Materials Science in Ukraine

In the short historical essay, the ways of formation of Materials Science in Ukraine are considered, and tendencies of its development over the World were taken into account. The outstanding human resources and excellent raw deposit capabilities of Ukraine have led to creating Ukrainian scientific schools back in the days of the Russian Empire, which were comparable to the Ural and another world schools of metallurgists and metal scientists. The further development of science on materials in Ukraine is closely related with establishing the Academy of Sciences in 1918. From the first twelve members of the All-Ukrainian Academy of Sciences, three of them namely V.I. Vernadsky, P.A. Tutkovsky and S.P. Tymoshenko, had represented the natural sciences. The election of E.O. Paton to the Academy in 1929 for "technical sciences" specialty had initiated the usage of promising achievements of fundamental sciences for development of applied ones. Since that, the famous Institutes of Ferrous Metallurgy (1936), Metal Ceramics and Special Alloys (1955) and others were founded. The idea to develop the new area of knowledge, which would combine the different types of interatomic bonding to be resulted in new materials and would not be preferable to metallic materials only, has been already in time, namely in 1963. B.Ye. Paton jointly with I.M. Frantcevych had created the Department of Physical and Technical Problems of Materials Science, which included a few institutes namely: electric welding (Paton Welding Institute, PWI), cermets and special alloys (Institute for Problems of Materials Science (IPMS since 1964), foundry (problems of casting since 1964, and Institute of Physics and Technology Metals and Alloys (PTIMA since 1996), mechanical engineering and automation (Institute of Physics and Mechanics (IPM since 1964). And although the institutions are quite different in their profiles, their uniting direction is materials science. As early as 1963, V.N. Yeremenko was elected as the first academician for the "materials science” specialty. Therefore, the issue of a new collection of scientific papers under the title "Progress in Materials Science" is natural and vitally required. It is corresponding to global trends in the formation of scientific and technical priorities in developed countries and is as the task for Ukraine too.

The Effect of Corrosion on the Natural Frequencies of Beams

Corrosion is a natural process of degradation of the mechanical properties of some materials like: metals, ceramics or polymers. The metals and their alloys corrode only because of their presence in a damp environment, but the process is more powerful in some corrosive environments. Corrosion is a diffusion process by which some chemical bonds of the base material are broken, and therefore the oxides, bases, or salts are formed, resulting in a process of mass loss but also of weak interatomic bonding forces, that means a loss of stiffness. Mass distribution and stiffness in a mechanical structure determine the natural frequencies and shape of natural modes, that is, so-called modal parameters that characterize its dynamic behavior. The purpose of this paper is to determine the influence of simultaneous loss mass and loss stiffness on natural frequencies. Applying the Finite Element Method and the Modal Analysis Module of the ANSYS software, the natural frequencies are obtained in numerical approach, which compares with the obtained analytical values, to confirm the validity of the proposed method.

Complex interplay of interatomic bonding in a multi-component pyrophosphate crystal: K 2 Mg (H 2 P 2 O 7 ) 2 ·2H 2 O

The electronic structure and interatomic bonding of pyrophosphate crystal K 2 Mg (H 2 P 2 O 7 ) 2 ·2H 2 O are investigated for the first time showing complex interplay of different types of bindings. The existing structure from single-crystal X-ray diffraction is not sufficiently refined, resulting in unrealistic short O─H bonds which is rectified by high-precision density functional theory (DFT) calculation. K 2 Mg (H 2 P 2 O 7 ) 2 ·2H 2 O has a direct gap of 5.22 eV and a small electron effective mass of 0.14 m e . Detailed bond analysis between every pair of atoms reveals the complexity of various covalent, ionic, hydrogen bonding and bridging bonding and their sensitive dependence on structural differences. The K--O bonds are much weaker than Mg--O bonds and contributions from the hydrogen bonds are non-negligible. Quantitative analysis of internal cohesion in terms of total bond order density and partial bond order density divulges the relative importance of different types of bonding. The calculated optical absorptions show multiple peaks and a sharp Plasmon peak at 23 eV and a refractive index of 1.44. The elastic and mechanical properties show features unique to this low-symmetry crystal. Phonon calculation gives vibrational frequencies in agreement with reported Raman spectrum. These results provide new insights indicating that acidic pyrophosphates could have a variety of unrealized applications in advanced technology.

Thermal conductivity of monolayer MoS2, MoSe2, and WS2: interplay of mass effect, interatomic bonding and anharmonicity

Our work shows that the thermal conductivity κ of MoS2 is largest among the three materials (Fig. a and b) due to largest Debye temperature. WS2 has stronger bonding (Fig. e) and lower anharmonicity (Fig. h), leading to a much larger κ compared to MoSe2.