Nanofine rhomboid spatial dissipative structures (NRSDS) of hexagonal selenium were found and studied by means of transmission electron microscopy in amorphous Se films coated with nanofine layers of amorphous carbon, at a temperature of their thermo gradient treatment of 423 K. As a result, pictures were received of fan-shaped linear bending extinction contours on the electron-microscopic images of NRSDS. It was shown that in the above NRSDS take place continuous linear increase in the bend radius of the lattice along [001], due to continuous linear relaxation of the inhomogeneous elastic torsion of the lattice around [001]. The continuous linear relaxation of the elastic rotational curvature of the lattice around [001] in NRSDS of hexagonal selenium with inhomogeneous elastic rotational curvature of the lattice covers the entire nanofine rhomboid spatial dissipative structures, and not its part, as is the case with the formation of interblock boundaries in the nanofine rhomboid spatial dissipative structures.

The nanofine spatial dissipative structures (NSDS) were characterized by transmission electron microscopy and electron diffraction. The NSDS obtained by thermogradiently processing an amorphous selenium film by unilateral heating of its lower surface at T = 413 K preliminarily. The results indicate that the NSDS of hexagonal selenium obtained in an amorphous film possess an azimuthal curvature of the lattice and a nonlinear fan-shaped system of flexural contours on their electron microscopic image. The lattice of the above NSDS undergoes elastic – plastic rotational curvature around three mutually perpendicular directions. The lattice rotation angles of hexagonal selenium NSDS reach: around [001], – 25°, around the direction perpendicular [001] and lying in the plane of the amorphous film – 32°, around the direction perpendicular to the first two ones and not lying in the plane of the amorphous film - azimuthal curvature of the lattice, – 35°. Thus, as a result of electron-microscopic and microdiffraction studies, it was found that NSDS of hexagonal selenium with azimuthal curvature of the lattice, causing the curvature of its habitus, are in a nonequilibrium state.

The paper studies the influence of the synthesis technology on the luminescent and optical characteristics of transparent Ce doped yttrium aluminum garnet ( YAG ) ceramics synthesized in two ways. The transparency of samples with a size of Ø10×2 mm reaches 60 to 81 % in the 500-900 nm wavelength range. The effect of intermediate synthesis steps on the optical characteristics and final concentration of the Ce3+ activator in the YAG ceramic has been described and discussed

In this paper, studies of the luminescence properties of nanocrystalline BaF2 samples synthesized by laser ablation and pulse electron beam evaporation method are presented. The measurements of X-ray excited luminescence (XEL) showed the dependence between luminescence intensity and the shape of the spectrum on the morphology and particle size. Also, studies of X-ray excited luminescence, decay curves and optical transmittance for nanocomposite materials containing BaF2 nanopowder are presented. Barium fluoride nanopowder, obtained by pulsed electron beam evaporation method is characterized by a lower intensity than the initial microcrystalline powder, but at the same time, XEL spectrum of the nanocomposite material with this nanocrystalline filler is more intense, then that for nanocomposite material with initial powder.

The X-ray luminescence (XRL) properties of gamma-AlON (gamma-Al5O6N), beta-SiAlON (Si6-nAlnOnN8-n, where n = 2 and 3) and Ca-alpha-SiAlON (Cam/2Si12-(m+n)Alm+nOnN16-n) oxynitride samples doped by Eu2+ were investigated. The strong correlation of luminescence spectra parameters of Eu2+ luminescence centers in dependence of oxynitride samples composition is observed. With fitting procedure the composition of XRL spectra with complex profile of investigated oxynitride samples of gamma-AlON, beta-SiAlON and Ca-alpha-SiAlON was identified and discussed.

The symmetry of direct and reciprocal lattices and the symmetry of bend contours present in the electron microscopy images of nanothin crystals with elastic rotational distortion of the lattice are examined using the example of nanothin selenium crystals.

In this paper, we report on the dependence of the luminescent and the optical properties on the synthesis conditions of the transparent 0.1 at.% Ce:YAG and 1 at.% Ce:YAG ceramics. The ceramics were produced from the nanopowders with a diameter of about 10–15 nm by means of the laser method. The fundamental difference between the two described methods is in the synthesis of the main phase YAG: directly during the vacuum sintering (1 – the first method) and before the vacuum sintering (2 – the second method). For this purpose, the transparent samples (Ø10×2 mm) with the optical transmittance ranging from 58 to 82% at the wavelength of 600 nm were obtained. The first method was proven to be the most preferable in terms of the exact dosage of the dopant which gives the samples the best scintillation characteristics. In a point of fact atom of cerium can potentially leave the material at any or at a certain stage of the ceramics synthesis, reducing the total concentration of Ce3+ in YAG.

By analyzing the patterns of flexural extinction contours present on the electron-microscopic images of nanothin (~80 nm) spatial dissipative structures (SDSs) of hexagonal selenium, i.e., nanothin crystals with elastic rotational curvature of the lattice around [001], the processes of formation of torn interblock boundaries in these structures are investigated. The effect of changing the disorientation-vector sign along the torn interblock torsion boundaries is observed. A model of formation of interblock torsion boundaries is developed for nanothin selenium SDSs, the lattice of which undergoes an elastic rotational curvature around [001].

A concept of data transmission within downhole telemetry systems in oilfield industry through power lines is presented. Based on this concept, MATLAB/Simulink models simulating communication lines in downhole telemetry systems are built, which can be used as prototypes for development of real systems. The most appropriate signal modulation methods for data transmission in downhole telemetry systems are suggested and discussed. The influence of high-voltage interference on signal transmission through power line from downhole unit to ground based unit is simulated. Usage of error-correcting coding methods for data transmission such as Hamming code, Reed-Solomon code, BCH code is suggested, and its efficiency is demonstrated.

In this paper, studies of the effect of morphology and particle size of BaF2 nanopowders obtained by laser ablation method and by pulsed electron beam evaporation method on luminescent properties are presented. SEM-images of the morphology of all samples are presented. In the X-ray excited luminescence spectra of nanopowders, a redistribution of the relative intensity is observed between the self-trapped exciton and core-valence bands. This may be due to a smaller influence of particle size on the mechanism of formation of the cross-luminescence band. The change in the shape of the self-trapped exciton spectrum is also observed for nanosized samples. This effect can be associated with the possibility of the formation of certain STE configurations inside a nanoscale crystal due to the different relative position of the F and H centers parts with respect to each other.

For investigation of more optimal characteristics for CaF2 additives for nanocomposite scintillator the dependences of synthesis method and annealing temperature on the X-ray luminescence and decay time for calcium fluoride were studied. The measurements of luminescence properties and luminescence decay parameters are revealed slow and fast components at emission band at 3.4 eV which is due to different self-trapped exciton (STE) states. The complex dependency of redistribution of the luminescence intensity and decay time for several components of X-ray excited luminescence spectra for CaF2 powders in depending on annealing temperature are observed.

Thermostimulated luminescence (TSL) of Al5O6N:Ce3+ and Al5O6N:Eu2+ with various dopant concentration has been investigated. Low-temperature TSL peaks in the range 300-500 K is observed. TSL curves approximated by sum of calculated curves with general-order kinetics. TSL intensity of samples with optimal dopant concentration (0.1 and 0.4 at. % for Ce3+ and Eu2+ respectively) is comparable with one of anion-defective corundum radiation detectors (TLD-500).

The thermally stimulated luminescence (TSL) and exoemission (TSE) in Li and Cu doped NaF and LiF single crystals irradiated with electron high energy electron beams of (10 MeV, doses 0.75 and 2 MGy) have been investigated. The results obtained reveal important properties that suggest that the crystals have a sufficient radiation stability and sensitivity for high energy electron beams and are promising for application as high-dose detectors of electron radiation.

Highly transparent YAG:Ce ceramics (transmission of 72-82% for 2-mm-thick samples in 550-900 nm wavelength range) were fabricated by solid-state reactive sintering using a mixture of Ce2xY2-2xO3 (x = 0.001, 0.01, 0.03, and 0.05) and Al2O3 nanopowders synthesized by laser ablation with an additional round of pre-calcining before compaction. The synthesized YAG:Ce ceramic materials showed intense luminescence with a maximum at 525-545 nm. The measured absolute light yields of the synthesized YAG:Ce ceramics were 18-21 photon/MeV for 1-5 at.% Ce and 5 photon/MeV for 0.1 at.% Ce. The energy resolutions of the fabricated thin ceramic samples (2 mm) under 662 keV gamma ray were measured to be 10-15%. The decay curves of scintillations consisted of two components with the decay times depending on the Ce3+ concentration. The sample doped with 5 at.% of Ce exhibited the main fast component with 26 ns decay time. The measured data was compared to that of YAG:Ce and well-known CsI:T1 single crystal scintillators. The influence of dopant concentration on the optical, luminescence and scintillation properties was discussed. (C) 2016 Elsevier B.V. All rights reserved.

X-ray luminescence (XRL) and pulsed cathodoluminescence (PCL) spectra of Eu2+-doped aluminum oxynitride Al5O6N (prepared using the standard sol-gel technique) have been investigated. The radioluminescence spectra, concentration dependences of light yield and time parameters of luminescence process have been measured and discussed. Some peculiarities of luminescence spectra as well as the possible excitation mechanism of AL(5)O(6)N with Eu2+ dopants are discussed too.

Micro- and spongiform nanocrystalline Zn2V2O7 compounds were synthesized by hydrothermal and solid-state reaction techniques, and their morphological features were investigated by scanning electron microscopy (SEM). The grain size ranges of the produced powders were 3-15, 0.5-2 mu m, and 50-500 nm. The luminescence spectra of these compounds were measured under pulse cathode beam and photoexcitation (200-400 nm). The luminescence decay properties of Zn2V2O7 were studied.It is found that the intensity, maximum position of luminescence spectra and luminescence decay time of Zn2V2O7 samples depend considerably on the grain size of the synthesized powders. The processes of energy relaxation in Zn2V2O7 and the observed size effect on the luminescence properties are also discussed. (C) 2016 Elsevier Ltd. All rights reserved.

The solid solutions Sr2Gd6.8Eu1.2Si6(1−x)P6xO26−δ (where x=0–0.15 and δ is oxygen nonstoichiometry) were synthesized. The structural properties of the crystal lattice of the solid solutions and the peculiarities of Eu3+ and P5+ dopants substitution for matrix ions have been considered. The photo-, X-ray and pulsed cathode luminescence properties have been studied. It has been found that substitution of (SiO4)4− by (PO4)3− tetrahedron in Eu3+-doped oxyapatites does not bring significant changes to bands structure Eu3+ in luminescence spectra under different excitation (UV, X-ray, pulse cathode beam). However, the increase of P5+ concentration in Sr2Gd6.8Eu1.2Si6(1−x)P6xO26–δ compounds leads to a decrease of integral intensity of Eu3+ luminescence bands due to local environment symmetry modifications and covalency degree changes. Two nonequivalent optical Eu3+ centers have been found. These compounds are of interest for efficient X-ray phosphors, display devices and LED engineering material creation.

Present work is dedicated to investigation of radiation optical properties of SiO2:Ge glass fibers produced by Fujikura and Corning Glass. Distribution of Ge dopant characteristics in core and cladding of quartz fibers have been determined. Ge dopant rings shaped luminescence in optical fibers has been observed. New method of determination the Ge dopant distribution in core and cladding cross sectional profile of silica glass fibers is presented. The thermoluminescence and light storage processes in fibers affected by x-ray radiation have been investigated. The photoluminescence investigations shows that there are two bands of luminescence with 400 nm and 550 nm maxima, which appear in different temperature stimulation conditions. Obtained results are discussed.

Preliminary investigations of thermoluminescent and thermoexoelectronic properties of transparent microstructured YAG:Nd and YAG:Yb ceramics are performed. Five peaks of thermostimulated luminescence are found for YAG:Nd in the VUV and UV ranges. Four and six peaks of thermostimulated exoemission are found for YAG:Yb and YAG:Nd, respectively. The parameters of carrier traps are calculated.