Features and problems of investing by individuals in Russia

This paper examines the features in the Russian Federation, compares with the actions of investors in Europe and the United States. To study the problems of investing in the Russian Federation, economic and historical features are studied

Vanadium pentoxide (V2O5): a van der Waals density functional study

The past few years has brought renewed focus on the physics behind the class of materials characterized by long-range interactions and wide regions of low electron density, sparse matter. There is now much work on developing the appropriate algorithms and codes able to correctly describe this class of materials within a parameter-free quantum physical description. In particular, van der Waals (vdW) forces play a major role in building up material cohesion in sparse matter. This work presents an application to the vanadium pentoxide (V2O5) bulk structure of two versions of the vdW-DF method, a first-principles procedure for the inclusion of vdW interactions in the context of density functional theory (DFT). In addition to showing improvement compared to traditional semilocal calculations of DFT, we discuss the choice of various exchange functionals and point out issues that may arise when treating systems with large amounts of vacuum.Comment: 5 pages, 4 figures, 1 tabl

Self-lubricious tool coatings for ecological metal cutting

Transition metal oxide Magnéli phases are traditionally described as crystallographic shear structures. Some of these phases feature a layered crystal structure based on deformed metal–oxygen octahedra. Here, the correlation between structure, decohesion energies and elastic properties of several transition metal oxides is described using ab initio calculations. First, seven different vanadium oxides VOx (1 4 exhibit low C44 values, large anisotropy and possess weak ionic bonding between the layers. The formation of easily plastically deformable structures is enabled by the screened Coulomb potential. The largest distance and therefore weakest bond strength is observed for V2O5 in the (002) plane. Studies have then been extended to WO3, ReO3, MoO2, VO2, V2O5 and TiO2, showing that the decohesion energies and elastic constants C44 are inversely proportional to the original distance between the cleaved layers and correspond to the screened Coulomb potential. This can be understood based on the electronic structure. The bond strength decreases rapidly as the distance is increased, resulting in weak coupling between the layers which in turn causes the formation of easily plastically deformable structures, for instance WO3 or V2O5. The fact that structures such as WO3 can also be described by the above-presented correlations provides the basis for quantum mechanical guided design of Magnéli phase structured solid lubricants, based on tailoring the layer distance by varying the chemical composition. A combinatorial method was employed to grow TiAlN–WNx films by DC sputtering as well as by High Power Pulsed Magnetron Sputtering (HPPMS) where the W concentration was varied between 10 to 52 at.% and 7 to 54 at.%, respectively. Experiments were paired with ab initio calculations to investigate the correlation between composition, structure and mechanical properties. As the W concentration was increased, the lattice parameter of cubic TiAlN–WNx films first increased and then decreased for W concentrations above ~29 at.% (DCMS) and ~27 at.% (HPPMS) as the N concentration decreased. Calculations helped to attribute the increase to the substitution of Ti and Al by W and the decrease to the presence of N vacancies. Young’s modulus and hardness were around 385 to 400 GPa and 29 to 31 GPa for DCMS and 430 to 480 GPa and 34 to 38 GPa for HPPMS, respectively, showing no significant trend as the W concentration was increased, whereas calculations showed a continuous decrease in Young’s modulus from 440 to 325 GPa as the W concentration was increased from 0 to 37.5 at.%. The presence of N vacancies was shown to increase the calculated Young’s modulus. Hence, the relatively constant values measured may be understood based on N vacancy formation as the W concentration was increased. HPPMS-deposited films exceeded DCMS films in Young’s modulus and hardness, which may be a consequence of the larger degree of ionisation in the HPPMS plasma. It is reasonable to assume that especially the ionised film forming species may contribute towards film densification and N vacancy formation

Self-lubricious tool coatings for ecological metal cutting

Transition metal oxide Magnéli phases are traditionally described as crystallographic shear structures. Some of these phases feature a layered crystal structure based on deformed metal–oxygen octahedra. Here, the correlation between structure, decohesion energies and elastic properties of several transition metal oxides is described using ab initio calculations. First, seven different vanadium oxides VOx (1 4 exhibit low C44 values, large anisotropy and possess weak ionic bonding between the layers. The formation of easily plastically deformable structures is enabled by the screened Coulomb potential. The largest distance and therefore weakest bond strength is observed for V2O5 in the (002) plane. Studies have then been extended to WO3, ReO3, MoO2, VO2, V2O5 and TiO2, showing that the decohesion energies and elastic constants C44 are inversely proportional to the original distance between the cleaved layers and correspond to the screened Coulomb potential. This can be understood based on the electronic structure. The bond strength decreases rapidly as the distance is increased, resulting in weak coupling between the layers which in turn causes the formation of easily plastically deformable structures, for instance WO3 or V2O5. The fact that structures such as WO3 can also be described by the above-presented correlations provides the basis for quantum mechanical guided design of Magnéli phase structured solid lubricants, based on tailoring the layer distance by varying the chemical composition. A combinatorial method was employed to grow TiAlN–WNx films by DC sputtering as well as by High Power Pulsed Magnetron Sputtering (HPPMS) where the W concentration was varied between 10 to 52 at.% and 7 to 54 at.%, respectively. Experiments were paired with ab initio calculations to investigate the correlation between composition, structure and mechanical properties. As the W concentration was increased, the lattice parameter of cubic TiAlN–WNx films first increased and then decreased for W concentrations above ~29 at.% (DCMS) and ~27 at.% (HPPMS) as the N concentration decreased. Calculations helped to attribute the increase to the substitution of Ti and Al by W and the decrease to the presence of N vacancies. Young’s modulus and hardness were around 385 to 400 GPa and 29 to 31 GPa for DCMS and 430 to 480 GPa and 34 to 38 GPa for HPPMS, respectively, showing no significant trend as the W concentration was increased, whereas calculations showed a continuous decrease in Young’s modulus from 440 to 325 GPa as the W concentration was increased from 0 to 37.5 at.%. The presence of N vacancies was shown to increase the calculated Young’s modulus. Hence, the relatively constant values measured may be understood based on N vacancy formation as the W concentration was increased. HPPMS-deposited films exceeded DCMS films in Young’s modulus and hardness, which may be a consequence of the larger degree of ionisation in the HPPMS plasma. It is reasonable to assume that especially the ionised film forming species may contribute towards film densification and N vacancy formation