Andreeva O. Point defects in the crystalline systems of different dimension (3D - PbIn, 2D - NbSe2)

Object: point defects (vacancies, doping element atoms) in crystalline systems of different dimension (Pb - In and NbSe2). Purpose: establishment of detailed features of the influence of alloying element atoms on the structure and, structure-sensitive properties of substitutional solid solutions Pb - In and layered single crystal NbSe2 with vacancies Se.Methods: X-ray diffraction methods, plastic deformation, isothermal annealing, calculations of partial range order parameters and projections of static displacements of atoms, quantification of the vacancies concentration. Results it is found for the first time that with indium concentration from 5 at.% to 20 at.% In Pb - In alloys short-range order of bundle type is formed: indium atoms - are clustered. With indium content increase in the alloy size and the average density of clusters decreases, and their quantity grows. Clusters increase the yield strength of the alloy and reduce its plasticity. It is experimentally proved that NbSe2 single crystals annealing in the temperature range 443 K - 463 K forms selenium vacancies and their conglomerates that cause a change in the structural modification of the crystal from 2H to 4H. It is found that under the penetration into NbSe2 crystal vacancies distribution is inhomogeneous. Field of application: solid state physics, physics of plasticity, physics of low-dimensional systems