Magnetic properties and surface morphology of layered In2Se3 crystals intercalated with cobalt

The magnetic properties of layered Co _x In₂Se₃ crystals electrochemically intercalated with cobalt in an external magnetic field and without a magnetic field and the morphology of the van der Waals surfaces of layers of these crystals have been investigated. It has been found that the ferromagnetic ordering at room temperature is observed only for Co _x In₂Se₃ crystals intercalated in an external magnetic field. These crystals are nanocomposite materials that consist of a layered matrix and arrays of nanorings and nanowires formed from Co nanocrystals on the van der Waals surfaces of the In₂Se₃ layers. Cobalt nanocrystals in Co _x In₂Se₃ crystals have a pyramidal equilibrium shape, which is characteristic of the face-centered cubic crystal structure, and their geometrical sizes are of the order of a few nanometers. The specific features of self-organization of cobalt magnetic nanostructures on the van der Waals surfaces of layered semiconductor crystals during their electrolytic intercalation in a magnetic field and the magnetic properties of these structures have been considered.     

Effect of annealing on the photoelectric properties of single crystals of InSe

The effect of different heat-treatment regimes on recombination processes in n-In_1.03Se_0.97<0.5Zn> was studied by the method of square-wave modulation of light intensity, with subsequent analysis of the experimental data by the least squares method on a computer. The specimens were annealed at a temperature of 360–400°C in a vacuum [1] or Zn vapors [11] for different periods of time. They were then slowly cooled at a rate of 2 deg/min (A) or quenched (B). It was established the lifetime of the nonequilibrium carriers increases by nearly an order of magnitude in case IB, while the ratio of s- and r-centers remains nearly the same. In case IIA, _s decreases roughly by a factor of two, while in the best specimens it reaches 2.3·10^–5 sec. Annealing for 20 h in regime IA leads to a large increase (by about 25%) in the density of s-centers.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 61–64, November, 1990.     

X-ray diffraction investigation of the structure of propolis films

The structure of films of a biological organic material (propolis) on inorganic substrates is investigated for the first time. It is established that, despite the complex chemical composition (involving more than 300 different components), the propolis films prepared from an alcohol solution on amorphous glass substrates and on semiconductor substrates with a small number of dangling bonds have a crystal structure.     

X-ray diffraction study of the molecular propolis films deposited from an alcohol solution onto the cleavage surfaces of layered V<Subscript>2</Subscript>VI<Subscript>3</Subscript> compounds

The structures of the molecular propolis films deposited from an alcohol solution on the (0001) cleavage surface of layered bismuth selenide and telluride are studied by X-ray diffraction. Despite the chemical interaction between the semiconductor substrates and the organic-substance components, the molecular structural ordering of the propolis films is shown to be identical to that in the films of this substance on the surface of amorphous glass substrates. The chemical and deformation interaction between the organic substance and the layered V₂VI₃ compounds is found to result in the formation of an organic-inorganic sandwich nanostructure at a distance of ∼0.3 μm from the layered crystal-propolis film interface.     

On the possibility of the exciton-phonon bound states in GaSe

The experimental results of the optical absorption and the photoconductivity of GaSe layered crystals in the exciton region are presented. On the basis of the results obtained, we conclude the existence of the exciton-phonon quasibound states.