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Pure and Nd-doped Ca 10 Li(VO 4 ) 7 single crystals were grown by the Czochralski method. The structure of Ca 10 Li(VO 4 ) 7 single crystal was refined starting from a model of Ca 10 K(VO 4 ) 7 using the powder diffraction data collected at a laboratory high-resolution diffractometer. The defect structure of the single crystal was studied with the use of both, high-resolution diffraction using a laboratory instrument and X-ray topographic techniques employing synchrotron radiation at the Hasylab laboratory (Hamburg). Polarized absorption and luminescence spectra of Nd-doped Ca 10 Li(VO 4 ) 7 crystal were investigated in details. The laser oscillation was obtained under flash lamp pumping and the slope efficiency of 0.87% was achieved in the free-running mode. Preliminary examination of lasing properties points that Ca 10 Li(VO 4 ) 7 :Nd crystal can be a highly efficient solid state laser medium. Crystals of this kind are expected to be suitable for application as efficient non-linear optics materials.

The filamentation phenomenon arising at the intersection of two femtosecond laser beams in a sapphire single crystal has been studied. Conditions for a regular multifilament structure (MFS) to emerge with the parameters depending on the pulse energy, intersection angle, and phase difference between two exciting beams are determined. For the first time, the formation of a single filament under the action of two different excitation beams is analyzed as an MFS implementation. The number of filaments in the MFS is demonstrated to depend on the number of interference maxima in the intersection region of beams, the power of which exceeds the critical power of self-focusing. Attention is paid to the possibility to control the multifilament structure by varying the phase difference between the interacting beams. Optical manifestations of the interaction between the filaments with the “attractive” or “repulsive” character are observed. The spectrum of the axial emission by a single filament, as well as its dependence on the filament length, is studied, and the process of four-wave mixing is shown to play a key role in its formation., Дослiджено явище фiламентацiї при перетинi двох фемтосекундних лазерних променiв у монокристалiчному сапфiрi. Визначено умови утворення регулярної мультифiламентної структури (МФС), параметри якої залежать вiд енергiї iмпульсу, кута перетину i рiзницi фаз мiж двома збуджуючими променями. Вперше, як окрему реалiзацiю МФС, дослiджено процес формування одинарних фiламентiв при дiї двох рiзних променiв збудження. Продемонстровано, що число фiламентiв в МФС залежить вiд кiлькостi iнтерференцiйних максимумiв в областi перетину променiв, потужнiсть яких перевищує критичну потужнiсть самофокусування. Звернуто увагу на можливiсть керування мультифiламентною структурою шляхом змiни рiзницi фаз мiж взаємодiючими променями. Спостережено оптичнi прояви “притягувального” i “вiдштовхувального” характеру взаємодiї фiламентiв. Вивчено спектр осьового випромiнювання одинарного фiламента залежно вiд його довжини. Показано, що у формуваннi осьового спектра його випромiнювання визначальну роль вiдiграє процес чотирихвильового змiшування.

We report on the experimental observation of periodic modulation of the axial luminescence intensity along the femtosecond filament track in sapphire and crystal quartz. The physical reason for the modulation is a cyclic transformation of the polarization state of the light pulse traveling in birefringent medium, caused by the phase raid between the ordinary and extraordinary rays, and different cross sections of multiphoton absorption for linear and circular polarizations.

Hexagonal single crystals of the Cr2+:Zn1-xMgxSe solid solution are grown by the Bridgman – Stockbarger technique. We study their optical and photoluminescent characteristics and determine the temperature dependences of the photoluminescence kinetics within the range 5 – 440 K. The crystals possess a broad gain band in the range from 2 to 3.5 μm and exhibit a weak quenching of luminescence with a quantum yield exceeding 80% at room temperature. Tunable continuous-wave oscillation is demonstrated in the region of 2.5 μm.

The absorption and photoluminescence spectra of the solutions and crystals of ADP in the presence of dopant molecules (pH 3.5) and/or anion (pH 5.2) of salicylic acid and Tl + cation are studied. Dissociation of salicylic acid at the first stage is accompanied with the formation of salicylate complexes with thallium phototautomer. It is shown that the dopants are incorporated into the crystal, irrespectively of one another, in accordance with their distribution coefficients. The influence of the process of the impurity co-doping on the growth kinetics of the prismatic (100) ADP faces depends on the stoichiometry of the solution. The neutral H 2 Sal dopant monomers (pH 3.5) increase σ d and diminish the growth rate. The HSal − dopant monoanions (pH 5.2) reduce the amount of σ d and raise the growth rate. Tl + ions in the solution increase σ d and decrease the growth rate irrespectively of the pH. The influence of the HSal − /Tl + co-dopant (pH 5.2) on σ d is almost 1.5 times lower than the one of the H 2 Sal/Tl + co-dopant (pH 3.5); both co-dopants reduce the growth rate. The crystal growth is realized via moving macrosteps.

Single crystals of KDP crystals with embedded Urea molecules and TiO2 nanoparticles have been grown from aqueous solution by the temperature lowering method. The effect of the organic molecules and nanoparticles on the structural and mechanical properties has been studied. It has been observed that addition of Urea molecules improves laser induced damage threshold and mechanical strength of the crystal, while TiO2 nanoparticles have the opposite effect. The structure and composition of KDP:Urea crystal are studied by three-crystal X-ray diffraction analysis, which reveals the existence of a correlation between the increase of the microhardness value and the change of the crystal lattice parameter. The surface features of KDP:TiO2 crystals are analyzed by scanning electron microscopy that reveals the presence of quasi-equidistant growth bands caused by capture of the nanoparticles. It is shown that the rise of TiO2 nanoparticles concentration up to 10−4 wt.% and higher resulted in 3-fold reduction of the laser damage threshold of KDP:TiO2 relative to pure KDP in [001] and [100] crystallographic directions. It is found that microhardness and fracture toughness decrease at the nanoparticles concentration of 10−3 wt.% due to crack formation at crystal lattice discontinuities. The grown crystals also have been subjected to dielectric studies.

Based on analysis of lithium dihydrogen phosphate (LDP) solubility dependence on solution stoichiometry alteration, solvent evaporation rate impact on solution supersaturation change is evaluated. It is revealed that at constant crystal growth rate relative solution supersaturation linearly depends on water evaporation rate. LDP nonstoichiometric saturated solution (20 % H₃PO₄ excess) stability boundary conditions are determined. Water evaporation rate is 0.5 %/24 h and supersaturation σ is 0.6 %/24 h, respectively. LDP nonstoichiometric solutions density and viscosity are measured.

Nanocomposite films containing nanocrystals of silicon and silicon carbide are fabricated by direct ion-beam deposition onto silicon substrates. The films obtained are by Raman spectroscopy and the photoluminescence method. It is found that the samples under study exhibit two photoluminescence bands, in the “red” and near-infrared (IR) (600–1000 nm) and “blue” (400–550 nm) spectral ranges, which are accounted for by, respectively, the radiative recombination of excitons in silicon nanocrystals and radiative transitions between levels related to local centers (defects) on the surface of silicon nanocrystals and in the surrounding matrix. Short-duration treatment of the films in a solution based on hydrofluoric acid leads to modification of the emission spectrum and to an increase in the intensity of the exciton band due to the passivation of defects on the surface of silicon nanocrystals.

Correlations between the optical and structural characteristics of nanocrystalline silicon-carbide (nc-SiC) films prepared by direct ion deposition onto sapphire substrates are studied. The effect of the scattering of electromagnetic radiation in nc-SiC films on their optical characteristics (transmittance, reflectance, and absorbance) is investigated. It is shown that in nc-SiC films deposited at temperatures 1000°C exhibit significant morphological and structural heterogeneity and therefore strongly scatter light. It is established that the account for light scattering leads to a blue shift of the fundamental absorption edge in the optical density spectra. The spectra of the scattering coefficients for the nc-SiC films are studied and calculated. The effect of high-temperature annealing on the film structure and scattering spectra is investigated. It is demonstrated that the structural variations induced by annealing are accompanied by a change of the initial mechanism of Rayleigh scattering in the nc-SiC films for the Mie scattering.

Optical and nonlinear optical properties of a novel composite system based on KDP single crystals with embedded nanoparticles of nanostructured oxyhydroxide of aluminum (Al 2 O 3 · n H 2 O, NOA), were studied. KDP crystals with NOA nanoparticles (KDP:NOA) possess high optical quality and homogeneity. Optical spectroscopy showed the presence of an absorption band at 270 nm caused by NOA nanoparticles incorporated in the KDP matrix. There was observed an enhancement of nonlinear refractive index and inversion of its sign in KDP:NOA crystals in comparison with nominally pure KDP crystals under excitation of picosecond laser pulses. The obtained results demonstrate that KDP:NOA is a promising composite material for optoelectronics and nonlinear optics.

The present paper brie y overviews the application of the Czochralski method for growth of a set of oxide crystals for photonics, as well as the design of equipment at the Institute for Single Crystals, NAS of Ukraine. The examples of crystal growth and their characterization are described. The simultaneous Q-switched lasing and self-Raman frequency conversion were demonstrated in Nd-doped PbWO4 and PbMoO4 crystals grown by the Czochralski method. The slope lasing e ciency obtained for a PbMoO4:Nd 3+ laser is the best result for all the crystals with the scheelite-type structure. A detection unit with high scintillation characteristics based on a large volume (V ≈ 350 cm) CdWO4 crystal was produced. Crystal growth procedures and properties of new double tungstate and vanadate crystals are presented, too.

Studied are peculiarities of the changes in the structure and electrophysical properties of nanocrystalline silicon carbide films of 3C-SiC polytype subjected to the action of picosecond laser pulses with λ = 355 nm and a pulse power up to 1.5 W. It is established that laser processing of the films with an energy density of 3 × 10−2−30 J/cm2 leads to ablation without decomposition of SiC. During the laser processing the electrical resistance of the films rises due to diminution of the film thickness. While measuring the PL properties of nc-SiC films under the influence of the applied electric field with intensity 3 × 103 V/cm, the effect of a single triple enhancement of the luminescence maximum is revealed. Repeated PL measurements at the same area of the film under the applied electric field with the intensity ranging from 0 to 1 × 104 V/cm show that the PL emission intensity diminishes at the short-wavelength boundary of the maximum and rises at the long-wavelength boundary. Thereat the spectral position of the PL maximum remains unchanged.

Lithium dihydrogen phosphate (LiH2PO4, LDP) single crystals were grown from aqueous solutions of orthophosphoric acid. The influence of the concentration of the acid in the mother liquor on the solubility of LDP crystals and the conditions of their crystallization, was studied. The change of LDP solubility with the rise of the temperature was found to be not higher than 5 mass%, irrespective of the acid concentration. The solubility diminished with the increase of the acid concentration in the mother liquor. The conditions of the growth of LDP crystals were analyzed from the viewpoint of the method of creation of the solution supersaturation, e.g. change of the acid concentration or evaporation of the solvent. The latter method is most optimal for the growth of LDP crystals from aqueous solutions of orthophosphoric acid. The habitus of the crystals was established to change with the rise of the acid concentration in the solution: the growth of the faces of the pyramid {111-} and the dome {011-} is suppressed, whereas the face of the pedestal {001-} continues to grow. The model of the influence of hydrogen bonds on the habitus of the crystals was considered.

The triple-crystal X-ray diffractometry of anomalous X-Ray transmission is used to investigate sapphire single crystals grown in protective gaseous media with the help of the horizontal directional-crystallization method. The dependences between the integral intensities of anomalously transmitted and Bragg-Laue reflected X-ray beams (Ti and Ri, respectively) and the thickness of the samples under study, which enable us to determine regions of thin- and thick-crystal approximation, have been obtained at 2.52 ≤ μt ≤ 18.9. The integral coefficient μi of interference absorption and the integral characteristic yi are calculated in the dynamic thick-crystal approximation. It is demonstrated that dislocations are distributed mainly within the small-angle boundaries of a grown sapphire crystal. It is ascertained that the parameter μi is highly sensitive to the dislocation density and the pattern of the dislocation distribution in a crystal.

KDP crystals with incorporated molecules of the luminophore 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt (SPA) were grown from KH 2 PO 4 solutions by the temperature lowering method. The luminescence spectra of KDP/SPA crystals and SPA solutions in distilled water and in KH 2 PO 4 solutions, were studied. The increase of the dye content gives rise to excimer luminescence in the solutions and in KDP crystals, which is due to the formation of associated dye molecules. SPA molecules possessing negative electrostatic potential are incorporated into the pyramidal growth sector of KDP crystal.

The $$\hbox {Ca}_{9}\hbox {RE}(\hbox {VO}_{4})_{7}$$ (RE $$=$$ La, Nd, Gd) and $$\hbox {Ca}_{10}\hbox {M}(\hbox {VO}_{4})_{7}$$ (M $$=$$ Li, Na, K) single crystals have been grown by the Czochralski method. The binary vanadates are isostructural to “whitlockite” mineral (rhombohedral symmetry, R3c space group). Their thermal conductivity has been investigated in the range 50 K–300 K parallel to the c axis. For $$\hbox {Ca}_{9}\hbox {Gd}(\hbox {VO}_{4})_{7}$$ crystals, the thermal conductivity has been investigated in the range 300 K–550 K also. Additionally, for the $$\hbox {Ca}_{10}\hbox {M}(\hbox {VO}_{4})_{7}$$ (M $$=$$ Li, Na, K) crystals the heat capacity has been studied in the temperature range 80 K–300 K. The character of the temperature dependence of thermal conductivity is close to that of glasses. The possible reasons of the observed features of the thermal conductivity have been analyzed. Raman spectra of $$\hbox {Ca}_{10}\hbox {M}(\hbox {VO}_{4})_{7}$$ (M $$=$$ Li, Na, K) crystals have been measured and discussed. The spectral lines were broad and similar to polycrystalline or amorphous solids. These crystals are expected to be suitable for application as efficient nonlinear optic and laser materials.

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.

The work is dedicated to growth by the liquid phase epitaxy method and study of the luminescence and scintillation properties of Sc 3+ doped single crystalline films (SCF) of Lu 3 Al 5 O 12 (LuAG) garnet. The scintillation properties of SCF are compared with single crystal (SC) analogues grown by the Horizontal Direct Crystallization and Czochralski methods. We consider the dependence of intensity of the Sc 3+ emission in LuAG host on the activator concentration and influence of flux contamination on the light yield (LY) of the Sc 3+ luminescence in LuAG:Sc SCF with respect to their SC counterparts and the reference YAP:Ce scintillator. From the NMR investigations of LuAG:Sc SCF we confirm the substitution by Sc 3+ ions both the octahedral and dodecahedral positions of LuAG host and formation of the Sc Al and Sc Lu related emission centers, respectively. We also show that the luminescence spectrum in the UV range and decay kinetics of LuAG:Sc SCF can be effectively tuned by changing the scandium content.

The optical and photoluminescence (PL) properties of nanocrystalline 3C-SiC films and the effect of the boundary regions between the nanocrystals were studied for two sets of films: (a) films with 10–15 nm nanocrystal size obtained by direct ion deposition method and (b) similar films annealed in oxygen at 850–950 °C. It was shown that annealing of the nanocrystalline SiC films resulted in weaker absorption in a broad spectral range, and to the increase of the optical band gap from 1.8 to 2.2 eV. On the contrary, the edge PL bands in the UV range (2.2 to 2.4 eV) remained similar. In the IR range, three maxima absent in the as-grown films, appeared at 1.52 eV, 1.56 eV and 1.63 eV. Measurement of the intensity of PL maxima as a function of the excitation power showed a nonlinear dependence that was attributed to the onset of stimulated emission.

We report experimental study on luminescence and optical properties of single crystals KH 2PO 4 (KDP) doped with Tl + ions (KDP:Tl) carried out at 10-480 K. The 4.5 eV photoluminescence (PL) of KDP:Tl originates from radiative electronic transitions 3P 1 → 1S 0 in the Tl + ions upon excitation by UV-photons, X-rays, and electron beam. This luminescence can be induced by direct photoexcitation, or through the recombination process with participation of the lattice defects located in the vicinity of Tl + ion. These excitation mechanisms lead to different temperature behavior of the luminescence intensity. The PL excitation spectra of KDP crystals containing a small amount of the Tl + ions (0.001-0.008 wt.%) comprises peaks at 5.7-5.8, 6.9, and 7.3-7.4 eV, corresponding subsequently to the A-, B- and C-optical transitions in Tl +. The PL time response has single-exponential behavior with an average lifetime of τ = 280 ± 8 ns. Under exposure to ionizing radiation (X-rays, or electron beam) the intensity of the Tl + luminescence increases depending on the exposure time. The origin of this phenomenon was associated with creation of defects in the hydrogen sublattice of KDP. © 2012 Elsevier B.V. All rights reserved.

SiO2 matrices with incorporated molecules of Rhodamine 6G and Rhodamine 800 laser dyes were synthesized by the sol–gel method. The spectral properties of the matrices were studied. It was found that the incorporation of Rhodamine 6G molecules into the xerogel network decreased their association. The influence of the molar ratio of water and formamide on the transparency of the samples was studied. Laser emission of SiO2 matrices activated with Rhodamine 800 was obtained in the near infrared spectral range. The values of laser spectrum halfwidth of SiO2 matrices with Rhodamine 6G and Rhodamine 800 are 2–6 nm. A well-defined structure of the laser emission spectra of the matrices at microsecond pumping duration testifies to their relatively high optical quality.

The influence of fluorine doping on the luminescent properties of lead tungstate, PbWO4, a scintillating material used in high-energy physics, was studied. Two series of crystals that were grown by the Czochralski method in two different laboratories were investigated. It was shown that the luminescent properties of the fluorine-doped samples were similar although those of the undoped PbWO4 samples from the different series differed significantly. It was concluded that this was associated with the formation of WO3F complexes in the fluorine-doped PbWO4 crystals.

The characterization of new gain-switched Fe:Cr:Zn1-xMgxSe laser working at the room temperature and its comparison to Fe:ZnSe laser was performed. The laser oscillation behavior, generation efficiency and output wavelength tuning possibilities were demonstrated. It was shown that the absorption and luminescence spectra of Fe:Cr:ZnMgSe crystal are shifted towards longer wavelengths in comparison with Fe:ZnSe active material. The difference is approximately 300 nm and it corresponds to measured absorption and emission spectra. The maximal Fe:Cr:ZnMgSe laser generated energy and the slope efficiency with respect to the absorbed energy were 200 ?J and 4.5%, respectively.

ADP–NH 4 Sal hybrid crystals are grown from aqueous solutions. The influence of the acidity of the mixed solution on the conditions of co-crystallization of the components is studied. The spectral and scintillation characteristics are determined. Co-crystallization of ammonium salicylate (NH 4 Sal) and ammonium dihydrogen phosphate (ADP, NH 4 H 2 PO 4 ) is shown to be feasible, the structure of the doping addition being defined by the solution рН. In basic and weak acidic media the hybrid crystals ADP:NH 4 Sal are formed in which salicylate anions are located in the interplanar space between the {110}-type planes in the lattice of ADP. The luminescence spectra contain an emission band maximum with λ max =360 nm. In acidic solutions there are ADP:HSal crystals in which salicylic acid molecules captured by the growth macrosteps are located in the interplanar space of the prismatic {100} and pyramidal {101} growth sectors. The luminescence band undergoes bathochromic shift to λ max =400 nm. The sensitivity of ADP:NH 4 Sal scintillation crystals to fast neutrons depends on the concentration of ammonium salicylate in ADP matrix. The highest neutron sensitivity is characteristic of the co-doped ADP:NH 4 Sal/Tl scintillation crystals.

Luminescence and scintillation properties of Y3Al5O12:Ce single crystals grown from the melt by the Czochralski and horizontal directed crystallization methods in various gas media and Y3Al5O12:Ce single-crystal films grown by liquid-phase epitaxy from a melt solution based on a PbO-B2O3 flux have been comparatively analyzed. The strong dependence of scintillation properties of Y3Al5O12:Ce single crystals on their growth conditions and concentrations of YAl antisite defects and vacancy defects has been established. Vacancy defects are involved in Ce3+ ion emission excitation as the centers of intrinsic UV luminescence and trapping centers. It has been shown that Y3Al5O12:Ce single-crystal films are characterized by faster scintillation decay kinetics than single crystals and a lower content of slow components in Ce3+ ion luminescence decay during high-energy excitation due to the absence of YAl antisite defects in them and low concentration of vacancy defects. At the same time, the light yield of Y3Al5O12:Ce single-crystal films is comparable to that of single crystals grown by directed crystallization due to the quenching effect of the Pb2+ ion impurity as a flux component and is slightly lower (∼25%) than the light yield of single crystals grown by the Czochralski method.

The electrical conductivity and Seebeck effect in ceramics based on cobaltites Ho1 − x Sr x CoO3 − δ (x = 0.65, 0.75, 0.85, 0.95) and Er1 − x Sr x CoO3 − δ (x = 0.75, 0.85, 0.95) with a perovskite-like structure have been investigated in the temperature range T > 77 K. All the compounds under study are characterized by the variable-range-hopping conductivity with the temperature dependence of the electrical resistivity corresponding to the Mott law. It has been found that, in the Ho0.35Sr0.65CoO3 − δ compound, thermally excited Co3+ ions contribute to the electrical conductivity with an increase in temperature to 250 K. The Seebeck coefficient of the systems studied decreases as the strontium concentration and temperature increase. It has been shown that, for an adequate explanation of this behavior, proper allowance must be made for the splitting of the 3d levels, as well as for the charge disproportionation of the cobalt ions.

The impact of titanium dioxide (anatase) nanocrystals on growth process, optical and structural properties of KDP single crystal was studied. As-grown crystals were characterized by High Resolution Three-crystal X-ray Diffractometer, optical diagnostics of elastic scattering, cone-shaped interference method, and spatial profile analysis method. In the composite system KDP:TiO2 the effect of giant nonlinear optical response of anatase nanoparticles was revealed, in particular in the intensity range up to 20 MW/cm2 the change of sign of the nonlinear refraction index was found. These results can be explained by the resonance excitation of defective states on TiO2 nanoparticle surface.

AFM topography, TEM data, spectra of radiative annihilation of excitons in tetrahedral nano carbon quantum dots (QDs) and quantum rings (QRs) were studied in detail. Anti-Stokes exciton emission (ASEE) spectra in 6.3–4.7 eV energy interval at 4.2–200 K were induced via cascade Urbach tail states transitions under femtosecond laser radiation (λ=266 nm) pumping. Near diamond in composition nano carbon layers (nt-C) on cleaved KCl and polished Si substrates with high density of self-organized surface QDs, isolated, aggregated QRs and fractal bulk networks were grown using carbon ion beam of low energy and fluence. Regular networks of QDs 3–20 nm in diameter less than 1 nm in height and up to 3×1011 cm-2density were obtained. In ASEE spectra fine–structured via 5–6 meV narrow and week 6.0596 eV, 6.0557 eV and 6.0032 eV lines have been resolved at low level of excitation. The strong, fine-structured via 3.0–4.5 meV lines and bands above and below the energy of indirect exciton transition in diamond have been found in two types of nt-C layers as well. The parameter dependences of lines and bands upon the level of laser pumping were studied. We suppose that above mentioned components of ASEE spectra are originated from radiative annihilation of excitons in surface and bulk QDs and ring-like quantum networks. At strong excitation level fine-structured with 3.5–4.0 meV energy period new 4.8394 eV and 4.7925 eV exciton lines were induced and dominated in emission spectra. These lines are result of exciton annihilation in bulk quantum confined fractal features. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A laboratory setup for direct ion deposition intended for obtaining silicon carbide films under the conditions of the condensation of carbon and silicon ions with energies of ≥100 eV is described. The setup contains an original vacuum-arc source of carbon-silicon plasma with an extended cathode and an inhomogeneous magnetic field. The design features of the plasma source, the main technological characteristics of the setup, and the regimes of deposition of nanocrystalline silicon carbide films are presented.

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.

Search for neutrino-less double beta decay of 100Mo is proposed using active method with Ca 100MoO4 scintillation crystals which show the brightest scintillation light among variety of inorganic scintillation materials containing Mo. Study of X-ray luminescence and scintillation properties such as energy response, number of photoelectrons/keV, absolute light yield, decay time, pulse shape discrimination and radioactive contamination of CaMoO4 crystals grown by the Czochralski method with different conditions are presented. Further R&D of resolution optimization, crystal quality improvement and background reduction are underway. Significant improvement of sensitivity to neutrino-less double beta decay can be achieved by using 10 Mo enriched Ca 100MoO4 crystals with good energy resolution and low background. Further reduction of background induced by 48 Ca two neutrino double beta decay can be achieved by using 48Ca depletion. We are planning to install several kilograms of Ca 100MoO4 crystals depleted in 48Ca at underground laboratory for the neutrino-less double beta decay experiment in the near future.

The laser properties of Bridgman method grown active crystals Cr2+:ZnMgSe and Fe2+:ZnSe were investigated at room temperature from the point of view of laser parameters. Cr2+:ZnMgSe crystal was pumped by the 1.66 μm wavelength radiation of pulsed Er3+:YAP laser. The maximum reached energy and slope efficiency with respect to absorbed pump energy was 4 mJ and 15%, respectively. The Cr2+:ZnMgSe laser oscillation spectrum was about 90 nm wide and centered at 2.47 μm. With the CaF2 prism placed inside the laser resonator the tuning within 2.3 – 2.6 μm range was demonstrated. The pumping of Fe2+:ZnSe crystal was made by Q-switched Er:YAG laser radiation with the wavelength 2.94 μm. The measured maximum output Fe2+:ZnSe laser energy was 0.58 mJ with the generated wavelengths 4.3 – 4.6 μm and with a slope efficiency in respect to absorbed energy of 38%. The study demonstrates quite promising perspectives of the Bridgman-technique-grown Cr2+:ZnMgSe and Fe2+:ZnSe crystals for development of the efficient at room-temperature working mid-IR tunable laser sources.

The effect of irradiation with electrons on the optical and electrical properties of the nanocrystalline rhombohedral 21R-SiC and 27R-SiC films is studied. The cycles of irradiation of nanocrystalline SiC films on sapphire substrates with electrons with the energy 10 MeV are conducted in the range of fluences from 5 × 1014 to 9 × 1019 cm−2. It is established that, at the irradiation doses above 1019 cm−2, the optical absorption of the films at the photon energies E > Eg becomes less efficient than the optical absorption of unirradiated films. It is established that the Urbach energy as a function of the irradiation dose exhibits a minimum at the dose ∼1017 cm−2 for the 21R-SiC films and ∼5 × 1017 cm−2 for the 27R-SiC films, suggesting that radiation induces some ordering in the films. As the dose is increased from 5 × 1017 up to 9 × 1019 cm−2, an increase in the Urbach energy and a decrease in the optical band gap are observed. The effect is attributed to an increase in the concentration of radiation defects in the films.

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.

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.

We have examined conditions for the crystal growth of KDP doped with rare-earth (Ce, Sm, Gd, Yb) complexes with alizarin complexone. The complexes have different effects on KDP crystal growth and are selectively incorporated into the growth sectors of the crystals, which can be rationalized in terms of their structure and charge. In going from KDP solutions to crystals, the absorption bands of both the free ligand and its complexes with the rare-earth metals (482–510 nm) shift insignificantly. In contrast, the luminescence spectra of the complexes and ligand experience a bathochromic shift. The Stokes shift of the complexes in crystals is three to four times greater than that in solutions. The luminescence bands are centered at 598–625 nm.

Potassium dihydrogen phosphate crystals (KDP, KH 2 PO 4 ) doped with the organic xylenol orange (XO) dye are grown, the XO concentration in the crystal matrix is about 10 ppm. The spectral and luminescent properties of nominally pure, dye-doped and dye-doped/annealed at 150 °C crystals (KDP, KDP:XO and KDP:XO an ) were measured. The annealing temperature effect on the degree of dye protonation in the crystal matrix is established. Analysis of the IR-absorption spectra reveals a strong interaction between the incorporated dye molecules and the hydrogen subsystem of the matrix. The nonlinear optical (NLO) properties of KDP, KDP:XO and KDP:XO an crystals are studied within the self-action effect of picosecond laser pulses at 532 nm. The mechanism of photoinduced bleaching and the effects of laser beam self-focusing (in KDP) and self-defocusing (in KDP:XO and KDP:XO an ) are supposed to be due to resonance excitation of the subsystems of intrinsic defects and dye molecules, correspondingly. For KDP:XO an it is shown that thermal annealing of intrinsic crystal defects leads to domination of more effective NLO response of the subsystem of dye molecules that is correlated with photoluminescence data.

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.

PbF2-and BaF2-doped PbWO4 crystals have been grown by the Czochralski method. The scintillation characteristics of the grown crystals have been determined. It is shown that introduction of BaF2 leads to an increase in the light yield of PbWO4 crystals by 20%, while PbWO4:PbF2 crystals demonstrate a significant increase in radiation hardness.

Potassium dihydrophosphate single crystals were grown from aqueous solutions onto a point seed using temperature reduction method by doping with different molar values of urea. The characterization of the grown crystals was made by visible and Fourier transform infrared spectroscopy, Vicker's hardness studies, X-ray powder diffraction, non-linear optical and laser damage threshold measurements. By comparing these crystals with the ones grown from the pure solution, it is shown that 0.2–2.0 M of the urea additive enhances the laser damage threshold and the second harmonic efficiency more than by 25 and 20%, respectively. By means of the Bond method using a multipurpose three-crystal X-ray diffractometer it is shown that the presence of urea additive increases the crystal lattice parameter c of the grown crystals, whereas the lattice parameter a is by an order less sensitive to the changing urea concentration in the solution. The Vicker's hardness studies at room temperature carried out on (1 0 0) and (0 0 1) crystallographic planes show an increased hardness of the doped crystals (grown in the presence of urea additive) on the plane (0 0 1) in comparison with that of pure potassium dihydrophosphate crystal.

The features of doping of KDP crystals with cerium ions and organocerium complexes with alizarin complexon and arsenazo III have been investigated. It is established that “direct” doping by introducing cerium salts into the initial solution cannot be implemented. The effect of organometallic complexes of cerium on the crystal growth has been studied. Organocerium complexes predominantly enter the prismatic or pyramidal growth sectors. It is shown that the complex arsenazo III + Ce blocks the growth of the prismatic sector. Cerium-doped KDP crystals exhibit a photoluminescence band peaking at the wavelength λmax= 350 nm.

The method of direct deposition of carbon and silicon ions was used for preparation of nanocrystalline silicon carbide films. The deposition energy of carbon and silicon ions was 90 eV. The effect of substrate temperature in the range of 500–1150 °C on the structure of SiC films was studied by means of X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD). According to XPS data, the films contained heterobonded Si–C atoms and homobonded Si–Si and C–C atoms, the relation between which varied as the function of substrate temperature. The data of XRD showed a noticeable growth of a nanocrystalline phase of cubic silicon carbide in the films at a temperature of about 700 °C. The content of 3C–SiC nanocrystalline phase reached 80 at.% at 950 °C. There was an established change from cubic polytype to rhombohedral polytype of silicon carbide α-SiC–21R at a substrate temperature higher than 1000 °C. The size of SiC crystal grains depended on the substrate temperature and changed from 4–5 up to 8–10 nm over the range of 700–950 °C. Besides, silicon unbonded with carbon also crystallized in nanocrystalline form with similar sizes of crystal grains. A possible model of the change of the polytypic composition of SiC film under the conditions of direct ion deposition was discussed.

Spectral dependences of effective values of the real and imaginary parts of the low-frequency permittivity of the Cd1−xZnxTe crystals (x=0.12–0.16) with the Schottky barrier fabricated on the surface are measured. It is found that the boundary wavelengths of the characteristic portions of the measured dependences represented in the complex plane correspond to energies of photons, which cause the radical variations in the state of negatively charged and electrically neutral localized acceptor states. The variations in the energy spectrum of the localized states, which are determined by the magnitude and polarity of the electric bias applied to the Shottky barrier, are found.

Crystals of K 1 - x A x DP : Tl (0.1 wt%) were grown. Different fractions of potassium ions in the form of prism and pyramid morphology at x > 0.8 were found. The fluorescence emission (277–282 nm) and excitation (205–210 and 225–230 nm) spectra of mixed crystals doped with thallium were measured. The scintillation light output was determined under excitation by both α - and β -particles.

Compact broadly tunable Cr:ZnSe laser was constructed and described. Cr:ZnSe bulk crystal was grown by the Bridgman technique. In our best knowledge the bulk Cr:ZnSe prism was utilized as laser active media and simultaneously as an intra-cavity dispersive element for the first time. The maximal output pulse energy was 20 mJ. The generated radiation was tunable from 2000 up to 2750 nm. The repetition-rate was 1 Hz. The generated radiation beam spatial structure was close to TEM00.

Potassium dihydrogen phosphate (KDP) crystals doped with xylenol orange (XO) and methylthymol blue (MTB) are grown from aqueous solutions by the method of solvent evaporation at room temperature under the conditions of natural convection and by the method of temperature lowering. Studied is the influence of the mother solution acidity on the character of the crystal coloration. The color and coloration intensity of the grown crystals are shown to strongly depend on the solution's pH. It is revealed that the crystal habit changes in the presence of organic dyes. The optical transmission spectra and the luminescence spectra of KDP:XO solutions and of the grown crystals are measured. The effect of thermal treatment and UV-irradiation on the coloration stability of the crystals is studied. It is found that the laser damage threshold in the prismatic impurity rich colored sectors of KDP:XO is the same as that in the prismatic sectors of pure KDP crystals. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The aim of the presented work was to design and characterize bulk Fe:ZnSe and Fe:Zn(1-x)Mg(x)Se (Mg content x = 0.19) lasers coherently pumped by electro-optically Q-switched Er:YSGG laser. This laser generated pumping radiation at 2.79 μm with the maximum energy of 50 mJ in 80 ns long pulse with the repetition-rate of 1 Hz. The 25 mm long optical resonator of Fe:ZnSe or Fe:ZnMgSe lasers was formed by a plan dichroic pumping mirror and a concave output coupler (r = 200 mm) with reflectivity 88 % @ 4-5 μm. Both lasers were operated at room temperature. Measured maximum output energy/slope efficiency in respect to the absorbed energy was ~ 3.8 mJ/42 % for the Fe:ZnSe laser and ~ 0.48 mJ/10 % for the Fe:ZnMgSe laser. The generated output pulse duration was 150 – 200 ns in both cases and the output beam spatial profile was approximately gaussian. The Fe:ZnSe and Fe:ZnMgSe lasers output spectra line-width was ~ 200 nm (FWHM) and their maxima were centered at 4.45 μm and 4.8 μm, respectively. The results were compared to pumping the same crystals by a Q-switched Er:YAG laser in similar conditions.