TY - JOUR AU - Fogarassy, Zsolt AU - Wójcicka, Aleksandra AU - Cora, Ildikó AU - Rácz, Adél Sarolta AU - Grzanka, Szymon AU - Dodony, Erzsébet AU - Perlin, Piotr AU - Borysiewicz, Michał A. TI - Structural and electrical investigation of Al/Ti/TiN/Au based N-face n-GaN contact stack JF - MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING J2 - MAT SCI SEMICON PROC VL - 175 PY - 2024 PG - 12 SN - 1369-8001 DO - 10.1016/j.mssp.2024.108250 UR - https://m2.mtmt.hu/api/publication/34714097 ID - 34714097 AB - In this work, the structure of Ti/Al/TiN/Au contact layer stack on the N-face of a single-crystal n-GaN substrate is studied after heat treatment at 750 °C. Since TiN is widely regarded as a diffusion barrier in the stack, the formed structures with three different initial TiN thicknesses (15, 60 and 90 nm) in the contact layers are investigated in detail. The primary tool used for the structural investigations was a (scanning) transmission electron microscope ((S)TEM). In all three samples a low resistivity ohmic contact was formed. However, the TiN layer has not completely blocked the diffusion for any of the samples and both Al and Au diffused through the TiN layer at the temperature of 750 °C. As a result of the heat treatment, a complex AlN/TiN/Au2Al/TiN/Au + Al2.67O4 stack was formed on the surface of the GaN substrate. The measurements have not shown the often reported Ti–Al alloy phase in the samples. The formation of the AlN and TiN layers can be explained by the separation of N from GaN creating N vacancies in the GaN substrate which could help the formation of the ohmic behavior. LA - English DB - MTMT ER - TY - JOUR AU - Cadena Nogales, Ana Cristina AU - Pekker, Áron AU - Botka, Bea AU - Dodony, Erzsébet AU - Fogarassy, Zsolt AU - Pécz, Béla AU - Kamarás, Katalin TI - Encapsulation of the Graphene Nanoribbon Precursor 1, 2, 4‐trichlorobenzene in Boron Nitride Nanotubes at Room Temperature JF - PHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS J2 - PHYS STATUS SOLIDI-R VL - 17 PY - 2023 IS - 1 PG - 5 SN - 1862-6254 DO - 10.1002/pssr.202200284 UR - https://m2.mtmt.hu/api/publication/33138741 ID - 33138741 LA - English DB - MTMT ER - TY - CONF AU - Dodony, Erzsébet AU - Dódony, István AU - Sáfrán, György ED - Fried, Miklós TI - In-situ study of nickel silicide formation in thin films T2 - Symposium on Materials Science 2022 PB - Óbudai Egyetem C1 - Budapest SN - 9789634493204 PY - 2023 SP - 32 EP - 33 PG - 5 UR - https://m2.mtmt.hu/api/publication/33751712 ID - 33751712 LA - English DB - MTMT ER - TY - CONF AU - Dodony, Erzsébet AU - Dódony, István AU - Fogarassy, Zsolt AU - Pekker, Péter AU - Sáfrán, György ED - Steinbach, Gábor TI - DIFFRAKCIÓS INTENZITÁS MÉRÉSEK TEM-BEN II.: AZ EWALD KORREKCIÓ KITERJESZTÉSE. Diffracted intensity measurements in TEM II.: Extension of the Ewald correction TS - Diffracted intensity measurements in TEM II.: Extension of the Ewald correction T2 - A Magyar Mikroszkópos Társaság éves konferenciájának kivonatkönyve 2023 : Book of the Abstracts of the Annual Conference of HSM 2023 PY - 2023 SP - 28 EP - 31 PG - 4 UR - https://m2.mtmt.hu/api/publication/34487420 ID - 34487420 N1 - Előadás LA - English DB - MTMT ER - TY - CONF AU - Dodony, Erzsébet AU - Dódony, István AU - Fogarassy, Zsolt AU - Pekker, Péter AU - Sáfrán, György ED - Steinbach, Gábor TI - A γ -NIKKEL-SZILICID SZERKEZETI VÁLTOZATOSSÁGA. Structural variability of the γ-nickel-silicide TS - Structural variability of the γ-nickel-silicide T2 - A Magyar Mikroszkópos Társaság éves konferenciájának kivonatkönyve 2023 : Book of the Abstracts of the Annual Conference of HSM 2023 PY - 2023 SP - 26 EP - 28 PG - 3 UR - https://m2.mtmt.hu/api/publication/34487369 ID - 34487369 N1 - Előadás LA - English DB - MTMT ER - TY - JOUR AU - Maria Cristina, Silva Cisneros AU - Salmanzade, Khirdakhanim AU - Borbáth, Irina AU - Dodony, Erzsébet AU - Olasz, Dániel AU - Sáfrán, György AU - Kuncser, Andrei AU - Pásztiné Gere, Erzsébet AU - Tompos, András AU - Pászti, Zoltán TI - Reductive Treatment of Pt Supported on Ti0.8Sn0.2O2-C Composite: A Route for Modulating the Sn–Pt Interactions JF - NANOMATERIALS J2 - NANOMATERIALS-BASEL VL - 13 PY - 2023 IS - 15 PG - 23 SN - 2079-4991 DO - 10.3390/nano13152245 UR - https://m2.mtmt.hu/api/publication/34088284 ID - 34088284 AB - The composites of transition metal-doped titania and carbon have emerged as promising supports for Pt electrocatalysts in PEM fuel cells. In these multifunctional supports, the oxide component stabilizes the Pt particles, while the dopant provides a co-catalytic function. Among other elements, Sn is a valuable additive. Stong metal-support interaction (SMSI), i.e., the migration of a partially reduced oxide species from the support to the surface of Pt during reductive treatment is a general feature of TiO2-supported Pt catalysts. In order to explore the influence of SMSI on the stability and performance of Pt/Ti0.8Sn0.2O2-C catalysts, the structural and catalytic properties of the as prepared samples measured using XRD, TEM, XPS and electrochemical investigations were compared to those obtained from catalysts reduced in hydrogen at elevated temperatures. According to the observations, the uniform oxide coverage of the carbon backbone facilitated the formation of Pt–oxide–C triple junctions at a high density. The electrocatalytic behavior of the as prepared catalysts was determined by the atomic closeness of Sn to Pt, while even a low temperature reductive treatment resulted in Sn–Pt alloying. The segregation of tin oxide on the surface of the alloy particles, a characteristic material transport process in Sn–Pt alloys after oxygen exposure, contributed to a better stability of the reduced catalysts. LA - English DB - MTMT ER - TY - JOUR AU - Varga, Gábor AU - Szenti, Imre AU - Kiss, János AU - Baán, Kornélia AU - Halasi, Gyula AU - Óvári, László AU - Szamosvölgyi, Ákos AU - Mucsi, Róbert AU - Dodony, Erzsébet AU - Fogarassy, Zsolt AU - Pécz, Béla AU - Olivi, Luca AU - Sápi, András AU - Kukovecz, Ákos AU - Kónya, Zoltán TI - Decisive role of Cu/Co interfaces in copper cobaltite derivatives for high performance CO2 methanation catalyst JF - JOURNAL OF CO2 UTILIZATION J2 - J CO2 UTIL VL - 75 PY - 2023 PG - 13 SN - 2212-9820 DO - 10.1016/j.jcou.2023.102582 UR - https://m2.mtmt.hu/api/publication/34120023 ID - 34120023 AB - Thermo-catalytic bio-SNG (CH4) production is one of the useful tools for converting waste to gaseous fuels through CO2 conversion. To abundant properly, however, efficient, robust and cost-effective catalysts would be required. Bimetallic systems based on transition metals seem to be promising candidates for this task. The CoCu bimetallic system with in-situ generated interfaces was synthesized and used as a catalyst for CO2 methanation. The in-depth analysis of the structure-activity-selectivity relationships involving XRD, (NAP-)XPS, EXAFS and TEM-EDX revealed that the co-existence of Co0, CoO, and Cu0 in the proper distribution on the surface can ensure the selective production of methane. To fine-tune the surface composition of the bimetallic systems, a systematic alteration of the Cu:Co ratio in the precursor spinel structures must be performed. Cu0.4Co2.6O4 derivative, stabilizing subsurface Cu(I)–O specimen, showed the best performance with high activity (12,800 nmol g–1 s–1) and a remarkable selectivity of 65–85% for methane in a wide temperature range (250–425 °C). In studying the mechanistic aspects of methanation, it has been shown that the hydrogenation of active carbon at the surface or below the surface is the key step for the production of methane. So far, this cobalt-catalyzed sub-step has been proposed in catalytic Fischer-Tropsch syntheses. LA - English DB - MTMT ER - TY - JOUR AU - Dodony, Erzsébet AU - Rečnik, Aleksander AU - Dódony, István AU - Sáfrán, György TI - In situ TEM study of Ni-silicides formation up to 973K JF - JOURNAL OF ALLOYS AND COMPOUNDS J2 - J ALLOY COMPD VL - 918 PY - 2022 PG - 8 SN - 0925-8388 DO - 10.1016/j.jallcom.2022.165466 UR - https://m2.mtmt.hu/api/publication/32865859 ID - 32865859 AB - Low-temperature solid-state reactions between Ni and Si were studied using in situ transmission electron microscopy (TEM). In the experiments thin amorphous silicon (a-Si) films were laid on Ni micro-grids and heated up to 973 K. In our approach the supporting Ni-grid serves as an unlimited source of nickel to successively form the whole range of Ni-silicide phases while diffusing into amorphous silicon. Unlike other thin film experiments where Ni and Si are layered on top of each other, our arrangement enables lateral diffusion of Ni along the Si layer and therefore enables the formation and study of successive Ni-Si phases side by side. That allowed us to observe in situ α-NiSi2 as the first reaction product, in contrast to most studies that had reported either δ-Ni2Si or θ-Ni2Si as the first phase to form. α-NiSi2 was continuously present at the reaction front propagating into the a-Si film. The phase sequence followed the increasing Ni concentration from a-Si towards the Ni-grid: α-NiSi2, NiSi, Ni3Si2, δ-Ni2Si, γ-Ni31Si12 and Ni3Si. Almost all known Ni-silicide phases were found to form at relatively low temperatures except the θ-Ni2Si, β-NiSi2 and β3-Ni3Si. The dominant phase was γ-Ni31Si12 which appeared in three structural modifications, differing in lattice periodicity along the c-axis. The periodicity of the basic γ-Ni31Si12 structure along the c-axis is ~12 Å (c0 = 12.288 Å) and that of the other two modifications were ~18 Å and ~36 Å, denoted by S12, S18 and S36 respectively. Of the three, only S12 has a structural model, S18 had been previously observed by Chen, but S36 had not been documented in previous works. During our in situ heating experiments, in addition to the Ni-silicide layer formation a new phenomenon was observed, namely the appearance, growth and transformation of Ni-silicide whiskers which was attributed to the accumulation of compressive stress in the thin layer. LA - English DB - MTMT ER - TY - CHAP AU - Dodony, Erzsébet AU - Dódony, István AU - Sáfrán, György ED - Kittel, Ágnes ED - Solymosi, Katalin ED - Barna, László TI - In situ TEM vizsgálatok nikkel-szilicid vékonyréteg rendszerben. In situ TEM results in the nikkel-silicon thin film system TS - In situ TEM results in the nikkel-silicon thin film system T2 - A Magyar Mikroszkópos Társaság 2022 Konferenciájának Kivonatkönyve PB - Magyar Mikroszkópos Társaság CY - Budapest SN - 9786158210706 PY - 2022 SP - 19 EP - 21 PG - 2 UR - https://m2.mtmt.hu/api/publication/33342019 ID - 33342019 LA - English DB - MTMT ER - TY - JOUR AU - Szamosvölgyi, Ákos AU - Rajkumar, T. AU - Sápi, András AU - Szenti, Imre AU - Ábel, Marietta AU - Gomez Perez, Juan Fernando AU - Baán, Kornélia AU - Fogarassy, Zsolt AU - Dodony, Erzsébet AU - Pécz, Béla AU - Garg, Seema AU - Kiss, János AU - Kukovecz, Ákos AU - Kónya, Zoltán TI - Interfacial Ni active sites strike solid solutional counterpart in CO2 hydrogenation JF - ENVIRONMENTAL TECHNOLOGY & INNOVATION J2 - ENVIRON TECH INNOV VL - 27 PY - 2022 PG - 12 SN - 2352-1864 DO - 10.1016/j.eti.2022.102747 UR - https://m2.mtmt.hu/api/publication/32891371 ID - 32891371 LA - English DB - MTMT ER -