Electrodeposition of copper on copper single crystal (100), (110) and (111) planes in presence of Thiosemicarbazide

Thiosemicarbazide (TSC), present in small quantities in acid copper sulphate bath, modifies the growth habits of copper on copper single crystal planes and reduces cathodic polarization. On (100) plane a transition from layer type of growth to ridge type and from ridges to pyramidal type and finally to polycrystalline type was noticed. On (110) plane ridges change to platelet type then finally to polycrystalline type. On (111) plane at low current densities triangular pyramids formed in pure solution transforms to hexagonal pyramids and to polycrystalline type. At high current densities hexagonal pyramids change to layer type, which transforms to nonsymmetrical pyramids and polycrystalline deposit at critical concentration of the addition agent. The transitions noticed depend on the concentrations of TSC and current density. These changes in morphology are attributed to the adsorption of TSC on the substrate.     

ESR study of irradiated single crystal ofp-toluidinium chloride

Electron spin-resonance has been observed in irradiated single crystals ofp-toluidinium chloride. The spectra obtained for different orientations of the crystal are analysed on the basis of the formation of cyclohexadienyl type of radicals. Partially deuteratedp-toluidinium-ND₃ chloride sample was studied to confirm these results. A qualitative study of irradiatedo-toluidinium bromide and the related deuterium labelled compounds has supported the formation of such radicals.     

Role of chloride ions in relation to copper corrosion and inhibition

Corrosion rates of copper single crystal faces are determined in stirred 0·1N sulphuric acid with various chloride ion concentrations. A mechanism is proposed to explain the variation of corrosion rate with Cl^? ion concentration. Up to 7·5 × 10^?3 M Cl^? ions, the stabilities of the crystal faces are in the order (111)>(100)>(110) but this order is changed to (110)>(100)>(111) in presence of 10^?2 M Cl^? ions. The corrosion potentials of the crystal faces are less noble at all concentrations of Cl^? ions and Cl^? ion acts as a cathodic inhibitor. There is no significant orientation effect on the kinetics of dissolution of copper.     

Electron paramagnetic resonance of Mn2+ in (NH4)2SO4 single crystal

Electron paramagnetic resonance investigation of Mn²⁺ in (NH₄)₂SO₄ single crystal is discussed both in paraelectric and ferroelectric phases of the crystal. Mn²⁺ is found to substitute one of the two possible types (α andβ) of NH ₄ ⁺ ions and get associated with the second type of NH ₄ ⁺ vacancy, the vacancy being the second distant neighbour in thebc-plane. As The line joining Mn²⁺ substituted NH ₄ ⁺ site and NH ₄ ⁺ vacancy lies at an angle of 18° from the crystallographicb-axis in thebc-plane. As the temperature is lowered to ? 56° C the crystal becomes ferroelectric and the spectrum in the paraelectric phase splits into two from which it appears that two sets of Mn²⁺ sites which are magnetically equivalent in the paraelectric phase become inequivalent in the ferroelectric phase. The spin Hamiltonian analysis is presented for the spectrum in the paraelectric phase.     

Growth of GaSb single crystal in space

The crystal growth under microgravity condition in space has attracted a lot of attention, for the quality of crystals can be improved under microgravity because it creates an environment where nature convection is suppressed and mass transportation is controlled by diffusion. This is a joint work between Institute of Physics, the Chinese Academy of Sciences and Department of Electronics Engineering, the University of Tokyo. A rod of GaSb single crystal doped with Te, whose diameter is 6 mm and length is 30 mm, was grown in space during the China returnable satellite mission No. 14 in 1992. The research results show that there was no striations in the space-grown crystal part, and furthermore the dislocation density was close to zero in the part where melt was not in contact with quartz wall during the crystal growing in the space, but it increased rapidly after the melt was in contact with the wall. This paper summarizes the growth and research results of the GaSb crystal in detail, and analyzes the influences of microgravity on crystal growth and its potential developments in the future.     

Vladyslav Kyrylovych Dzyadyk (on His 100th Birthday)

Ukrainian Mathematical Journal -     

Torsional waves in piezoelectric (622) crystal plate

Torsional waves generated in a circular piezoelectric infinite plate of crystal class (622) when excited by an electric potential impulse applied between the centre of one of its flat faces and the opposite face, are investigated. The resulting shearing stress and electric potential are calculated.     

Growth of Cu2Cl2 and Cu2Br2 on single crystal faces and polycrystalline copper during dissolution in CuSO4 + H2SO4

Cu₂Cl₂ and Cu₂Br₂ precipitate and crystallise in the form of triangular pyramids and dendrites when Cu is immersed in aerated, acid CuSO₄ solution containing HC1 or HBr. The critical concentration of HC1 or HBr for this precipitation depends on the surface of the copper: Poly-crystalline < (110) < (100) < (111). In the deaerated solution there is no precipitation of Cu₂Cl or Cu₂Br₂ even at a high concentration of HC1 or HBr when only preferential etching occurs.     

Coordination properties of vic-isonitrosoimines in their copper (II) and palladium (II) complexes

Preparation and structural characterization of palladium (II) complexes of ligands III-V and copper (II) complexes of III are reported. The elemental analyses of the complexes show that the metal: ligand ratio is 1:2. The electrical conductance in acetone shows the non-electrolytic nature of the complexes. The diamagnetic character suggests a gross square-planar geometry for the palladium (II) complexes. Copper (II) complexes are paramagnetic with¼eff.～1·90 B.M. Spectral data suggest that in all the complexes the ligand coordinates to the metal (II) symmetrically through isonitroso-nitrogen and imine-nitrogen, forming a five membered chelate ring. Amine-exchange reactions of the complexes are discussed and compared on the basis of their structures.     

Adatom self-diffusion on Pt (100) surface by an ad-dimer migrating

We study the self-diffusion of adatom on Pt(100) surface by molecular dynamics. The metal is modeled by the surface embedded-atom potential. Besides the conventional concerted exchange mechanism, a new exchange mechanism in which an ad-dimer diffuses by a concerted motion of three atoms is observed. The importance is that it could become a dominant diffusion mechanism in some cases.     

Naum Il'ich Akhiezer (on the 100th Anniversary of His Birth)

Ukrainian Mathematical Journal -