΩ⋅m to 111.953 MΩ⋅m (mean 1.542 MΩ⋅m). The resistivity of saturated limestone samples with kerosene varies from 44.478 kΩ⋅m to 14.449 MΩ⋅m (mean 1.435 MΩ⋅m). The resistivity of dry and saturated with kerosene samples is almost the same. The resistivity of limestones saturated with model of reservoir water (salinity M = 190 g/l) is lower and varies from 1.11 Ω⋅m to 23.16 Ω⋅m (mean 3.12 Ω⋅m). It has been determined that formation resistivity factor of limestones in atmospheric conditions varies from 13.5 to 230 Ω⋅m (mean 32.5 Ω⋅m). In addition to resistivity, the parameter of relative permittivity of investigated limestones was studied. It was determined that relative permittivity of dry limestones varies from 3.0 to 7.5 (mean 4.2). Relative permittivity saturated samples of limestones with kerosene varies from 2.8 to 8.8 (mean 4.5) and practically does not differ from dry ones but significantly lower than values of samples saturated with model of reservoir water (from 655 to 9565, mean 4280). That means when pores of limestones are saturated with NaCl solution their relative permittivity increases rapidly – from hundreds to thousands times (on average 944 times). It can be explained by the high conductivity of model of reservoir water. Limestones saturated with NaCl solution have velocities of P-waves in the range from 3346 m/s to 4388 m/s (mean 4030 m/s), and velocities of Swaves – from 1753 m/s to 2121 m/s (average 1942 m/s). If rocks are saturated with kerosene then velocities have strictly higher values – P-waves from 3433 m/s to 4514 m/s (mean 4011 m/s) and S-waves – from 2137 m/s to 2464 m/s (average 2344 m/s). Physical modelling of reservoir conditions (temperature 50 °С, pressure 30 MPa) showed that the specific electrical resistivity varies from 0.81 Ω⋅m to 13.19 Ω⋅m (mean 2.67 Ω⋅m), and limestones – from 0.49 Ω⋅m to 7.81 Ω⋅m (mean 1.95 Ω⋅m). Also, "specific electrical resistivity – pressure" connection was investigated. Due to the closure of microcracks and the deformation of the pore space, the electrical resistance of rocks increases with increase of pressure. The regression dependence of the formation resistivity enlargement factor with pressure for the studied rocks has a linear character. It was determined that in reservoir conditions the range of the formation resistivity factor for limestones varied from 17.3 to 271.9 Ω⋅m (mean 50.7 Ω⋅m), and range of variation of porosity coefficient was from 0.040 to 0.169 Ω⋅m (mean 0.118 Ω⋅m). The comprehensive analysis of petrophysical data has been resulted in a set of correlation ratios between reservoir, electric and elastic parameters of studied limestones in normal and modeling conditions.

The influence of salinity on acoustic and electrical properties of frozen soils

The results of determining acoustic and electrical properties of frozen saline soils (sand and silt) of massive cryogenic texture at different water content (3 values for each type of soil), salinity (7 values for silt and 5 for sand) and temperatures (–2, –4, –6 ᵒC) are given in the article. As a result, data on the high correlation between specific electrical resistivity and concentration of the pore solution and between ratio of a concentration of the pore solution to temperature and the velocity of longitudinal waves were obtained. Electrical resistivity can decrease by 2–22 times during the transition from a low-saline to a highly saline state and for longitudinal wave velocities only two times. Therefore, it is the electrical properties that are most suitable for the ranking of soils by the degree of salinity.

ELECTRICAL PARAMETERS OF THE UPPER CARBON ROCKS (RUNOVSHCHYNSKA AREA OF THE DNIEPER-DONETSK BASIN)

The main objective of this article is to study electrical parameters of sandstones and argillites of the Upper Carbon rocks in the Runovshchynska area of the Dnieper-Donets basin. It has been determined that specific electrical resistivity of dry rock samples (specific electrical resistivity of rock matrix) varies from 44,802 kΩ·m to 6,115 МΩ·m (average 751,328 kΩ·m). Specific electrical resistivity of sandstones is 3,45 times more than argillitesdue to different shaliness of studied rocks. Specific electrical resistivity of saturated rocks samples varies from 0,54 Ω·m to 10,46 Ω·m (average 1,23 Ω·m). Specific electrical resistivity of argillites is 2,46 times more than sandstones because the latter had high content of reservoir water in their pores (sandstones had better conductivity). It has been determined that formation resistivity factor of sandstones in atmospheric conditions varies from 6,05 to 33,71 (argillites 11,8), and argillites – from 4,76 to 51,47 (average 17,4). Physical modelling of reservoir conditions (temperature t = 78,5°С, pressure p = 31–31,9 MPa, mineralization M= 170 g/l) showed that specific electrical resistivity varies from 0,3 Ω·m to 3,0 Ω·m (average 0,75 Ω·m). Sandstones in reservoir conditions had the range from 0,3 Ω·m to 2,3 Ω·m (average 0,7 Ω·m), and argillites – from 0,5 Ω·m to 3,0 Ω·m (average 1,2 Ω·m). In this case, specific electrical resistivity of argillites is 1,6 times more than sandstones. Due to the closure of microcracks and the deformation of the pore space, the electrical resistance of rocks increases with increasing pressure. The dependence of formation resistivity enlargement factor on pressure for the studied rocks is expressed by 2-order polynomials. The formation resistivity factor of the studied rocks in reservoir conditions has been determined. It was defined that sandstones in reservoir conditions had the range of the formation resistivity factor from 5,4 to 63,3 (average 20,3), and porosity coefficient – from 0,038 to 0,175 (average 0,113). The range of the formation resistivity factor for argillites was from 13,4 to 88,7 (average 34,3), and porosity coefficient – from 0,043 to 0,115 (average 0,086). Analysis of data of laboratory electrometric investigations has allowed establishing correlations between the porosity coefficient and formation resistivity factor. In addition, the correlation of electrical parameters of rocks in atmospheric and reservoir conditions and the formation resistivity enlargement factor from the water saturation coefficient, taking into account the lithological varieties of the studied rocks, was established.