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323 results on '"Pogrebnjak, Alexander"'

1. Enhancement of piezoelectric response in V doped LiNbO3 films deposited by RF magnetron sputtering

Author

Zeng, Xiaomei, Lv, Ting, Zhang, Xiangyu, Zeng, Zhong, Yang, Bing, Pogrebnjak, Alexander, Pelenovich, Vasiliy O., and Liu, Sheng

Subjects
Condensed Matter - Materials Science, Physics - Chemical Physics
Abstract

LiNbO3 films doped with vanadium (V) were deposited using RF magnetron sputtering technique. To realize doping with a wider range of V concentration, a 30 mm V metal inlaid target asymmetrically embedded in the 150 mm lithium niobate target was used. The V concentration in the deposited films was a decreasing function of the distance from the V target. The V/Nb ratio decreased from 0.155 to 0.024, corresponding to a change in the composition of thin films from LiNb0.866V0.134O3 to LiNb0.977V0.023O3, respectively. Surface and inner morphology and structure, phase and element composition, microstructure, and ferroelectric properties of the undoped and V doped LiNbO3 films were studied. The measured maximal d33 constant of the LiNb0.935V0.065O3 film was about three times higher than that of the undoped LiNbO3 film, 14 pC/N and 4.76 pC/N, respectively. The optimal composition in the deposition geometry used was within the range of LiNb0.885V0.115O3 to LiNb0.952V0.048O3. Undoped and V doped LiNbO3 thin films were used as bulk acoustic wave ultrasonic transducers deposited on stainless steel plates to generate longitudinal waves and compare their ultrasonic performance., Comment: 20 pages, 9 figures

Published
2024

3. Novel electrically conductive electrospun PCL-MXene scaffolds for cardiac tissue regeneration

Author

Diedkova, Kateryna, Husak, Yevheniia, Simka, Wojciech, Korniienko, Viktoriia, Petrovic, Bojan, Roshchupkin, Anton, Stolarczyk, Agnieszka, Waloszczyk, Natalia, Yanko, Ilya, Jekabsons, Kaspars, Čaplovičová, Maria, Pogrebnjak, Alexander D., Zahorodna, Veronika, Gogotsi, Oleksiy, Roslyk, Iryna, Baginskiy, Ivan, Radovic, Marko, Kojic, Sanja, Riekstina, Una, and Pogorielov, Maksym

Published
2024
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4. AlCrO protected textured stainless steel surface for high temperature solar selective absorber applications

Author

Pelenovich, Vasiliy, Zeng, Xiaomei, Liu, Yan, Zhang, Xiangyu, Liu, Huidong, Pogrebnjak, Alexander, Vildanov, Ramil', Yang, Bing, and Liu, Sheng

Subjects
Physics - Chemical Physics, Condensed Matter - Materials Science
Abstract

The diffusion of substrate material into absorbing layer and oxidation of metal substrate or cermet metal nanoparticles at high temperatures are known as inevitable problems of the solar selective absorbers. In this study, we consider the use of textured stainless steel (SS) surface coated with a protective AlCr oxide layer as a high temperature solar selective absorber. The textured SS surface was prepared by ion etching techniques and AlCr oxide protective layer was deposited by RF magnetron sputtering. The absorptivity and emissivity of the as-prepared absorbers were 0.86-0.92 and 0.151-0.168, respectively. In order to evaluate the thermal stability, the absorbers were annealed at 600-800 C for different time in ambient atmosphere. Absorbers demonstrated a red shift of the onset of the reflectivity at all annealing temperatures. The high activation energy of 315 kJ/mol was calculated. The service lifetime of the absorbers at 500 C was estimated to be about 100 years and at 700 and 800 C the absorbers were stable about 50 and 1 hours, respectively. A detailed examination of the annealed absorber surface revealed growth of surface Mn3O4 nanocrystals, which resulted in observed change of the reflectance spectra, while the textured surface morphology had no significant change. The results show that the protective textured surface has much higher thermal stability in air than iron based cermet absorbers., Comment: 10 pages, 6 figures

Published
2021
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10. Exploring new pathways to enhance high entropy alloys properties

Author

Șerban Beatrice – Adriana, Cursaru Laura – Mădălina, Badea Ioana – Cristina, Piticescu Radu Robert, and Pogrebnjak Alexander

Subjects
Engineering (General). Civil engineering (General), TA1-2040
Abstract

For decades, conventional alloys represented the main pillar of engineering applications. However, their performances reach the limit when it faces tough demanding environments. High-entropy alloys (HEAs) meet this important challenge by leveraging the concept of entropy to achieve a unique combination of properties. This scientific paper presents the HEAs coatings, exploring their general characteristics and the exciting possibilities they offer, then the focus will be on HEA coatings, analysing their advantages and potential applications. Finally, the discussion will be held on the modelling techniques used to understand and predict the behaviour of these type of alloys.

Published
2024
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15. Research on the Influence of Matrix Shape on Percolation Threshold Values for Current Flow Conducted Using the Monte Carlo Simulation Method.

Author

Bondariev, Vitalii, Okal, Pawel, Rogalski, Przemyslaw, Pogrebnjak, Alexander, and Zukowski, Pawel

Subjects
MONTE Carlo method, DISTRIBUTION (Probability theory), GAUSSIAN distribution, STANDARD deviations, PERCOLATION
Abstract

In this study, in order to determine the effect of matrices' shape on the percolation threshold values, computer simulations were performed using the Monte Carlo method for a 200 × 200 square-shaped matrix and rectangular matrices containing the same number of nodes as the square matrix. Based on the simulations, the average values of the percolation thresholds and standard deviations for the current flow along and across the matrices were determined. It was determined that for a square-shaped matrix, the average values of the percolation thresholds in both directions of the current flow were the same. Extending the rectangular matrix while reducing its height causes the average value of the percolation threshold in the direction of the current flow along the matrix to increase from 0.592740 to 0.759847, while in the transverse direction, it decreases from 0.592664 to 0.403614. The values of the classical asymmetry coefficients of the probability distributions of the percolation thresholds for both directions of the current flow were determined. Histograms of the probability distributions of the percolation threshold values for a square-shaped matrix and rectangular matrices were made and compared with the normal distributions. It was found that the occurrence of two percolation thresholds in rectangular layers should be considered when analyzing the electrical conductivity measurements of nanocomposite thin films. [ABSTRACT FROM AUTHOR]

Published
2024
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22. Structural Particularities, Prediction, and Synthesis Methods in High-Entropy Alloys.

Author

Caramarin, Stefania, Badea, Ioana-Cristina, Mosinoiu, Laurentiu-Florin, Mitrica, Dumitru, Serban, Beatrice-Adriana, Vitan, Nicoleta, Cursaru, Laura-Madalina, and Pogrebnjak, Alexander

Subjects
STRUCTURAL stability, PREDICTION models, ALLOYS, FORECASTING
Abstract

High-Entropy Alloys (HEAs) represent a transformative class of materials characterized by multiple principal elements and high configurational entropy. This review article provides an in-depth examination of their structural particularities, prediction methodologies, and synthesis techniques. HEAs exhibit unique structural stability due to high-entropy effects, severe lattice distortions, and slow diffusion processes. Predictive models, including thermodynamic and kinetic approaches, are essential for understanding phase stability. Various synthesis methods impact HEA properties, and advanced characterization techniques are crucial for their study. The article highlights current applications and future research directions, emphasizing the potential of HEAs in diverse technological fields. [ABSTRACT FROM AUTHOR]

Published
2024
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28. Impact of Multilayer Architecture on the Tribological Behaviour of Wnx/Tisin Coating Versus Monolithic Wnx and Tisin Layers

Author

Smyrnova, Kateryna, primary, Sahul, Martin, additional, Bočáková, Barbora, additional, Haršáni, Marián, additional, Truchlý, Martin, additional, Sahul, Miroslav, additional, Vopát, Tomáš, additional, Pašák, Matej, additional, Maksakova, Olga, additional, Škrobáková, Ivana, additional, Čaplovič, Ľubomír, additional, and Pogrebnjak, Alexander, additional

Published
2024
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30. Microstructural, Electrical, and Tribomechanical Properties of Mo-W-C Nanocomposite Films.

Author

Smyrnova, Kateryna, Ivashchenko, Volodymyr I., Sahul, Martin, Čaplovič, Ľubomír, Skrynskyi, Petro, Kozak, Andrii, Konarski, Piotr, Koltunowicz, Tomasz N., Galaszkiewicz, Piotr, Bondariev, Vitalii, Zukowski, Pawel, Budzynski, Piotr, Borba-Pogrebnjak, Svitlana, Kamiński, Mariusz, Bónová, Lucia, Beresnev, Vyacheslav, and Pogrebnjak, Alexander

Subjects
NANOCOMPOSITE materials, MICROELECTROMECHANICAL systems, MAGNETRON sputtering, AMORPHOUS carbon, POWER electronics, TUNGSTEN alloys
Abstract

This study investigates the phase composition, microstructure, and their influence on the properties of Mo-W-C nanocomposite films deposited by dual-source magnetron sputtering. The synthesised films consist of metal carbide nanograins embedded in an amorphous carbon matrix. It has been found that nanograins are composed of the hexagonal β-(Mo2 + W2)C phase at a low carbon source power. An increase in the power results in the change in the structure of the carbide nanoparticles from a single-phase to a mixture of the β-(Mo2 + W2)C and NaCl-type α-(Mo + W)C(0.65≤k≤1) solid-solution phases. The analysis of electrical properties demonstrates that the nanograin structure of the films favours the occurrence of hopping conductivity. The double-phase structure leads to a twofold increase in the relaxation time compared to the single-phase one. Films with both types of nanograin structures exhibit tunnelling conductance without the need for thermal activation. The average distance between the potential wells produced by the carbide nanograins in nanocomposite films is approximately 3.4 ± 0.2 nm. A study of tribomechanical properties showed that Mo-W-C films composed of a mixture of the β-(Mo2 + W2)C and α-(Mo + W)C(0.65≤k≤1) phases have the highest hardness (19–22 GPa) and the lowest friction coefficient (0.15–0.24) and wear volume (0.00302–0.00381 mm2). Such a combination of electrical and tribomechanical properties demonstrates the suitability of Mo-W-C nanocomposite films for various micromechanical devices and power electronics. [ABSTRACT FROM AUTHOR]

Published
2024
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42. List of Contributors

Author

Ahmad, Sharif, primary, Ammar, Sh., additional, Bajpai, A.K., additional, Bhatt, Neha, additional, De Riccardis, M. Federica, additional, Dolez, Patricia I., additional, Eng, Kee Kok, additional, Ghasemi, Mostafa, additional, Ismail, Mokhtar Che, additional, Joshaghani, Ali Hassani, additional, Kakooei, Saeid, additional, Kar, Pradip, additional, Le, Xuan Tuan, additional, Li, Lawrence Kwok-Yan, additional, Lone, Mohammad Nadeem, additional, Mishra, Abhilasha, additional, Mohebbi, Hamed, additional, Nguyen, Thien Vuong, additional, Nguyen, Tuan Anh, additional, Nguyen Tri, Phuong, additional, Ouellet Plamondon, Claudiane M., additional, Pogrebnjak, Alexander D., additional, Ramesh, K., additional, Ramesh, S., additional, Rawat, Neha Kanwar, additional, Re, Marilena, additional, Rtimi, Sami, additional, Wani, Irshad A., additional, Wonnie Ma, I.A., additional, Zahidah, Khairina Azmi, additional, Zeb, Gul, additional, Zhou, Zhifeng, additional, and Zia, Abdul Wasy, additional

Published
2019
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45. Response Optimization of LiNbO3 Ultrasonic Transducers for High Temperature Measurement

Author

Zeng, Xiaomei, Pelenovich, Vasiliy O., Zhang, Xiangyu, Xu, Chang, Ding, Yue, Wang, Zheng, Chen, Zhiwen, Zhang, Jun, Yang, Bing, Pogrebnjak, Alexander, and Liu, Sheng

Abstract

LiNbO3 thin-film ultrasonic transducers were deposited using the RF magnetron sputtering technique. Optimization of the sample position in the deposition chamber and deposition parameters was carried out to obtain the strongest pulse-echo response of LiNbO3 transducers. The position of the sample in a plane parallel to the target surface had a significant impact on the transducer morphology, which changed from a columnar structure to a layer with embedded wedges. An exponential correlation between the amplitude of the pulse-echo response and the transducer thickness was found. The structural quality of the transducer layer was the main factor influencing the response amplitude. A temperature sensor in the form of a thin film ultrasonic transducer deposited on a bolt cup was prepared. To measure temperature, a linear dependence between longitudinal wave time-of-flight and bolt temperature was used. The optimization of the response of the transducer allows for more accurate temperature measurements using higher-order pulse echoes.

Published
2024
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46. Polycaprolactone–MXene Nanofibrous Scaffolds for Tissue Engineering

Author

Diedkova, Kateryna, primary, Pogrebnjak, Alexander D., additional, Kyrylenko, Sergiy, additional, Smyrnova, Kateryna, additional, Buranich, Vladimir V., additional, Horodek, Pawel, additional, Zukowski, Pawel, additional, Koltunowicz, Tomasz N., additional, Galaszkiewicz, Piotr, additional, Makashina, Kristina, additional, Bondariev, Vitaly, additional, Sahul, Martin, additional, Čaplovičová, Maria, additional, Husak, Yevheniia, additional, Simka, Wojciech, additional, Korniienko, Viktoriia, additional, Stolarczyk, Agnieszka, additional, Blacha-Grzechnik, Agata, additional, Balitskyi, Vitalii, additional, Zahorodna, Veronika, additional, Baginskiy, Ivan, additional, Riekstina, Una, additional, Gogotsi, Oleksiy, additional, Gogotsi, Yury, additional, and Pogorielov, Maksym, additional

Published
2023
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50. Effect of Bilayer Thickness and Bias Potential on the Structure and Properties of (TiZr/Nb)N Multilayer Coatings as a Result of Arc-PVD Deposition

Author

Rakhadilov Bauyrzhan, Pogrebnjak Alexander, Sagdoldina Zhuldyz, Buitkenov Dastan, Beresnev Vyacheslav, and Amina Mukhamedova

Subjects
multilayer coating, Arc-PVD, (TiZr/Nb)N, phase, wear resistance, hardness, General Materials Science
Abstract

This work is devoted to the study of the formation of nanostructured multilayer coatings (TiZr/Nb)N on the surface of an AISI 321 steel substrate depending on the deposition parameters of the Arc-PVD method. The results of the X-ray diffraction analysis showed the formation of solid solution (TiNb)N and ZrN in the multilayer coatings with an FCC structure, ε-NbN with a hexagonal structure, as well as with a small volume fraction of the ε-Ti2N and β-Nb2N phase. On the basis of phase composition data, it is possible to assume that an increase in the number of bilayers leads to a decrease in the nitrogen concentration in the bilayers and, consequently, to a decrease in the volume fraction of ε-NbN and β-Nb2N nitrides. In all investigated systems obtained at −100 V and −200 V bias potentials, ε-NbN is the main phase. The study of the element distribution over the thickness of the (TiZr/Nb)N coating confirms the results of the X-ray diffraction analysis. The use of the structure model in the form of alternating layers allows for significantly improving the adhesion characteristics of the protective coating, as well as ensuring their high hardness. Based on the experimental results, it is possible to analyze changes in the mechanical and tribological properties of multilayer coatings depending on the number of applied bilayers. The results of the study of the elastic modulus and hardness of multilayer coatings (TiZrNb)N with different numbers of bilayers showed that a large number of bilayers (small thickness of each individual layer) shows the lowest value of hardness. It is assumed that as the bilayer thickness decreases, the coating characteristics are closer to the monolayer alloy than to the multilayer structure.

Published
2022

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