Oleksandr Tkach

Assistant Researcher

short cv

- Dr. Oleksandr Tkach is a researcher at the CICECO - Aveiro Institute of Materials, Department of Materials and Ceramic Engineering, University of Aveiro. He works in the field of Materials Science & Engineering and Solid State Physics. A particular area of his scientific activity is related to oxide electroceramics. Present research interests of Dr. Tkach include the development of thermoelectric and piezoelecric oxide materials and composites for energy harvesting technologies; giant permittivity dielectric oxides for energy storage; nanostructured magnetoelectrics for sensor and electronic applications; and alternative energy efficient concepts for current assisted ceramic sintering.

- Oleksandr Tkach graduated in Microelectronics and Semiconductor Devices by the National Technical University of Ukraine “Kyiv Polytechnic Institute” in June 1999, investigating nanocrystalline silicon for optoelectronic applications.
In September 2005 he got his Ph.D. in Materials Science & Engineering from the University of Aveiro, Portugal, studying strontium titanate based ceramics for tunable device applications under a personal PhD grant by Portuguese Foundation for Science and Technology (FCT).
Completion of PhD was followed by an award of Experienced Research position within Marie Curie research training network MULTIMAT to be realized by Dr. Tkach at the University of Barcelona. However, being Ukrainian citizen not supported in obtaining Spanish work visa, he had to return to Aveiro for 1.5 year post-doctoral fellow on multiferroics investigation, participating in EU FP6 STREP project MULTICERAL and European Network of Excellence FAME and contributing to 2 invited talks.
In June 2007 Dr. Tkach won a personal post-doctoral grant by FCT to work at the University of Porto on alkali tantalates and other perovskite ceramics and thin films, contributing to 2 FCT I&D projects and to an awarded poster done within bilateral Portugal/Germany project.
In December 2012, he got post-doc contract at the Johannes Gutenberg University of Mainz, Germany, within EU FP7 project IFOX and ERC project MASPIC, investigating artificial multiferroic heterostructures and contributing to the photoemission-electron-microscopy synchrotron beam-times.
In February 2014 Dr. Tkach was promoted to Assistant Researcher position at the University of Aveiro, CICECO, coordinating FCT Independent Researcher project, acknowledged in his 25 papers, 4 book chapters and 10 invited talks and used for hiring 2 post-doc fellows with Dr. Tkach as a solely supervisor for them as well as for 1 Master student. There are more 8 Master and 1 post-doc co-supervisions by Dr. Tkach. Besides being the FCT and CICECO internal project PI, Dr. Tkach participated in 2 COST actions TO-BE and NETPORE, 3 FCT I&D projects BioMEMs, FLEXIDEVICE and PIEZOFLEX, and 2 projects with industry SGH and AM4SP; contributed to organization of 4 scientific events, more 4 invited talks and 1 awarded poster; edited a book published by Nova Science Publishers; joined Editorial boards of 6 and reviewed manuscripts for >50 scientific journals.  In overall, Dr. Tkach has participated in 3 European, 8 Portuguese FCT and 2 projects with industry as well as 2 bilateral projects with aggregate amount over 48 M€.

- Dr. Tkach publication profile contains 1 edited book, 7 book chapters and 107 articles, including papers in high impact factor (IF) Advanced Functional Materials (IF=19.924), Nature Physics (IF=19.684), Journal Materials Chemistry A (IF=14.511), Carbon (IF=11.307), Chemistry of Materials (IF=10.508) and Journal of Materials Science and Technology (IF=10.319). From his 47 publications in the top quartile JCR SCI journals in their areas, 20 papers are published in the in the top 5 journals of their areas. Four publications by Dr. Tkach were highlighted as the feature or editor choice articles, one in J. Mater. Chem. C 6 (2018) 2467 was selected for the 2018 HOT Papers themed collection, and two were selected for reproduction in book “100 Years of Ferroelectricity 1921 – 2021” by World Scientific. Dr. Tkach is first author, lead writer, and principal contributor on 48/4 and corresponding author on 35/4 papers/chapters.

Ongoing Supervisions



Oxygen vacancies as a link between the grain growth and grain boundary conductivity anomalies in titanium-rich strontium titanate

Tkach, A; Amaral, L; Vilarinho, PM; Senos, AMR

Low loss tunable dielectric BaNd2Ti5O14- (Ba0.5Sr0.5)TiO3 composite thick films

Vilarinho, PM; Fu, Z; Kingon, AI; Tkach, A
2018, SCRIPTA MATERIALIA, 155, 160-163.

Abnormal Grain Growth as a Method To Enhance the Thermoelectric Performance of Nb-Doped Strontium Titanate Ceramics

Tkach, A; Resende, J; Saravanan, KV; Costa, ME; Diaz-Chao, P; Guilmeau, E; Okhay, O; Vilarinho, PM

Interface-based reduced coercivity and leakage currents of BiFeO3 thin films: A comparative study

Tomczyk, M; Mahajan, A; Tkach, A; Vilarinho, PM
2018, MATERIALS & DESIGN, 160, 1322-1334.

Strain-Mediated Substrate Effect on the Dielectric and Ferroelectric Response of Potassium Sodium Niobate Thin Films

Tkach, A; Santos, A; Zlotnik, S; Serrazina, R; Okhay, O; Bdikin, I; Costa, ME; Vilarinho, PM
2018, COATINGS, 8, 12.

Polar phonons in polycrystalline SrTiO3 thin films: The role of the substrate

Okhay, O; Tkach, A; Nuzhnyy, D; Petzelt, J; Vilarinho, PM
2018, FERROELECTRICS, 532, 1, 89-99.

Dielectric spectroscopy and magnetometry investigation of Gd-doped strontium titanate ceramics

Tkach, A; Amaral, JS; Vitor, SAB; Vilarinho, PM
ISBN: 1873-619X

Giant dielectric permittivity and high tunability in Y-doped SrTiO3 ceramics tailored by sintering atmosphere

Tkach, A; Okhay, O; Almeida, A; Vilarinho, PM
2017, ACTA MATERIALIA, 130, 249-260.
ISBN: 1873-2453

Modification of magnetic anisotropy in Ni thin films by poling of (011) PMN-PT piezosubstrates

Tkach, A; Kehlberger, A; Buttner, F; Jakob, G; Eisebitt, S; Klaui, M
2016, FERROELECTRICS, 499, 1, 135-142.

Thin film versus paper-like reduced graphene oxide: Comparative study of structural, electrical, and thermoelectrical properties

Okhay, O; Goncalves, G; Tkach, A; Dias, C; Ventura, J; da Silva, MFR; Goncalves, LMV; Titus, E

Metal Oxide Based Thermoelectric Materials

In Vijay Kumar, Irfan Ayoub, Vishal Sharma, Hendrik C. Swart (Eds.), Optical Properties of Metal Oxide Nanostructures
Olena Okhay and Alexander Tkach
2023, 399-430, Singapore , Springer Nature Singapore Pte Ltd..
ISBN: 978-981-99-5639-5

Antiferrodistortive phase transition in doped strontium titanate ceramics: the role of the perovskite lattice vacancies

In J. Clabel and V. Rivera (Eds.), Perovskite Ceramics
Alexander Tkach
2022, 77-98, Elsevier.
ISBN: 978-0-323-90586-2

Nonstoichiometry Role on the Properties of Quantum-Paraelectric Ceramics

In Tanasescu, S. (Eds.), Structure Processing Properties Relationships in Stoichiometric and Nonstoichiometric Oxides
Tkach, A; Vilarinho, PM
2020, London, IntechOpen.
ISBN: 978-1-78985-452-7

Strain effect on the properties of polar dielectric thin films

In Alexander Pogrebnjak and Valentin Novosad (Eds.), Advances in Thin Films, Nanostructured Materials, and Coatings
Tkach, A; Okhay, O; Santos, A; Zlotnik, S; Serrazina, R; Vilarinho, PM; Costa, ME
2019, 331-342, Springer Nature Singapore Pte Ltd.
ISBN: 978-981-13-6132-6

Sr/Ti ratio in strontium titanate ceramics: designing the microstructure, envisaging the properties

In Alexander Tkach and Paula Vilarinho (Eds.), Strontium Titanate: Synthesis, Properties and Uses
Amaral, L; Tkach, A; Vilarinho, PM; Senos, AMR
2019, 71-100, New York, Nova Science Publishers, Inc.
ISBN: 978-1-53615-437-5

Effect of bismuth doping on the properties of strontium titanate thin films

In Alexander Tkach and Paula Vilarinho (Eds.), Strontium Titanate: Synthesis, Properties and Uses
Okhay, O; Tkach, A; Vilarinho, PM
2019, 209-258, New York, Nova Science Publishers, Inc.
ISBN: 978-1-53615-437-5

Enhancement of thermoelectric performance in SrTiO3-based ceramics by processing conditions

In Alexander Tkach and Paula Vilarinho (Eds.), Strontium Titanate: Synthesis, Properties and Uses
Tkach, A; Resende, J; Diaz-Chao, P; Guilmeau, E; Costa, ME; Vilarinho, PM
2019, 297-322, New York, Nova Science Publishers, Inc.
ISBN: 978-1-53615-437-5

Functional Tantalum-based Oxides: From the Structure to the Applications

In Ashutosh Tiwari, Rosario A. Gerhardt andMagdalena Szutkowska (Eds.), Advanced Ceramic Materials
S. Zlotnik, A. Tkach, P. M. Vilarinho
2016, 337-283, John Wiley & Sons, Inc.
ISBN: 978-1-119-24244-4

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