L. N. Dem’yanets

Growth of thin ZnO films by ultrasonic spray pyrolysis

We report the growth of high-quality thin ZnO films with controlled microstructure on Si(111) substrates by ultrasonic spray pyrolysis of Zn-containing solutions.

On the possible coexistence of spiral and collinear structures in antiferromagnetic KFe(MoO4)2

The static and resonance properties of a quasi-two-dimensional antiferromagnet phase on a distorted triangular lattice of KFe(MoO4)2 have been experimentally studied. Magnetization curves exhibit features corresponding to the spin-flop transition in a collinear biaxial antiferromagnet and simultaneously show a magnetization plateau characteristic of a triangular spin structure. The magnetic resonance spectra also display absorption lines corresponding to the spin structures of both types. The experimental data are described in terms of a model comprising alternating weakly bound magnetic layers, in which the main two exchange integrals have different values. Below the Néel temperature (TN=2.5 K), some of these layers possess a collinear antiferromagnetic structure, while the other layers have a triangular or spiral structure.

Electric-field effect on crystal growth in the Li3PO4-Li4GeO4-Li2MoO4-LiF system

We have studied the electric-field effect on crystallization processes in the Li3PO4-Li4GeO4-Li2MoO4-LiF system. In zero field, Li3+xP1−xGexO4 (x = 0.31) crystals were grown on the cathode under the conditions of this study. At low applied voltages (≤ 0.5 V), we obtained Li2MoO4, Li2GeO3, and Li1.3Mo3O8. In the range V = 0.5–1 V, crystals of Li3+xP1−xGexO4 solid solutions with x = 0.17, 0.25, 0.28, 0.29, and 0.36 were obtained. An applied electric field was shown to reduce the melting temperature of the starting mixtures and the crystallization onset temperature.

Lasing in hydrothermally grown ZnO nanocrystals

Micro- and nanocrystalline ZnO powders and films have been prepared under mild hydrothermal conditions, and their spectroscopic and lasing properties have been investigated. The polycrystalline ZnO films showed stimulated emission with a lasing threshold of 0.67 MW/cm2. Analysis of their lasing behavior suggests that the stimulated emission is generated by individual crystallites, each acting as a microlaser.

Growth and Raman spectra of doped ZnO single crystals

ZnO:Mn+(Mn+ = Cd2+, Co2+, Ni2+, Sc3+, In3+, Ga3+, Fe3+, Te4+, V5+) single crystals have been grown under hydrothermal conditions in ZnO-MxOy-KOH-LiOH-H2O systems, and their Raman spectra have been measured under visible (514.5 nm) and near-IR (1064 nm) excitation. The anomalous band between 500 and 600 cm−1 in the Raman spectra of ZnO:Mn2+ has A1 symmetry and is due to vibrations involving Mn2+.

Magnetic memory effect in ZnO single crystals

AbstractHardening of ZnO single crystals is found to occur after their treatment in a constant magnetic field (B = 1–2 T). A maximum increase in the microhardness of the crystals is observed within 3–4 h after magnetic treatment. Then, the effect gradually decreases and the microhardness regains its initial value in 2–3 days. It is revealed that the sensitivity of the microhardness to a variation in the magnetic field has a threshold character: the effect appears at a magnetic induction higher than a critical value, rapidly increases in a narrow magnetic field range ΔB (∼0.3 T), and then reaches saturation. It is shown that the magnitude of the effect depends on the orientation of the magnetic field with respect to the polar axis of symmetry of the crystal and is independent of the crystallographic orientation of the measurement plane. The maximum increase in the microhardness (∼20%) is observed for all the (0001), (11

Crystal chemistry of germanates: Characteristic structural features of Li,Ge-germanates

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Mechanism of structural phase transitions in the Li4GeO4-ZnGeO4 system: Computer modeling and identification of invariant nanocluster structures in Li4GeO4, LISICON Li6Zn(GeO4)2, and Li4Zn2(GeO4)2 (γ phase)

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