TY - JOUR AU - Lábár, János AU - Pécz, Béla TI - Transzmissziós elektronmikroszkópia az MFA-ban JF - FIZIKAI SZEMLE J2 - FIZIKAI SZEMLE VL - 74 PY - 2024 IS - 3 SP - 84 EP - 87 PG - 4 SN - 0015-3257 UR - https://m2.mtmt.hu/api/publication/34727542 ID - 34727542 LA - Hungarian DB - MTMT ER - TY - JOUR AU - Dumas, P. AU - Opprecht, M. AU - Kerdilès, S. AU - Lábár, János AU - Pécz, Béla AU - Lefloch, F. AU - Nemouchi, F. TI - Superconductivity in laser-annealed monocrystalline silicon films: The role of boron implant JF - APPLIED PHYSICS LETTERS J2 - APPL PHYS LETT VL - 123 PY - 2023 IS - 13 PG - 10 SN - 0003-6951 DO - 10.1063/5.0166870 UR - https://m2.mtmt.hu/api/publication/34332659 ID - 34332659 LA - English DB - MTMT ER - TY - CONF AU - Lábár, János AU - Pécz, Béla AU - Sulyok, Attila AU - Chiod, F ED - Steinbach, Gábor TI - SZUPRAVEZETŐ SZILÍCIUM. Superconducting Silicon TS - Superconducting Silicon T2 - A Magyar Mikroszkópos Társaság éves konferenciájának kivonatkönyve 2023 : Book of the Abstracts of the Annual Conference of HSM 2023 PY - 2023 SP - 54 EP - 56 PG - 3 UR - https://m2.mtmt.hu/api/publication/34487551 ID - 34487551 N1 - Előadás LA - English DB - MTMT ER - TY - JOUR AU - Lábár, János AU - Hajagos-Nagy, Klára AU - Das, Partha P. AU - Gomez-Perez, Alejandro AU - Radnóczi, György TI - Simple ePDF: A Pair Distribution Function Method Based on Electron Diffraction Patterns to Reveal the Local Structure of Amorphous and Nanocrystalline Materials JF - NANOMATERIALS J2 - NANOMATERIALS-BASEL VL - 13 PY - 2023 IS - 24 PG - 17 SN - 2079-4991 DO - 10.3390/nano13243136 UR - https://m2.mtmt.hu/api/publication/34435393 ID - 34435393 AB - Amorphous, glassy or disordered materials play important roles in developing structural materials from metals or ceramics, devices from semiconductors or medicines from organic compounds. Their local structure is frequently similar to crystalline ones. A computer program is presented here that runs under the Windows operating system on a PC to extract pair distribution function (PDF) from electron diffraction in a transmission electron microscope (TEM). A polynomial correction reduces small systematic deviations from the expected average Q-dependence of scattering. Neighbor distance and coordination number measurements are supplemented by either measurement or enforcement of number density. Quantification of similarity is supported by calculation of Pearson’s correlation coefficient and fingerprinting. A rough estimate of fractions in a mixture is computed by multiple least-square fitting using the PDFs from components of the mixture. PDF is also simulated from crystalline structural models (in addition to measured ones) to be used in libraries for fingerprinting or fraction estimation. Crystalline structure models for simulations are obtained from CIF files or str files of ProcessDiffraction. Data from inorganic samples exemplify usage. In contrast to previous free ePDF programs, our stand-alone program does not need a special software environment, which is a novelty. The program is available from the author upon request. LA - English DB - MTMT ER - TY - JOUR AU - Lábár, János AU - Pécz, Béla AU - van, Waveren Aiken AU - Hallais, Géraldine AU - Desvignes, Léonard AU - Chiodi, Francesca TI - Strain Measurement in Single Crystals by 4D-ED JF - NANOMATERIALS J2 - NANOMATERIALS-BASEL VL - 13 PY - 2023 IS - 6 PG - 12 SN - 2079-4991 DO - 10.3390/nano13061007 UR - https://m2.mtmt.hu/api/publication/33698442 ID - 33698442 AB - A new method is presented to measure strain over a large area of a single crystal. The 4D-ED data are collected by recording a 2D diffraction pattern at each position in the 2D area of the TEM lamella scanned by the electron beam of STEM. Data processing is completed with a new computer program (available free of charge) that runs under the Windows operating system. Previously published similar methods are either commercial or need special hardware (electron holography) or are based on HRTEM, which involves limitations with respect to the size of the field of view. All these limitations are overcome by our approach. The presence of defects results in small local changes in orientation that change the subset of experimentally available diffraction spots in the individual patterns. Our method is based on a new principle, namely fitting a lattice to (a subset of) measured diffraction spots to improve the precision of the measurement. Although a spot to be measured may be missing in some of the patterns even the missing spot can be precisely measured by the lattice determined from the available spots. Application is exemplified by heavily boron-doped silicon with intended usage as a low-temperature superconductor in qubits. LA - English DB - MTMT ER - TY - JOUR AU - Lipcsei, Sándor AU - Kalácska, Szilvia AU - Ispánovity, Péter Dusán AU - Lábár, János AU - Dankházi, Zoltán AU - Groma, István TI - Statistical properties of fractal type dislocation cell structures JF - PHYSICAL REVIEW MATERIALS J2 - PHYS REV MAT VL - 7 PY - 2023 IS - 3 PG - 11 SN - 2475-9953 DO - 10.1103/PhysRevMaterials.7.033604 UR - https://m2.mtmt.hu/api/publication/33731168 ID - 33731168 LA - English DB - MTMT ER - TY - JOUR AU - Glowka, Karsten AU - Zubko, Maciej AU - Świec, Paweł AU - Prusik, Krystian AU - Szklarska, Magdalena AU - Chrobak, Dariusz AU - Lábár, János AU - Stróż, Danuta TI - Influence of Molybdenum on the Microstructure, Mechanical Properties and Corrosion Resistance of Ti20Ta20Nb20(ZrHf)20−xMox (Where: x = 0, 5, 10, 15, 20) High Entropy Alloys JF - MATERIALS J2 - MATERIALS VL - 15 PY - 2022 IS - 1 PG - 21 SN - 1996-1944 DO - 10.3390/ma15010393 UR - https://m2.mtmt.hu/api/publication/32582299 ID - 32582299 AB - The presented work was focused on investigating the influence of the (hafnium and zirconium)/molybdenum ratio on the microstructure and properties of Ti20Ta20Nb20(ZrHf)20−xMox (where: x = 0, 5, 10, 15, 20 at.%) high entropy alloys in an as-cast state. The designed chemical composition was chosen due to possible future biomedical applications. Materials were obtained from elemental powders by vacuum arc melting technique. Phase analysis revealed the presence of dual body-centered cubic phases. X-ray diffraction showed the decrease of lattice parameters of both phases with increasing molybdenum concentration up to 10% of molybdenum and further increase of lattice parameters. The presence of two-phase matrix microstructure and hafnium and zirconium precipitates was proved by scanning and transmission electron microscopy observation. Mechanical property measurements revealed decreased micro- and nanohardness and reduced Young’s modulus up to 10% of Mo content, and further increased up to 20% of molybdenum addition. Additionally, corrosion resistance measurements in Ringers’ solution confirmed the high biomedical ability of studied alloys due to the presence of stable oxide layers. LA - English DB - MTMT ER - TY - JOUR AU - Hung, Pham Tran AU - Kawasaki, Megumi AU - Szabo, Abel AU - Lábár, János AU - Hegedus, Zoltan AU - Gubicza, Jenő TI - Influence of Degree of Severe Plastic Deformation on Thermal Stability of an HfNbTiZr Multi-Principal Element Alloy Processed by High-Pressure Torsion JF - NANOMATERIALS J2 - NANOMATERIALS-BASEL VL - 12 PY - 2022 IS - 19 PG - 22 SN - 2079-4991 DO - 10.3390/nano12193371 UR - https://m2.mtmt.hu/api/publication/33187153 ID - 33187153 N1 - Department of Materials Physics, Eötvös Loránd University, P.O.B. 32, Budapest, 1518, Hungary School of Mechanical, Industrial and Manufacturing Engineering, Oregon State University, Corvallis, OR 97331, United States Institute for Technical Physics and Materials Science, Centre for Energy Research, Budapest, 1121, Hungary Deutsche Elektronen-Synchrotron DESY, Hamburg, 22607, Germany Cited By :1 Export Date: 23 April 2024 Correspondence Address: Gubicza, J.; Department of Materials Physics, P.O.B. 32, Hungary; email: jeno.gubicza@ttk.elte.hu AB - Severe plastic deformation (SPD) is an effective route for the nanocrystallization of multi-principal element alloys (MPEAs). The stability of the refined microstructure is important, considering the high temperature applications of these materials. In the present study, the effect of SPD on the stability of a body-centered cubic (bcc) HfNbTiZr MPEA was investigated. SPD was performed using a high-pressure torsion (HPT) technique by varying the number of turns between 1/2 and 10. The evolution of phase composition and microstructure was studied near the disk centers and edges where the imposed strain values were the lowest and highest, respectively. Thus, the shear strain caused by HPT varies between 3 (1/2 turn, near the center) and 340 (10 turns, near the edge). It was found that during annealing up to 1000 K, the bcc HfNbTiZr alloy decomposed into two bcc phases with different lattice constants at 740 K. In addition, at high strains a hexagonal close packed (hcp) phase was formed above 890 K. An inhomogeneous elemental distribution was developed at temperatures higher than 890 K due to the phase decomposition. The scale of the chemical heterogeneities decreased from about 10 mu m to 30 nm where the shear strain increased from 3 to 340, which is similar to the magnitude of grain refinement. Anneal-induced hardening was observed in the MPEA after HPT for both low and high strains at 740 K, i.e., the hardness of the HPT-processed samples increased due to heat treatment. At low strain, the hardness remained practically unchanged between 740 and 1000 K, while for the alloy receiving high strains there was a softening in this temperature range. LA - English DB - MTMT ER - TY - JOUR AU - Hung, Pham Tran AU - Kawasaki, Megumi AU - Han, Jae-Kyung AU - Szabó, Ábel AU - Lábár, János AU - Hegedűs, Zoltán AU - Gubicza, Jenő TI - Thermal stability of nanocrystalline CoCrFeNi multi-principal element alloy: Effect of the degree of severe plastic deformation JF - INTERMETALLICS J2 - INTERMETALLICS VL - 142 PY - 2022 PG - 11 SN - 0966-9795 DO - 10.1016/j.intermet.2021.107445 UR - https://m2.mtmt.hu/api/publication/32549660 ID - 32549660 N1 - Department of Materials Physics, Eötvös Loránd University, P.O.B. 32, Budapest, H-1518, Hungary School of Mechanical, Industrial and Manufacturing Engineering, Oregon State University, Corvallis, OR 97331, United States Institute for Technical Physics and Materials Science, Centre for Energy Research, Budapest, Hungary Deutsche Elektronen-Synchrotron DESY, Hamburg, 22607, Germany Cited By :4 Export Date: 23 April 2024 CODEN: IERME Correspondence Address: Gubicza, J.; Department of Materials Physics, P.O.B. 32, Hungary; email: jeno.gubicza@ttk.elte.hu AB - The effect of the degree of severe plastic deformation (SPD) on the thermal stability of a nanocrystalline CoCrFeNi multi-principal element alloy was studied. The SPD method of high-pressure torsion (HPT) was utilized to achieve the nanocrystalline microstructure. The structural stability was investigated near the centers and edges of the HPT-processed disks deformed for ½, 1, 5 and 10 turns. For almost all studied samples, two exothermic peaks in the temperature ranges of 600–750 and 750–950 K were observed by differential scanning calorimetry (DSC) between room temperature and 1000 K. The saturation released heat value for the first DSC peak was about 4 J/g that was achieved at the shear strain of ∼200. For the second exothermic peak, the released heat saturated at the shear strain of about 20 with the value of about 6–7 J/g. It was revealed that the first DSC peak is related to the annihilation of dislocations for low degree of deformation. At the same time, for edge parts of the disks processed by one or higher numbers of turns the vacancy annihilation has also a major contribution to the first exothermic peak. The annihilated vacancy concentration estimated from the released heat was between (0.6–0.9) × 10−3. The second DSC peak was related to the disappearance of grain boundaries due to recrystallization and annihilation of the remaining dislocations. The HPT-processed CoCrFeNi MPEA samples exhibited very high hardness values between 4000 and 5100 MPa, depending on the number of turns and the location along the disk radius. The hardness decreased only during the second exothermic peak when recrystallization occurred. LA - English DB - MTMT ER - TY - CHAP AU - Lábár, János AU - Pécz, Béla AU - Francesca, Chiodi AU - Fabrice, Nemouchi AU - Zhen, Zhang AU - Shi-Li, Zhang AU - François, Lefloch ED - Kittel, Ágnes ED - Solymosi, Katalin ED - Barna, László TI - A TEM szerepe a Qubitek fejlesztésében. Role of TEM in the development of Qubits TS - Role of TEM in the development of Qubits T2 - A Magyar Mikroszkópos Társaság 2022 Konferenciájának Kivonatkönyve PB - Magyar Mikroszkópos Társaság CY - Budapest SN - 9786158210706 PY - 2022 SP - 146 EP - 149 PG - 4 UR - https://m2.mtmt.hu/api/publication/33342457 ID - 33342457 LA - English DB - MTMT ER -