Zoltan Erdelyi

• PhD, Habil., Doctor of the Academy (Hungarian Academy of Sciences, Hungary)
• Head of Department at University of Debrecen

Si is a promising anode material for Li-ion batteries due to its high specific capacity compared to conventional graphite and metal oxides; however, the pulverization during the lithiation/de-lithiation reduces the Coulombic efficiency and cycle stability. Si nanostructures with an increased surface-to-volume ratio, such as porous Si (PS) and Si na...

We demonstrate the band gap programming of inverse opals by fabrication of different wall thickness by atomic layer deposition (ALD). The opal templates were synthesized using polystyrene and carbon nanospheres by the vertical deposition method. The structure and properties of the TiO2 inverse opal samples were investigated using Scanning Electron...

Nickel oxide (NiO) is one of the most popular hydrogenation catalysts. In heterogeneous catalysis, nickel oxide is used, for example, as a suitable methanation catalyst in the Fischer–Tropsch reaction not only for CO hydrogenation but also in the modified Fischer–Tropsch reaction with CO2. However, CH4 selectivity and CO2 conversion strongly depend...

Zinc oxide inverse opal (IO) has excellent photocatalytic properties, while Al 2 O 3 has high chemical stability and negligible photocatalytic activity. However, combining these materials creates a crystalline ZnO-amorphous Al 2 O 3 composite IO photonic crystal material with improved photocatalytic performance. In this study, ZnO IO and ZnO-Al 2 O...

The copper element (Cu) substituted ZnO with the common formula ZnO70/Cux/ZnO70 (x = 20, 50, and 70 nm) was manufactured using ALD and Dc magnetron sputtering techniques, as a function of the concentration of Cu as interlayer. The effect of the amount of Cu doped in ZnO on the character and dielectric and impedance properties was evaluated. Scannin...

We report on the construction and investigation of Li–air batteries consisting of a charcoal cathode and cotton texture soaked with different organic solvents containing a lithium triflate (LiOTf) electrolyte. Charcoal was found to be an appropriate cathode for Li–air batteries. Furthermore, cycling tests showed stable operation at over 800 cycles...

Titania was mixed with different percentages of alumina during the preparation of an 8 nm film by atomic layer deposition. The effect of mixing on the transmittance and absorption spectra was investigated. Increasing the alumina percentage increased the transmittance and decreased the absorption of light. The films showed an indirect allowed transi...

In the present work, a series of metal nanoparticle-decorated carbogels (M-DCs) was synthesized starting from beads of parent metal-crosslinked alginate aerogels (M-CAs). M-CAs contained Ca(ii), Ni(ii), Cu(ii), Pd(ii) and Pt(iv) ions and were converted to M-DCs by pyrolysis under a N2 atmosphere up to pyrolysis temperatures of TP = 600 °C. The text...

In this study, we focus on the influence of the deposition process of ZnO thin films with a thickness of 250 nm—grown on glass and silicon substrates by atomic layer deposition (ALD) technique—on morphology, optical properties, AC conductivity, and dielectric properties. The atomic structure of the ZnO film was analyzed using scanning electron micr...

3D metal nanostructures are often the basis of several applications such as in catalysis, plasmonics, medical diagnosis, therapy, drug screening, ophthalmologic, and biomedical applications. Porous gold nanoparticles (PGNs) are intensively investigated due to their outstanding morphological as well as advantageous optical properties. Unfortunately,...

In comparison to conventional nano-infiltration approaches, the atomic layer deposition (ALD) technology exhibits greater potential in the fabrication of inverse opals (IOs) for photocatalysts. In this study, TiO 2 IO and ultra-thin films of Al 2 O 3 on IO were successfully deposited using thermal or plasma-assisted ALD and vertical layer depositio...

Substantial consideration is being devoted to the innovation of AC Conductivity, sheet resistance measurements and Microhardness as a function of Cu interlayer thickness of conductive ZnO/Cu/ZnO thin films. ZnO layer was successfully prepared via atomic layer deposition (ALD), while Cu interlayer was deposited by Dc magnetron sputtering. The combin...

The a.c. conduction and the dielectric response were performed on bi-layers and quadri-layers of transparent Titania and Zinc white (i.e., TiO2/ZnO) thin film oxides of 100 nm thickness, deposited using an atomic layer deposition (ALD) system at 200 °C on silicon (100) substrates. The results show that Jonscher’s power law obeys a.c. conductivity (...

Thin films of ZnO with different thicknesses (ranging from 8 to 40 nm) have been prepared by plasma-enhanced atomic layer deposition. Grazing incidence X-ray diffraction shows the nano-crystalline structure of the films with high degree of disorder. The films have also lattice oxygen and non-lattice oxygen where the film with 20 nm thickness has th...

In this study we investigated the material properties of ZnO thin film of ≈ 300 nm thickness, grown on glass and silicon substrates by using atomic layer deposition (ALD) technique. Structural characterization was carried out using incident X-ray diffraction pattern. The microstructural evolution was accompanied by the grain size measurement. A key...

In this article, the performance of brass electrode was investigated in a Zn-air (charcoal-based cathode) rechargeable battery. The construction of the battery was carried out with biodegradable materials, namely a cotton cloth diaphragm and carboxymethyl cellulose sodium salt (CMC-Na) viscosity modifier, while the battery skeleton was printed by 3...

In this research, we report a comparative study of trilayer TiO2(60 nm)/Cu/TiO2(60 nm) thin film as a function of different Cu interlayer thickness (20, 40 and 60 nm), fabricated by atomic layer deposition (ALD) and DC magnetron sputtering. The surface morphology, elemental information and optical properties, were tested as a function of Cu interla...

The effect of pre-irradiation on a stack of metal multilayer thin films (MLTF) with low-energy Ar⁺ ions followed by thermal annealing of the stack has been studied. A three-layer Ni/Cu/V structure represented the as-fabricated MLTF samples. Each layer had a thickness of 25 nm. The entire assembly was built on Si using magnetron sputtering with diff...

Applying scanning electron microscopy in transmission mode and grazing incidence X-ray diffraction, we investigated the spinel-forming solid-state reaction between crystalline ZnO and amorphous Al2O3 layers prepared by atomic layer deposition. We observed two-stage phase growth of the crystalline ZnAl2O4 product layer. During the first stage, flat,...

In the current research, surface-modified SiO2 nanoparticles were used upon immersion in an applied base fluid (ethylene glycol:water = 1:1). The atomic layer deposition method (ALD) was introduced to obtain a thin layer of TiO2 to cover the surface of SiO2 particles. After the ALD modification, the TiO2 content was monitored by energy dispersive X...

In this paper, we focused our attention on the tailoring of structure and optical analysis as a function of Cu interlayer between the ZnO layers. The Cu interlayer was deposited by magnetron sputtering, while the ZnO layers were deposited by atomic layer deposition. Morphological analysis, based on grazing incident X-ray diffraction patterns and sc...

Coupling TiO2 nanofibers with other semiconductor metal oxides can effectively extend the light absorbability of TiO2 to the visible range of the electromagnetic spectrum. This study demonstrates the synthesis of TiO2–MoO3 composite nanofibers via electrospinning using Ti and Mo water-soluble precursors. Aqueous solutions of these precursors were a...

In this paper, we present a study on thermal conductivity and viscosity of nanofluids containing novel atomic layer deposition surface-modified carbon nanosphere (ALD-CNS) and carbon nanopowder (ALD-CNP) core-shell nanocomposites. The nanocomposites were produced by atomic layer deposition of amorphous TiO2. The nanostructures were characterised by...

In this paper, the effect of frequency and temperature on AC conductivity and dielectric parameters of multilayered TiO2/ZnO thin films have been reported. Among other techniques, the multy layer deposition (ALD) seems to be a promice approach. The fabricated multilayer thin films were grown on Si (100) substrate at 373 K and were nominally 100nm t...

In this paper an environmentally friendly high performance prototype of rechargeable Zn-air battery using cellulose based biodegradable matters as additive and diaphragm is reported. During designing we were aspired to construct a heavy metal free cell containing nontoxic, commercially available biodegradable feedstock. The fix cell geometry was gr...

In the present work, the effect of interference of highly transparent and conducting TiO2/Cu/TiO2 nanolaminated films with various Cu metallic interlayer thickness grown on Si (100) substrates by atomic layer deposition (ALD) and magnetron sputtering techniques on the dielectric properties and the AC conductivity of the as-prepared thin films, in t...

In this paper, we combine the atomic layer deposition synthesis method of inverse opal with the hydrothermal growth of nanorods. From 460 nm polystyrene nanospheres opal crystals were produced using vertical deposition on Si wafers. The opal templates were covered with ZnO by atomic layer deposition. High temperature annealing was used to remove th...

Graphene films were grown by chemical vapor deposition on Cu foil. The obtained samples were characterized by Raman spectroscopy, ellipsometry, X-ray photoelectron spectroscopy and electron back-scatter diffraction. We discuss the time-dependent changes in the samples, estimate the thickness of emerging Cu2O beneath the graphene and check the orien...

With this work we attempt to raise awareness of spinodal decomposition among the members of the ion implantation researcher community. In the literature about nanoparticle formation via ion implantation, spinodal decomposition is rarely mentioned. Probably because it is not associated with individual particles which are often the desired goal of th...

Penetration paths caused by nanoscopic defects in plasma-enhanced atomic layer deposited (PEALD) Al2O3 thin films could increase their transmission rate, mechanical limitations could impair their encapsulation utility. In contrast, this phenomenon could be beneficial in the case of polymer electrolyte fuel cells containing a proton exchange membran...

In this work core/shell composite polymer/TiO2 nanofibers and from those TiO2 nanotubes were prepared. First, poly(vinyl alcohol) (PVA) and poly(vinylpyrrolidone) (PVP) fibers were synthetized by electrospinning. They were covered with a 100 nm thick amorphous TiO2 layer by atomic layer deposition at 50 °C. Later the polymer core was removed by two...

In this research we report a comparative study of multilayers of TiO2/ZnO thin films, grown on glass and silicon substrates by atomic layer deposition (ALD) at 100 °C. All prepared multilayers are nominally 100 nm thick with a varying number of alternating TiO2/ZnO layers. The obtained data from X-ray diffraction pattern suggest that layer growth d...

Interface induced diffusion had been identified in a thin film system damaged by electron bombardment. This new phenomenon was observed in Al 2 O 3 (some nm thick)/Si substrate system, which was subjected to low energy (5 keV) electron bombardment producing defects in the Al 2 O 3 layer. The defects produced partially relaxed. The rate of relaxatio...

Determining binary phase diagrams for nanoparticles proves to be a very difficult task regardless if it is tried either by computer simulations, theoretical considerations or experiments. In this work, using 3D Object Stochastic Kinetic Modelling Framework (3DO-SKMF) computer simulations, we reveal some of the reasons why this is the case. First of...

In this article, we report the development of a novel Zn-air rechargeable battery with charcoal/graphite cathode and dicarboxyl telehelic polyethylene glycol (PEG) additives with different molecular weights (Mn: 600 Da, 1500 Da, 3300 Da). The battery is free of heavy metals and all of the used materials are easily available and non-toxic. The dicar...

Extending the absorption range of TiO2 nanofibers to visible light is a great improvement of the photocatalytic property of TiO2. In this study, TiO2/WO3/C/N nanofibers were prepared by electrospinning using precursors soluble in water then annealing in argon. Titanium(IV) bis(ammonium lactato)dihydroxide (TiBALDH) and ammonium metatungstate (AMT)...

Samples of ZnO/TiO2 bilayer films with various layer thickness were fabricated by atomic layer deposition (ALD). The X-ray diffraction (XRD) patterns revealed the absence of sharp peaks and confirms the amorphous nature of the samples under study. The absorption spectra of ZnO/TiO2 for the three samples were obtained in view of incident wavelength...

Interface induced diffusion had been identified in thin film system damaged by electron bombardment. This new phenomenon was observed in Al 2 O 3 (some nm thick) / Si substrate system, which was subjected to low energy (5 keV) electron bombardment producing defects in the Al 2 O 3 layer. The defects produced partially relaxed. The rate of relaxatio...

In this work, we report the development of a measurement chamber linked with a quadrupole mass spectrometer (QMS) for in situ investigation of the effect of thin film cracking on the gas permeation of coated flexible polymeric substrates. The chamber enables the establishment of a bulged state of the substrate/coating system, which causes the crack...

Atomic layer deposition (ALD) on polymer substrates often requires a modification of the polymer surface properties. Plasma-enhanced ALD (PE-ALD) process is capable of establishing improved coating/substrate adhesion and layer properties by a plasma pre-treatment prior to the layer deposition. Low density polyethylene (LDPE) films were plasma treat...

We present an effective computer simulation method, called 3D object stochastic kinetic modelling framework (3DO-SKMF), to calculate atomic movements in 3D objects including surface segregation and Gibbs–Thomson effect (surface curvature). Objects with any kind of shapes can easily be considered thanks to the flexibility and versatility of the mode...

In this work, we evaluate the water vapor transmission rate (WVTR), the permeability (P), solubility (S), and diffusion (D) coefficients of Paraloid B44, Paraloid B72, and Incralac coatings in the temperature range of 5–35°C. The Arrhenius function—diffusion activation energy and preexponential factor—has also been determined from the data: DB44=35...

Porous gold nanoparticles (PGNs) are very popular due to their high surface/volume ratio, moreover they have stronger plasmonic properties than their solid counterparts. These properties make the porous gold nanoparticles very useful for lots of applications, for instance chemical sensors, cancer therapy applications. For applications, however, it...

Porous nanoparticles are very popular because of their high surface/volume ratio; moreover, they have stronger plasmonic properties than their solid counterparts. Due to these properties, these are potential candidates in optical, or even in ophthalmological applications. We prepared porous gold nanoparticles on SiO 2 / Si as well as on sapphire su...

Thin film properties are extremely sensitive to the film preparation conditions, thus our research is dedicated to establish the correlation between the deposition parameters and properties in Al2O3/ZnO bilayered and Al2O3/Al2O3-ZnO mixed oxide/ZnO trilayred thin film samples prepared by atomic layer deposition (ALD) technique with the same total t...

Porous gold nanoparticles (PGNs) are usually prepared in an immobilized form on a solid substrate, which is not practical in many applications. In this work, a simple method is reported for the preparation and stabilization of mesoporous gold particles of a few hundred nanometers in size in aqueous suspension. Nanoparticles of Ag-Au alloy were fabr...

Nitrogen doped carbon aerogel was used as a substrate for the atomic layer deposition of TiO2 and ZnO layers in various thicknesses. The bare and composite products were analyzed using...

The influence of the 25-nm-thick Cr and V barrier layer on the diffusion and chemical composition formation in Ni/Cu bilayer films under annealing conditions was studied. Cu-Ni solid solution formation onset was found in both cases after annealing at 450 C, which led to constantan Cu53Ni47 alloy formation at 550 C. Cr intense diffusion towards the...

This research presents strong photocatalytic activity for amorphous TiO1.7 prepared by atomic layer deposition to decompose the LBR (Levafix Brilliant Red) dye. LBR is an example of the pollutant dyes in the textile industrial wastewater. This activity has been enhanced significantly through decreasing the thickness from 40 to 8 nm. This behavior i...

In this article, the capability of encoding information using a homologous series of monodisperse monomethoxypolyethylene glycols (mPEG), with a number of ethylene oxide units ranging from nEO = 5 to 8, and monodisperse linear aliphatic isocyanates containing a number of CH2 units from 3 to 7, is demonstrated. The “click” reaction of the two corres...

Highly transparent zinc oxide thin films with varied layer thicknesses have been prepared on microscopic glass substrates at 200 °C. Films thickness was measured by stylus profilometer. The films have been investigated for their structure using X-Ray diffraction; the patterns showed their amorphous nature. The dispersion parameters i.e. refractive...

We report results for spinodal decomposition in Ag-Cu binary system. The asymmetric miscibility gap of any binary system necessarily means that the gradient energy coefficient κ is composition dependent. We demonstrate that while this composition dependence of κ does not modify the solubility curve and even the equilibrium interface profile hardly...

Although Al2O3 is considered photocatalytically inactive, in this research, novel Al-rich Al2O3 ultra-thin films are employed for the first time as fast and active photocatalysts for water treatment from organic dyes. These films are prepared using plasma enhanced atomic layer deposition (ALD). Structure of the films is investigated using X-ray dif...

Abstract. Ni(25 nm)/Cu(25 nm)/Cr(25 nm) thin films were deposited by DC magnetron sputtering at room temperature onto Si(100) single-crystal substrates and irradiated by low-energy Ar+ ions in the energy range of 400 - 2000 eV with fluences of 1.4x1016 - 1.1x1017 ion/cm2. Influence of the ion bombardment on the structural properties, surface morpho...

Carbon nanospheres were used as templates for the first time to prepare titania inverse opal photonic crystal. From the spheres, opal colloid crystals were made by vertical deposition on microscope slides, and TiO2 was grown on them using atomic layer deposition (ALD). For this technique, the relatively high thermal stability and the presence of ox...

We report a quantitative multiscale (MS) procedure based on the recently developed Stochastic Kinetic Mean Field approach (SKMF) [Erdélyi, M. Pasichnyy, V. Bezpalchuk, J. J. Tomán, B. Gajdics, and A. M. Gusak, Comput. Phys. Commun. 204, 31–37 (2016)], combined with the Phase Field model (PFM) and CALPHAD database, to study the nucleation-growth-coa...

Proper understanding of structural and compositional stability of metastable alloys synthesized in binary systems with positive heat of mixing must be based on the knowledge of the diffusion process. The study of diffusion in immiscible systems includes difficulties because the components do not mix with each other but rather separate. For this rea...

Vertically aligned carbon nanotubes (VACNTs or “CNT forest”) were decorated with semiconductor particles (TiO2 and ZnO) by atomic layer deposition (ALD). Both the structure and morphology of the components were systematically studied using scanning (SEM) and high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrosc...

In this work, the photocatalytic properties of amorphous and crystalline TiO2 deposited on oxide and polymer nanoparticles by atomic layer deposition (ALD) were studied. Beside TiO2, as reference, both ALD grown amorphous Al2O3 and crystalline ZnO layers were also examined. When choosing the carrier, the priority was that it had no effect on the ph...

Monolithic structured TiO 2 /aerogel composites were prepared from resorcinol-formaldehyde polymer aerogel (RFA) and its carbon aerogel (RFCA) derivative. A resorcinol-formaldehyde hydrogel was synthesized in a sol-gel reaction and transformed into polymer aerogel by supercritical drying. The RFA was converted to carbon aerogel by pyrolysis at 900...

In this research, we provide first experimental evidence on the dissolution of a thin compound layer sandwiched between the parent materials when it is heated below the order-disorder temperature. The Ta(10 nm)/TaV2(6 nm)/V(30 nm) system, prepared by DC magnetron sputtering, has been chosen to prove the expected simulation results. The samples were...

The solid state reaction between Cu and a-Si films was investigated at 150–200 °C by depth profiling with secondary neutral mass spectrometry. Intermixing was observed leading to the formation of a homogeneous Cu3Si layer at the interface. The growth of the crystalline silicide follows a parabolic law at 165 °C and 200 °C. At 150 °C a transition fr...

For revealing internal atomic processes in bimetallic nanoparticles, individual hemispherical Ag-Cu alloy particles were grown by direct current (DC) magnetron sputtering. Phase separation of particles was found to be size- and composition-dependent. Particles smaller than 5 nm in diameter remained as a solid solution of the components for all test...

Al2O3 (5 nm)/Si (bulk) sample was subjected to irradiation of 5 keV electrons at room temperature, in a vacuum chamber (pressure 1 × 10-9 mbar) and formation of amorphous SiO2 around the interface was observed. The oxygen for the silicon dioxide growth was provided by the electron bombardment induced bond breaking in Al2O3 and the subsequent produc...

The existence of the miscibility gap in the Cu-Ni system has been an issue in both computational and experimental discussions for half a century. Here we propose a new miscibility gap in the Cu-Ni system measured in nano-layered films by Secondary Neutral Mass Spectrometry. The maximum of the symmetrical miscibility curve is around 780K at Cu50%Ni...

Carbon nanospheres (CNSs) were prepared by hydrothermal synthesis, and coated with TiO2 and ZnO nanofilms by atomic layer deposition. Subsequently, through burning out the carbon core templates hollow metal oxide nanospheres were obtained. The substrates, the carbon-metal oxide composites and the hollow nanospheres were characterized with TG/DTA-MS...

Kirkendall effect has been studied experimentally as well as theoretically for decades already. There are theoretical indications, that the Kirkendall effect must operate from the beginning of the diffusion process but there are practically no measurements on this short time and length scale. For that reason, diffusion on the nanometer scale was in...