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Multifunctional all-oxide nanostructures for electronic applications

Multifunctional all-oxide nanostructures for electronic applications

Reference
IF/00602/2013/CP1162/CT0015
Project Start Date
2014-02-01
Project End Date
2019-01-31
Principal Investigator
Funding Program
Projectos Exploratórios do IF 2013

Abstract

Oleksandr Tkach graduated in Microelectronics and Semiconductor Devices by the National Technical University of Ukraine (Kyiv Polytechnic Institute) in June 1999. In November 1999, he got a PhD scholarship in Solid State Physics by the National Academy of Sciences of Ukraine, which he received until moving to Portugal in September 2000. From January 2002, O. Tkach received a PhD scholarship by Portuguese Foundation for Science and Technology (FCT), SFRH/BD/6624/2001, until he completed a PhD degree in Materials Science and Engineering by the University of Aveiro in September 2005. From June 2007 to February 2012 he was awarded the post-doc fellowship by FCT, SFRH/BPD/34607/2007, performed in the University of Porto. During the MSc thesis, O. Tkach got an experience on preparation by pulsed laser deposition and photovoltaic characterisation of thin films of nanocrystalline silicon in silicon oxide matrix. His PhD study was due to doping effect on structure, microstructure, and dielectric properties of incipient ferroelectric SrTiO3 ceramics, prepared by conventional mixed oxide method. 8-year post-doc research activity of O. Tkach mainly concerns the preparation of high-dielectric-constant, low-loss, and magnetoelectric materials based on SrTiO3 (bilateral GRICES/DAAD project No. D/07/136522), KTaO3, NaTaO3 (FCT project PTDC/CTM/64805/2006) and BiFeO3 (EU FP6 STREP project NMP3-CT-2004-32616 MULTICERAL) ceramics and films and their structural, microstructural, electric and lattice dynamics characterisation. Currently, he has a time limited post-doc contract at the Johannes Gutenberg University of Mainz, Germany, investigating advanced artificial multiferroics. Being thus involved into EU FP7 project NMP3-LA-2010-246102 IFOX, O. Tkach gains experience in contributing to the photoemission-electron-microscopy synchrotron beamtimes, and studying magnetic, magnetoelectric and magneto-optic properties of PMN-PT/Ni and PMN-PT/Fe3O4 structures as well as (La,Sr)MnO3 films. As a result, 2 manuscripts on the effect of piezoelectric PMN-PT substrate on magnetic configuration of Ni nanostructures are submitted. For the moment, 44 papers are published by him as Alexander Tkach in international peer review journals with average impact factor (IF) of 2.72. In 10 of them he is a corresponding author, while in 26 of them he is the first author, lead writer, and principal contributor. During his PhD, O. Tkach has published 9 papers, cited over 100 times. Since obtaining the PhD degree, 35 papers (including 7 papers published as a corresponding author) were published in international peer review journals with an accumulated impact factor of 104 and with over 300 citations. Of these, 2 were published in major Materials Science multidisciplinary scientific journals Advanced Functional Materials (IF=9.765; 1st author from 6 and corresponding author) and Chemistry of Materials (IF=8.238; 1st author from 6), whereas 1 was published in major Physics multidisciplinary journal Physical Review Letters (IF=7.943; 5th author from 6). Moreover, 4 papers were published in the highest impact factor journal in the area of Metallurgy and Metallurgical Engineering and 3 in the area of Materials Science / Ceramics. More 2 papers were published in the second highest impact factor journal in the area of Microscopy. Most of the publications contain important routine work done using x-ray diffraction, scanning electron microscopy, and Raman spectroscopy techniques as well as dielectric, ferroelectric and magnetic characterisations. However, transmission electron microscopy together with electron diffraction and energy dispersive spectroscopy techniques, microwave, time-domain terahertz, infrared and electron-spin-resonance spectroscopy, x-ray absorption fine structure and thermally stimulated depolarisation currents measurements were also used when necessary. At the same time, some of the publications made also a decisive contribution to the advancement of the discipline. Particularly, the publication in Chemistry of Materials reports for the first time an idea to correlate the antiferrodistortive phase transition temperature Ta of doped SrTiO3 with the Goldschmidt tolerance factor as well as a study of oxygen vacancy effect on the Ta. Further, the effect of the Sr vacancies in SrTiO3 with trivalent dopants substituting for divalent Sr ions was deduces and published in Acta Materialia and Applied Physics Letters. The paper in Physical Review Letters introduces a novel concept of the magnetoelectric multiglass, recently confirmed by the publication in Advanced Functional Materials. This concept was created on the base of large variety of dielectric data (partially published in Applied Physics Letters, Acta Materialia and Physical Review B) and magnetic data, including such non-trivial measurements as memory effect, obtained on Mn-doped SrTiO3. The (Sr,Mn)TiO3 compound is found to be a unique material, revealing simultaneously polar glass dielectric and spin glass magnetic anomalies in addition to enhanced antiferrodistortive elastic behaviour. Further, the dielectric and magnetic anomalies were also found for the first time in (K,Mn)TaO3 ceramics and in polycrystalline (Sr,Mn)TiO3 thin films. The latter work was awarded as the Best Poster of the symposium Multiferroic and magnetoelectric materials of E-MRS 2008 Spring Meeting. For the Materials Science environment this constitutes a major achievement as it shows that not only new materials were developed but also in-depth physical analysis was provided. Thus, the investigation of Ta in doped SrTiO3, discovery of the (Sr,Mn)TiO3 system and introduction of magnetoelectric multiglass concept based on its systematic analysis are the main scientific achievements by O. Tkach. Since 2008 O. Tkach has reviewed manuscripts for such international SCI journals as Advanced Functional Materials, Materials Science and Engineering B, Journal of Alloys and Compounds, Microscopy and Microanalysis, Physica Status Solidi - Rapid Research, Journal of Physics: Condensed Matter, and Journal of Physics D: Applied Physics. In 2012 he is included to Editorial Board of the open access journal Dataset Papers in Physics: Condensed Matter Physics.

Institutions

Main Institutions

  • Universidade de Aveiro (UA)

Funding 303.434,15 €

Fundação para a Ciência e a Tecnologia (FCT) - Portugal

50.000,00 €
  • 2014-02-01 a 2019-01-31
  • IF/00602/2013/CP1162/CT0015
Resources

Fundação para a Ciência e a Tecnologia (FCT) - Portugal

253.434,15 €
  • 2014-02-01 a 2019-01-31
  • IF/00602/2013/CP1162/CT0015