V. M. Puzikov

Impact of incorporated anatase nanoparticles on the second harmonic generation in KDP single crystals

The second harmonic generation efficiency was studied for the single crystalline potassium dihydrogen phosphate matrix with incorporated TiO2 nanocrystals in the field of the mode-locked Nd:YAG laser pulses. For the first time the frequency conversion efficiency gain was observed for KDP:TiO2 single crystal (SC) instead of KDP SC due to the internal self-focusing effect of the pump beam caused by the giant cubic nonlinear optical response of the embedded nanoparticles.

Growth and characterization of Ca9Ln(VO4)7 crystals (Ln = Y, La, or Gd)

Ca9Ln(VO4)7 single crystals (Ln = Y, La, or Gd) have been grown by the Czochralski method. The grown crystals deviate from the stoichiometric ratio Ca/Ln; this deviation increases in the series from Y to Gd.

Low-temperature production of silicon carbide films of different polytypes

The study is concerned with the effect of temperature on the structure of SiC films formed by deposition of the C and Si ions with the energy 120 eV. On the basis of the X-ray structural studies, it is unambiguously established that the structure of the growing polytype is finely dependent on the substrate temperature. In the temperature range from 1080°C to 1510°C, the sequence of films involving the 21R, 51R, 27R, and 6H polytypes is produced for the first time. The effect of temperature on the silicon-carbon atomic content ratio [Si]/[C] in the deposited films is determined. At optimized parameters of deposition the film structured as the 51R rhombohedral polytype is grown.

Potassium and ammonium dihydrogen phosphates activated with thallium: Growth and luminescence and scintillation properties

The conditions for the growth of potassium dihydrogen phosphate (KDP) and ammonium dihydrogen phosphate (ADP) crystals with concentrations of the thallium activator in the initial solution of 0.01, 0.1, and 1.0 wt % are investigated. It is shown that the character of incorporation and distribution of thallium in the KDP and ADP lattices is limited, apparently, by the difference in the ionic radii of K+, NH4+, and Tl+ cations and the charge state of prismatic {100} and pyramidal {101} growth planes. Doping of KDP and ADP with thallium (to 0.1 and 1.0 wt %, respectively) does not deteriorate the structural quality of these crystals. The dependence of the lattice parameters a and c on the thallium impurity concentration is investigated. The absorption bands of thallium in the KDP:Tl+ and ADP:Tl+ crystals peak at 218 and 215 nm, respectively, while the photoluminescence band peaks at 280 nm for both types of crystals. The relative light yield upon excitation of scintillations by α particles (Pu239) and β particles (Bi207) is measured.

Peculiarities of the growth of PbWO4:Nd3+ and PbMoO4:Nd3+ single crystals

The dependence of the Nd segregation coefficient on Nd concentration in PbWO4 and PbMoO4 melts and on the method of its introduction is analyzed. In a study of the PbMoO4-Nd2(MoO4)3 pseudobinary system, the existence of the PbNd4(MoO4)7 compound is established for the first time. Its structure is identified, the melting temperature and character are determined, and a single crystal is grown. The dependences of the damage threshold and anomalous biaxiality angle of PbWO4:Nd3+ and PbMoO4:Nd3+ crystals on the concentration of the activator and the method of its introduction are investigated.

Growth of KH2PO4 crystals activated by organic phosphors

The conditions for growth of single crystals of potassium dihydrogen phosphate KH2PO4 activated by organic phosphors were investigated. Aqueous solutions of derivatives of naphthalic and perylenetetracar-boxylic acids were used as activators. A possible scheme of coherent matching of crystallochemical parameters of the KH2PO4 lattice with an organic activator molecule is proposed. The excitation and photoluminescence spectra of the activated crystals are measured in the range 200–600 nm. It is ascertained that the luminescence is related to the presence of organic phosphors in the KH2PO4 lattice.

Optical and electro-optical properties of ZnMgSe single crystals

The optical and electro-optical properties of large-sized (diameter, 20 mm; length, 70 mm) single crystals of Zn1 − xMgxSe (x ∼ 0.5) semiconductor solid solutions are investigated. The crystals are grown by the vertical Bridgman-Stockbarger method. It is found that, for ZnMgSe single crystals with a magnesium content up to 25 at. %, the modulus of the difference between the electro-optical coefficients |r13 − r33| at a wavelength of 0.63 μm is equal to (1.1 ± 0.22) × 10−12 m/V, which is comparable in order of magnitude to the difference in the electro-optical coefficients for classical hexagonal AIIBVI compounds, such as CdS and CdSe. It is shown that single crystals of ZnMgSe solid solutions are promising materials for use in the fabrication of electro-optical modulators, λ/4-and λ/2-wavelength plates, and multifunctional optical elements operating in the range of high-intensity radiation of CO and CO2 lasers.

Fabrication of Heterostructures Based on Layered Nanocrystalline Silicon Carbide Polytypes

The study demonstrates the possibility of forming heterostructures consisting of nanocrystalline SiC layers of the cubic 3C polytype (the lower layer on the substrate) and the rhombohedral 21R polytype (the upper layer) by direction deposition of nanocrystalline SiC layers onto a substrate subjected to gradient heating. The structure and order of arrangement of the SiC layers are analyzed in detail by X-ray diffraction studies, femtosecond photoluminescence measurements, and optical spectroscopy. The nature of the peaks observed in the photoluminescence, optical reflectance, and absorption spectra is discussed.

Growth of sapphire crystals for optoelectronics from alumina in a protective medium

This paper reports on the results obtained during the development of the technological process of growth of sapphire crystals for optoelectronics through horizontal directional crystallization in a gaseous argon medium at a pressure of 800 mmHg. The sapphire crystals intended for the use in optoelectronics have been grown from purified molten alumina according to the authors’ technology. It has been demonstrated that, under conditions of a high temperature gradient across the crystallization front and at a low content of reducing components (H2, CO) in the growth medium, it is possible to grow sapphire crystals satisfying the requirements of optoelectronics.

Effect of doping method on the formation of charge-compensating defects in PbMoO4:Nd3+ crystals

PbMoO4:Nd3+ single crystals have been grown using different doping schemes. Their dielectric properties have been studied in the temperature range of 20–550°C at frequencies from 25 to 106 Hz. The activation energies of dielectric relaxation are determined for all samples, and the Nd3+ luminescence decay kinetics is studied. The most realistic models of activator centers in PbMoO4:Nd3+ crystals are proposed based on the optical and dielectric spectroscopy data.