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We report an experimental study concerned with the synthesis and luminescence properties of Al5O6N aluminum oxynitride doped with Tb3+ in the concentration range 0.025–0.5 at %. All of the samples, prepared by firing appropriate mixtures in a nitrogen atmosphere at 1600°C, consisted predominantly of phase-pure γ-ALON (Al5O6N), with small amounts of impurity phases: Al7O3N5 aluminum oxynitride and Tb3Al5O12 terbium aluminate. Their pulsed cathodoluminescence and photoluminescence spectra contain emission bands typical of Tb3+ ions. The concentration threshold for luminescence quenching corresponds to a Tb3+ concentration at a level of 0.4 at %. A Tb3+ cross relaxation effect found in Al5O6N:Tb3+ is discussed and photoluminescence spectra are shown to be inhomogeneous at low Tb3+ concentrations in Al5O6N.

Polycrystalline Al5O6N samples have been prepared by sol–gel synthesis followed by carbothermal reduction and nitridation. X-ray luminescence (XRL) spectra and thermoluminescence (TL) curves of Ce3+- and Eu2+-doped aluminum oxynitride have been measured in the temperature range 5–380 K and analyzed. Working TL peaks have been detected in the range 150–250 K for the Al5O6N:Ce3+ sample and in the range 140–200 K for the Al5O6N:Eu2+ samples. There are also lower temperature peaks: in the ranges 10–60 and 20–100 K. The XRL spectra of the samples have been measured at temperatures of 8 (for the first time) and 300 K.

Herein we report the synthesis of aluminum oxynitride (Al5O6N) doped with Eu2+ and Ce3+ and examine the effects of the dopant concentration and the nature of the rare-earth-containing precursor (europium and cerium oxides, Eu(acac)3, and Ce(acac)3) on its properties. At dopant concentrations above the solubility limit of rare-earth aluminates (EuAl12O19 and CeAl11O18) in aluminum oxynitride, we observed the formation of aluminum nitride and aluminum oxide (α-Al2O3) as individual phases. The concentration of the latter phase was higher when the rare-earth oxides were used. The emission intensity in the cathodoluminescence spectra of the samples was shown to have a maximum at Eu2+ and Ce3+ concentrations from 0.1 to 0.5 at %. Concentration quenching of luminescence was observed.

The X-ray luminescence (XRL) properties of γ-AlON (γ-Al5O6N), β-SiAlON (Si6–nAlnOnN8–n, where n = 2 and 3) and Ca-α-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 γ-AlON, β-SiAlON and Ca-α-SiAlON was identified and discussed.

Four rubidium and cesium vanadates, with the compositions Rb5V3O10, Rb3V5O14, Cs5V3O10, and Cs2V4O11, have been synthesized and identified, and their thermal stability ranges have been determined. Their spectroscopic properties and luminescence kinetics have been studied: we have measured their X-ray luminescence spectra at room temperature and liquid-nitrogen temperature, photoluminescence spectra, and photoluminescence excitation spectra. The spectra are compared to those of RbVO3 and CsVO3—phosphors that have optimal properties among the alkali metal vanadates.

We have developed processes for the synthesis of the Rb 2Zn(VO3)4 and Cs2Zn(VO 3)4 tetrametavanadates. Rb2Zn(VO 3)4 has been prepared by solid-state reaction (350 C) between presynthesized RbVO3 and ZnV2O6 powders, and Cs2Zn(VO3)4 has been prepared by the Pechini method (sol-gel process). Both metavanadates crystallize in monoclinic symmetry (sp. gr. P21/m). Thermochemical characterization results demonstrate that the vanadates undergo complex transformations during heating to 450 C and subsequent cooling. As a result, the materials are in a nonequilibrium state at room temperature and consist of both the parent double metavanadates and their peritectic decomposition products. We believe that the formation of the structure of the M2Zn(VO3)4 compounds from their melts is a kinetically hindered process. These compounds are structurally stable only at temperatures below 369 (Rb2Zn(VO 3)4) or 420 C (Cs2Zn(VO3) 4). We have measured for the first time the diffuse reflectance and photoluminescence excitation spectra of the two tetrametavanadates in their emission range and their photoluminescence spectra at various excitation wavelengths and determined their chromaticity coordinates. Their X-ray luminescence and scintillation decay characteristics have been determined for the first time under pulsed electron beam excitation. The electron excitation dissipation processes in the cesium and rubidium compounds are shown to be similar. We discuss the origin of the emission bands in the mixed vanadates and their potential application areas. © 2013 Pleiades Publishing, Ltd.

Ce3+-doped borate crystal fibers of Li6Gd(BO 3)3 (LGBO) and Li6Y(BO3)3 (LYBO) compositions are grown by the micro-pulling down (μ-PD) method for potential application in developing new neutron detectors. The ternary equilibrium diagram of Li2O-Gd2O3-B 2O3 is drawn and the preparations of homogeneous mixed LGBO and LYBO powders and growth conditions for single crystal fibers are discussed. Absorption, excitation and X-ray luminescence spectra are investigated. Absolute light yield derived from energy spectra and kinetic decay curves measured under α- and γ-scintillations of Ce 3+-doped LGBO and LYBO single crystal fibers is provided. © 2012 Elsevier B.V. All rights reserved.

RbVO3, CsVO3, and Rb0.5Cs0.5VO3 have been synthesized by the Pechini process. The vanadates have an orthorhombic structure (sp. gr. Pbcm), melt congruently in the range 650–530°C, and undergo a reversible phase transition in the range 520–340°C. We have determined the onset temperatures and end points of the transformations at a temperature scan rate of 3°C/min and their enthalpies, and measured the photo-, roentgeno-, and cathodoluminescence and diffuse reflectance spectra of the vanadates. The luminescence spectra each are well fitted with three pseudo-Voigt functions. CsVO3 has the highest integrated emission intensity. The emission intensity of the Rb0.5Cs0.5VO3 solid solution is lower than that of the simple vanadates because of the optical absorption around its intrinsic luminescence band. This may be due to the presence of stable vacancy-type structural defects in Rb0.5Cs0.5VO3.

We have studied the compounds K2MgV2O7 and M2CaV2O7 with M = K, Rb, and Cs. These vanadates melt incongruently in the range 635–717°C. Cooling their decomposition products to room temperature leads to the formation of nonequilibrium phase assemblages characteristic of the corresponding oxide systems. The compounds offer broadband photo- and radioluminescence with an essentially white (to the human eye) emission spectrum. A model is proposed for luminescence centers in the vanadates, which involves the formation of defects in vanadium-oxygen groups, and an energy level diagram of the emission centers is constructed in the form of configuration curves in the harmonic oscillator approximation. The luminescent properties of these compounds suggest that they can be used as basic components of cathodo- and roentgenoluminescent screens and white-light-emitting diodes with improved color performance.

Rhombohedral hexametavanadates K4Sr(VO3)6, K4Ba(VO3)6, Rb4 Ba(VO3)6, and Cs4Ba(VO3)6 melt incongruently in the temperature range of 491 to 600°C. Cooling of peritectic melts yields mixtures of compounds typical of M2+O-M2+O-V2O5 systems, far from equilibrium and depending on the cooling kinetics. The vanadate Cs4Ba(VO3)6 undergoes reversible polymorphic transformation at 360°C. All compounds show broad-band luminescence with a maximum of the luminescence spectrum at 490–590 nm with three types of excitation. The vanadates K4Sr(VO3)6 and Rb4Ba(VO3)6 show the highest luminescence intensity at room temperature. The latter is also most efficient at liquid nitrogen temperatures. The luminescence spectra depend on the excitation of vanadates. Three hypotheses were put forward to interpret this finding. The nature of luminescence is attributed to the relaxation of electronic excitation in [VO4]3− structural tetrahedra present in the vanadates. The performance characteristics of luminophores were determined. These luminophores may be promising as X-ray luminescent screens, radioluminescence indicators, and light-emitting diode devices.

Optical absorption and luminescence of synthetic initial and neutron irradiated Gd2SiO5–Ce (0.5 mol.%) crystals was studied. Optical absorption spectra (1–6 eV) were measured using UV-Visible Helios Alpha spectrophotometer at T = 300 K . Time-resolved luminescence spectra (1.5–6 eV), luminescence excitation spectra (4–20 eV) and decay kinetics were recorded at SUPERLUMI station (DESY, Hamburg). Reactor neutron’s irradiation (fluence of 4⋅1018 cm−2) leads to the effective production of defects. There were not registered any new luminescence bands in the irradiated samples, but radiation defects take significant part in the processes of energy transfer to luminescence centers.

We have studied the thermal stability of five potassium strontium vanadates: KSr(VO3)3, K2Sr(VO3)4, K4Sr(VO3)6, K6Sr(VO3)8, and KSrVO4. The double orthovanadate undergoes a reversible polymorphic transformation at 1117°C and is stable up to 1500°C. The double metavanadates melt peritectically in the range 490–517°C to give Sr2V2O7 crystals and peritectic melt. Pulsed cathodoluminescence studies have shown that the potassium: strontium ratio in the vanadates and their crystal structure have little effect on their optical emission properties. The performance parameters of new vanadate-based phosphors have been determined.

The luminescence spectra of bulk and fiber sodium fluoride crystals activated with uranium ions have been analyzed. Luminescence of uranium centers at temperatures of 8.5 and 300 K is considered and the features of the luminescence spectra of these centers in crystals of different dimension are analyzed. The luminescence spectra are simulated with allowance for the spectral-line profiles. Possible models of uranium centers are considered.

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 AL5O6N with Eu2+ dopants are discussed too.

The spectroscopic properties of NaF:U bulk and fiber single crystals in the region 1.95–25 eV have been studied under the synchrotron radiation excitation at 8.5 K. Excitation and emission spectra have been recorded. In the emission spectra of NaF:U bulk and fiber crystals at least three new U 6+ sets of luminescence lines have been analyzed and discussed in addition to known ( Feofilov – Kaplyanskii ) ‘magnetic’ and ‘electric’ U 6+ sets of lines. Some peculiarities in luminescence spectra of NaF:U fiber crystals have been found and discussed.

The neutron induced defects in activated LiF and NaF single crystals have been investigated by studying the absorption and luminescence spectra. For LiF and NaF neutron irradiated crystals the creation of F, F2 and F3+ aggregate color centers have been analysed in comparison with F, F2 and F3+-center production in NaF crystals irradiated by ion and electron beams. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

New experimental data of the structure of a surface of fiber crystals (NaF, LiF and BGO) are presented in this paper. The explanation of observable features of a structure of their surface is offered. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The thermostimulated exoelectron emission (TSEE) of NaF:(U,Me) compounds after electron beam irradiation in the 300–800 K temperature range has been investigated. For NaF:(U,Me) bulk, fiber and nanocrystals several regular peaks of TSEE have been found. Additional effects with the sign of thermostimulated explosive electron emission have been found too. The nature of TSEE process is discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Emission and excitation spectra as well as decay curves of Er 3 + and Tm 3 + ions doped into SrF 2 crystals have been studied using time-resolved vacuum-ultraviolet spectroscopy under pulsed synchrotron radiation at 8 K. In emission spectrum for crystals doped with Er 3 + ions together with well-known emission caused by spin-forbidden 4 f 10 5 d → 4 f 11 transitions (decay constant in the microsecond range), a new fast emission band detected at 146.5 nm (decay constant is less than 0.6 ns) has been revealed. It was shown that excitation spectra of f–f and d–f emission bands for Er 3 + and Tm 3 + ions in SrF 2 have opposite behaviors in the spectral range corresponding to energy of their 4 f n - 1 5 d configurations. These peculiarities and energy transfer mechanisms were analyzed.

Spectroscopic studies of NaF:U,Cu bulk and fiber crystals have been performed in the near UV-vacuum UV (2–25 eV) region by the use of synchrotron radiation. Emission, excitation and reflectivity spectra have been recorded. The important role of Cu + ions in the uranium luminescence and energy transfer mechanisms was pointed out. Differences in luminescence properties of bulk crystals and crystalline fibers have been observed and analyzed.

This paper is a short review of some new scintillation materials, scintillation detectors and scintillation systems for registration of gamma-rays, X-rays, neutrons and neutrinos, which have been developed on the level of inventions and a new fundamental level in the Ural State Technical University-UPI (Ekaterinburg, Russia) and Laboratoire de Physico-Chimie des Materiaux Luminescents (Universite Lyon 1, France). The part of Russian patents for this area are presented: some most important new scintillation materials (on the base of lithium hydride, silicate compounds, compounds on the base of aluminates, compounds on the base of fluorides and oxyfluorides, compounds on the base of oxides and oxides crystals, glasses and transparent ceramics) and new scintillation devices (on the base of HgI 2 , on the base of LiKSO 4 , sandwich-detectors (organic–inorganic–glass–fiber materials), combine detectors, detectors with photodiodes registration and spectrum shifter, surface scintillation structures and screens, and fiber scintillation devices).

The results of investigation of particularity of radiation damage, modification of surface layers of (Li,Na)F single crystals, developing of scintillation heterostructures and scintillation screens with microns resolution on the base of (Li, Na)F single crystals are presented. The thin layered color center heterostructures and thin scintillation screens with high local resolution (35 μm) have been developed by using pulse electron and He + -ions beams.

The present work is devoted to investigations of the luminescence properties of aluminum-, beryllium- and silicon-containing complex wide gap oxides in energy range 2.5–32 eV at temperature 10–300 K using time-resolved VUV-spectroscopy and ionluminescence methods. It has been shown that all studied crystals possess intrinsic luminescence in the UV-region of spectrum. Phenomenon of electron excitations multiplication has been found in excitation spectra of intrinsic luminescence. The difference and typical features of photoluminescence and ionluminescence (luminescence excited by accelerated particle beam) are discussed.

A study of transient optical absorption of the ADP (NH4H2PO4) and KDP (KH2PO4) nonlinear crystals in the visible and UV spectral regions is reported. Measurements made by absorption optical spectroscopy with nanosecond-time resolution established that the transient optical absorption (TOA) of these crystals originates from optical transitions in the hole A and B radicals and the optical-density relaxation kinetics is rate-controlled by interdefect tunneling recombination, which involves these hole centers and the electronic H0 centers representing neutral hydrogen atoms. At 290 K, hole polarons and the H0 centers undergo thermally stimulated migration, which is not accompanied by carrier ejection into the conduction or valence band. The slow components of the TOA kinetics with characteristic times from a few tens of milliseconds to a few seconds can be assigned to diffusion-controlled annihilation of hydrogen vacancies associated with impurity or structural defects.

The paper presents the results of a study of radiation energy storage, radiation effects, and radiation induced changes of optical properties in crystals KH2PO4 (KDP), (NH4)H2PO4 (ADP), and crystals KDP doped with either deuterium (KDP : D) or Cr (KDP : Cr). Both the X-rays and H + (0.71 MeV ), He + (4.6 and 27 MeV ), N + (16 MeV ) ion beams were used for irradiation of the crystals studied. Optical absorption spectra of KDP were measured after irradiation with various H+ ion beam doses, and accumulation of the radiation-induced defects was estimated. Considerations of the radiation effects in these crystals under irradiation with the ion beams were made taking into account the results of Monte Carlo simulations using the TRIM computer codes. Using the experimental and theoretical results the paper discusses the similarities and differences of these crystals with respect to radiation hardness and the processes of radiation energy storage.

The time-resolved emission spectra (2–6 eV), reflection and luminescence excitation spectra (4.5–35 eV) as well as the kinetics of luminescence have been studied for single crystals of silicates A 2 SiO 5 –Ce (A=Y, Gd, Lu) and Sc 2 SiO 5 at 5.8 and 300 K using synchrotron radiation of X-ray (storage ring VEPP-3) or selective vacuum ultraviolet (storage ring DORIS) range. The spectral and decay parameters of the impurity and intrinsic luminescence are determined. The photon multiplication effect was found for all compounds for energy E >15 eV ( E >2.5 E g ). The role of electron-hole and exciton mechanisms of energy transfer in the silicates and their dependence on temperature are discussed.

Low-temperature photoluminescence (PL) of unactivated KDP crystals under selective synchrotron excitation is for the first time measured with subnanosecond time resolution. Time-resolved PL (2–6 eV) and PL excitation (4–35 eV) spectra, as well as PL kinetics, are measured at 7 K. From the acquired experimental data, luminescent bands related to intrinsic defects of the KDP lattice are identified; in particular, the long-wave band at 2.6 eV is assigned to L defects, and the band at 3.5–3.6 eV is attributed to D defects. An efficient energy transfer over the hydrogen sublattice is shown to take place in KDP at low temperatures. It results in the efficient excitation of L and D center photoluminescence in the fundamental absorption region, at electron transitions to the bottom levels of the conduction band, corresponding to the states of the hydrogen atom. The band gap E g is evaluated to be 8.0–8.8 eV.

Luminescence and excitation spectra of doped LiF and NaF crystals are studied by time-resolved optical and luminescent vacuum ultraviolet (VUV) spectroscopy (2–40 eV energy range, T=10–295 K) with the use of synchrotron radiation of the X-ray and the VUV ranges and pulsed electron beams. Spectral kinetic parameters of luminescence and energies of excited states of U6+ ions are determined. The dominant role of the electron-hole mechanism for energy transfer to impurity centers is established. The effect of multiplication of electronic excitations is clearly manifested for E > 25 eV in NaF:U, Cu crystals and determines their high scintillation yield (137% relative to Tl:CsI when detected in the current regime).

Electronic excitations and the processes of their radiative relaxation are studied in pure and Ce3+ ion-doped crystals of lanthanum beryllate excited by synchrotron radiation in the x-ray and VUV ranges by methods of optical and luminescent vacuum ultraviolet time-resolved spectroscopy. Manifestations of excitons of the valence band are absent in the reflection spectra. However, a fast (τ=1.7 ns) and a slow (microsecond range) channel corresponding to two possible types of self-trapped excitons (STE) are found in radiative relaxation of intrinsic electronic excitations at T=10 K. The slow channel corresponds to emission of STE formed through recombination, the fast channel corresponds to emission of relaxed metastable excitons from the STE state. In the energy region higher than 14 eV (E>2Eg), the effect of multiplication of electronic excitations due to generation of secondary electron-hole pairs resulting from inelastic scattering of both hot photoelectrons and hot photoholes is exhibited.

The energy transfer between the rare-earth ions in Y s SiO 5 Ce, Tb crystals has been investigated with the use of the methods of luminescence spectroscopy with subnanosecond time resolution and excitation by pulsed synchrotron radiation (SR). Effective nonradiative energy transfer between Ce 3+ and Tb 3+ -ions which is realized by the inductive resonance mechanism has been observed. The absolute constant of the energy transfer speed K t and the probability of transfer have been determined. A dependence of the energy transfer parameters on the SR-excitation density has been discovered and investigated. Increasing of the density of the SR-excitation by a factor of 10 results in the increase of K t from 4.8 × 10 8 up to 1.7 × 10 10 mol −1 s −1 .

Luminescence spectroscopy with subnanosecond time resolution is used to study features of nonequilibrium processes excited in several broad-zone dielectrics (mainly inorganic scintillators) by pulses of synchrotron radiation (SR). When excitation density exceeds a certain level, which is different for each material, there is an abrupt change in the kinetics of relaxation of the nonequilibrium states. This change is accompanied by nonuniform broadening or shortwave shifting of the luminescence spectrum and a drop in quantum light yield. The decay time for natural luminescence decreases by 1–3 orders, to nanoseconds, and is independent of temperature within the range 80–450 K. The build-up stage disappears in the kinetics of luminescence of Ce3+-centers and decay time is reduced by a factor of 2–4. Density effects are found to be independent of the conditions under which the material is exposed to SR. A model is proposed in which density effects are related to nonradiative energy transfer from the upper excited states of the luminescence centers to external quenching centers. The contribution of the space charge induced by SR is also examined.

Time-resolved spectra, decay kinetics, degree of polarization of the luminescence and transient optical absorption induced by irradiation of BeO with an electron, synchrotron and subsequent laser pulses have been studied. It is found that the two pairs of slowly and fastly decaying intrinsic luminescence bands at 6.7, 4.9 and 4.4 eV are associated with the two different types of the self-trapped excitons. The 1.7 eV transient optical absorption band and the ultra-violet absorption band at 3.6 eV are attributed to the electron and hole components of the self-trapped excitons, respectively. The transient optical absorption band with decay time of 6.5 ms is found to be due to the self-trapped holes. The models of self-trapped excitons and holes are discussed on the basis of the present experimental results.

We have developed a procedure for thermally stimulated synthesis of a cesium strontium metavanadate, Cs 2Sr(VO 3) 4:Mn 2+ (0.01, 0.50, 1.00, 5.00 at % Mn 2+), using MnO-containing starting mixtures. The EPR spectrum of the material containing 0.01 at % Mn 2+ shows a hyperfine structure due to the incorporation of a small amount of manganese into the diamagnetic double metavanadate host. The luminescent and optical properties of Cs 2Sr(VO 3) 4:Mn 2+ depend on manganese content. In contrast to higher doping levels, doping with 0.01 at % Mn 2+ increases the integrated emission intensity of the vanadate by 10% and improves its chromaticity characteristics (approaching them to those of white light). We assume that this is due to the reduction in the density of vacancy-type growth defects, such as oxygen vacancies. © Pleiades Publishing, Ltd., 2012.

Using solid-state reactions and a combination of carbothermal reduction-nitridation with sol- gel processing, we have synthesized a number of oxynitride phases: Eu 2+-doped Ca-sialons. We have mea- sured the pulsed cathodoluminescence spectra of the synthesized powders under pulsed electron beam exci- tation and determined their emission parameters, including temporal emission characteristics.. © Pleiades Publishing, Ltd., 2012.

In spite of the wide assortment, there is an acute lack of effective and sensitive scintillation blocks for detecting {beta}-radiation. One of the best single-crystal scintillators for detecting {beta}-radiation is CaF{sub 2}-Eu. The fundamental and applied characteristics of CaF{sub 2}-Eu-based scintillation detectors, including the temperature dependences of the light output and the energy resolution, as well as the state standard samples of light output based on them, are described. In elaborating this work new scintillation blocks for {beta}-detectors have been produced with sensitivity, determined from the minimum detectable activity of {beta}-preparations, three times higher than for CsI-Tl detectors. This is explained by the high light output of the scintillations and, most importantly, the much lower losses to reflection for the recorded {beta}-particles due to the low effective atomic number of CaF{sub 2}-Eu single crystals. This work was performed at the instrument plant of the Angarra Electrolysis Chemical Complex, taking into account the requirements of standards for scintillation detectors.

Azomethyne ylides generated from 3-alkylthio substituted 1-alkyl-5-aryl-1,2,4-triazinium salts 4a–c on treatment with triethylamine undergo 1,3-dipolar cycloaddition with dimethyl acetylenedicarboxylate to give pyrrolo[2,1-f][1,2,4]triazines, while 1-ethyl-5-phenyl-1,2,4-triazinium salts 1a,b bearing the CC bond in the side-chain 3-alkynylthio substituent react with acetylenes to undergo either intermolecular 1,3-dipolar cycloaddition or intramolecular inverse electron demand Diels–Alder reactions.

Kyropoulos method in an inert atmosphere; - Stockbarger method in an inert atmosphere. The doping with uranium impurity was accomplished in the course of crystal growth by adding UO2(NO3) 2 to the charge in amount of 0.01 mole %. Activation with the lead impurity was accomplished by several methods: doping in the course of crystal growth (PbF 2 in amount of 0.5 mole %); thermal diffusion in an inert atmosphere at a temperature close to the melting point of the matrix, for a period of 50 h; and by implanting lead ions (implantation performed in a DIANA-2 unit [7]). The surface density of the implanted lead ions was determined by backscattering of He + ions (1.65 MeV) in a cyclotron; the surface density proved to be (4.5-6.3)'i0 Is ions/cm 2 [7]. The depth of localization of lead ions in this case was no greater than 0.4 nm. Thermostimulated luminescence was studied in an automatic unit [9] operating in a loop with an Elektronika 0585 microcomputer. By means of a low-inertia nitrogen cryostat, the temperature was varied in the 80-550 K interval with a linear heating rate of 0.i or 0.3 K/ sec. Excitation was accomplished at 80 K by x-ray radiation from a BSV2:Cu tube (30 kV, i0 mA) with an exposure of 5 min. A vacuum better than 10 -4 Pa was obtained by pumping down with a nonoily medium. TSL was registered by means of an FEU-106 photomultiplier, and in the photon count mode an MDR-2 monochromator.

New high-temperature peaks of thermostimulated exoelectron emission (TSEE) from uranium-activated LiF and NaF Crystals were observed. TSEE parameters for various (Li,Na)-(U+Me) systems were determined.

The novel vanadium oxides Rb 2 CaV 2 O 7 and Cs 2 CaV 2 O 7 have been prepared by solid-state reaction and their crystal structures determined and refined using X-ray, neutron powder and electron diffraction data. Rb 2 CaV 2 O 7 and Cs 2 CaV 2 O 7 are isostructural, crystallizing in space group P 2 1 / n with unit cell parameters: a = 13.8780(1), b = 5.96394(5), c = 10.3376(1) A, β = 104.960(1)° and a = 14.0713(2), b = 6.0934(1), c = 10.5944(1) A, β = 104.608(1)°, respectively. Their crystal structures can be described as a framework of CaO 6 octahedra and V 2 O 7 pyrogroups with alkaline metals found in the tunnels formed. Photoluminescence (PL) and PL excitation spectra of the considered pyrovanadates have been studied in the vacuum ultraviolet (VUV) to visible light (Vis) range as well as their pulse cathode luminescence (PCL) spectra and the kinetic parameters of PCL. In the PL and the PCL spectra of both pyrovanadates recorded at T = 300 K a broad band with maxima at 2.2, 2.4 eV and two shoulders (bands) at 2.0 and 2.58 eV have been observed. At T = 10 K the band at 2.0 eV becomes the main band in the spectra. Two types of luminescence centers for each pyrovanadate, with very similar excitation bands at 3.75, 4.84, 6.2, 7.3 and 9.1 eV, have been found. The nature of the luminescence centers connected with the bands at 2.0, 2.2, 2.4 and 2.58 eV is discussed.

The physical properties of the family of cyclotetravanadates A(2)M(VO3)(4), where A=Na,Ag and M=Ca,Sr, have been studied by means of x-ray powder diffraction, neutron diffraction, electron diffract ...