On 17, June 2016 in Ural Federal University two Ph.D. defenses in specialty 01.04.07 – Condensed-matter physics: «Piezoelectric, pyroelectric and elastic properties of diphenylalanine microtubes» by Vasilev Semen and «Creation and investigation of optical waveguides with regular domain structure in lithium niobate» by Neradovsky took place in one day. On 24, June 2016 Kosobokov Mikhail also defended his Ph. D. «Formation of micro- and nano-domain structures in lithium niobate and lithium tantalate after transient laser heating» in the same specialty.
Semen Vasilev on basis of a detailed investigation of growth kinetics selected optimal parameters for diphenylalanine microtubes cultivation and explained the experimentally found stick-slip growth of microtubes in frames of a model of a diffusion-controlled aggregation. Pyroelectric effect for the first time found by him is of a special interest which along with visualization of a domain structure permitted to speak in favor of ferroelectric properties of diphenylalanine microtubes. Prototyping of piezoelectric resonators and investigation of its properties demonstrated that diphenylalanine microtubes can be used for creation of biocompatible micro-resonators.
Mikhail Kosobokov experimentally and in detail investigated kinetics of domain structure formation in lithium niobate during impulse laser heating. Qualitatively new dendrite domains in lithium tantalate were discovered by Mikhail while the performed calculations of change of pyroelectric field spatial distribution made it possible to propose an original model for explanation of the discovered effect. The obtained experimental results and the revealed regularity of the domain kinetics made it possible for the first time to obtain constant regular domain structures with a submicron domain width.
Maxim Neradovskiy thesis defence was held in 2 steps: first in Russian, then – in English language. M.Neradovskiy had two scientific supervisor at once: Vladimir Ya Shur, UCSU MN director, UFU Natural Science Institute professor and Marc de Micheli, Nice University professor and besides a degree of physical and mathematical sciences Maxim Neradovskiy was awarded a Ph.D. of Nice University Sophia Antipolis. M.Neradovskiy discovered degradation of regular domain structure due to nanodomain formations with depth of up to 15 micron in grade channel waveguides, for the first time a gigantic decrease of nucleation threshold field in grade waveguides was found, discrete switching of polarization in lithium niobate with staged planar waveguides was revealed, an effect of isotropic domain growth during electron bean irradiation of lithium niobate with gradient planar waveguide was found, a possibility of creation of regular domain structure by means of a focused electron beam in lithium niobate with channel SPE waveguides was demonstrated and the second harmonic generation of laser irradiation with a wavelength in pass band line for telecommunication systems was obtained.
Scientists from Nice University – Sophia Antipolis and Natural Science Institute of Ural Federal University have been interrelated for more than 10 years with joint studies and mutual scientific visits. Double Ph.D. degree and investigations of Maxim Neradovskiy is a good example of a really effective international collaboration where both a material base and knowledge from both sides complemented each other.
28 June 2016