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Research activity and fields of interest

Overview

The profile of the electrochemistry laboratory is determined by goal of the institute itself; namely, the pursuit of doing reserach devoted to solid state science. Therefore, most of the experiments serve the ait to produce some samples that have peculiat properties falling into the interest of a soid state physicists. This pursuits governs my activity in the field of the electrodepostion of nanocrystalline metals, metallic multilayers, nanowires and various alloys. Beside the preparation of samples with novel properties, sometimes it is possible to use electrochemical methods to measure solid state properties of a sample. This is the case when the electrochemical hydrogen permeation is used to assess the hydrogen diffusivity in solid samples. Recently, electrodeposition of nanostructured metals is of topmost interest, including ones with tuneable porosity.

Beside electrochemistry, I deal with various fields of experimental physical chemistry like bal milling and properties of ball-milled nanocrystalline solids. From 2018, I supervise the scanning electron microscope of the institute, which offers a new insight into the research profile of the entire institute with each new sample studied with the microscope.

Below a short overview is given for the most important fields I got the chance to deal with.


Structural studies of electrodeposited metals

Electrodeposited metals are commonly characterized with conventional X-ray diffractometry by which the phases formed, the texture and the crystallite size can be assessed. However, the fitting of the diffraction profiles and the application of transmission electron microscopy has developed so much that the defect structure of electroplated metals can be characterized in a much larger depth than before. Our laboratory is a part of a network that aims at the detailed structural study of the defect srtucture of metals, characterizing also the twin fault formation probability, dislocation density etc. in order to understand to formation of the crystal structure during electroplating.

Scanning electron microscopy

I have been the suprvisor of the scanning electron microscope of the institute since 2018. The instrument is an up-to-date device with both secondary and backscattered electron detectors as well as an energy dispersive analyzer. It can be used for a large variety of imaging and analysis problems at the nanoscale. The SEM instrument is operated in an open laboratory scheme that makes it available for the entire research community as well as external users on a paid service basis.

Electrodeposition of metallic multilayers

The most important field of my research activity between 1998-2012 was the electrodeposition of samples with alternating magnetic / non-magnetic layers. The thickness of the individual layers typically falls in the 0.5-6 nm range; i.e. a full coverage has to be attained even if only 2 or 3 atomic layers are deposited.

As for the preparation of such multilayers, we use the so-called single-bath method, in which one solution contains the ions of both metals to be deposited, but the concentration of the ions of the non-magnetic metal is 1 to 2 orders of magnitude smaller than that of the other metal. The multilayer structure can be achieved by using square-shaped current or potential pulses. The mixed potentiostatic-galvanostatic deposition method with an unlimited number of sublayers has also been elaborated.

The samples deposited were studied with different methods (XRD, EDX, AFM). Besides the structural analysis, the main goal of the research was the investigation of the magnetoresistance of the electrodeposited samples. In our laboratories, the magnetoresistance can be measured in the 10-300 K temperature range. Giant magnetoresistance has found an application in reading at a high rate the information stored on magnetic disks. Our primary interest was to elucidate the relationship between deposition parameters, the magnetoresistance of the deposits and the structural information obtained with various methods.

Composition depth profile analysis of electrodeposited alloys

Composition depth profile analysis with destructive (sputtering-based) methods reveal valuable information on the component distribution of the alloy components. During electrodeposition of an alloy, a transient layer is formed in which the composition changes before achieving a steady-state. This transien layer was efficienty studied by a method developed in-house to remove the substrate of the deposits and to start the analysis from the substrate side. With this method, the variation of the composition and its spontaneous fluctuation could be detected with an unprecedented accuracy.

Hidrogen absorption and diffusion in metals

Hydrogen absorption, storage in and extraction from metals has long been a major challenge for the energy industry. Besides the storage of hydrogen, it is very important to mention the impact of hydrogen to structural materials. A typical example is the hydrogen embrittlement of ferrous alloys. Between 2000 and 2002, I dealt with the effect of hydrogen to the enamel behavior of modern steels in the framework of an industrial contract. Later, this project was continued and the research consortium was widened by many enamel and steel companies. These projects involve the exact solution of diffusion equations, computer simulation of the effect of the traps and the experimental determination of the hydrogen diffusion coefficient in the metals as a function of temperature. The ultimate goal of this project was to develop a procedure which is appropriate to test the enamelability of some steel types under industrial conditions. The electrochemical permeation workstation (cell and power source) elaborated together with the measurement method was adapted in the research laboratory of the largest Hungarian steel company.

In 2017-2019, our laboratory was an affiliated partner of a project related to materials scicence of zirconium used in nuclear reactors. Our task was to provide highly hydrogenated zirconium samples for further studies.

Industrial projects

Delighted are the moments when the real world enters a research laboratory. Therefore, I am always glad when I can work on industrial probblems. My industry-related experience is rich: I used to build a lab-scale model decvice of a hundred meter long industrial steel pickling unit, cooperated with an aluminum manufacturing company with measuring their samples and developed analytical methods with colleagues from a pharmaceutical company. All problems are potentially within the range of my interest in which interdisciplinary phenomena comprising physical chemistry take some part.

Other methods, procedures and phenomenon

Besides the aforementioned fields, many other electrochemical phenomenon meet my interest, mostly those which involve some other physical aspect as well. As a summary, any field of the applied electrochemistry can be a potential field of interest which exhibits some physical aspect, especially from the field of solid-state physics. My recent pursuits refer to the electrodepositon of porous materials.