Thermal and luminescent properties of M2Zn(VO3) 4 (M = Rb, Cs)

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

Time-Resolved Vacuum Ultraviolet Spectroscopy of Er3+ ions in the SrF2 Crystal

The photoluminescence and photoexcitation spectra as well as the luminescence decay kinetics of Er3+ ions in the visible ultraviolet and vacuum ultraviolet (VUV) regions have been studied by the method of low-temperature, time-resolved VUV-spectroscopy on excitation by synchrotron radiation. In the VUV spectral region of the luminescence of SrF2:1% Er3+, the 146.5-nm band with a time of decay of less than 0.6 nsec was revealed together with the well-known emission band at 164.3 nm (decay constant in the microsecond range). Its possible nature is discussed. The specific features of the formation of photoexcitation spectra of the f-f and f-d transitions in the Er3+ ion are considered. Competition between the processes of excitation of f-f and d-f luminescence has been revealed. It manifests itself in the inverse relationship of their photoexcitation spectra in a range of energies of incident photons that are close to the position of the 4fn-15d configuration levels. © 2005 Springer Science+Business Media, Inc.This work was carried out with the support of grants from the Russian Fundamental Research Foundation (05-02-16530), "Universities of Russia (UR 02.01.433), Ural Scientific Center Promising Materials" CRDF (EK-005-XI), and partially from BMBF (05KS8GMD/1)

Vacuum Ultraviolet Excitation of Rare-Earth ion Luminescence in Strontium Fluoride Crystals

The photoexcitation spectra (70-280 nm) of the Eu 3+, Tb 3+, Dy 3+, Er 3+, and Tm 3+ ion luminescence in strontium fluoride crystals are studied at 8 and 295 K by vacuum ultraviolet spectroscopy using synchrotron-radiation excitation. The processes of transfer of the excitation energy to the impurity centers as well as the relaxation mechanisms of the excited high-energy states of the rare-earth ions are analyzed. The bands corresponding to the interconfiguration 4f-5d transitions and the charge-transfer bands are identified in the photoexcitation luminescence spectra. ©2005 Springer Science+Business Media, Inc.The present work was supported in part by the Russian Foundation for Basic Research (Grant 05-02-16530), by the Program “Russian Universities” (Grant UR.02.01.433), by REC-005 (ЕК-005-XI), and BMBF (05KS8GMD/1)

Structure and luminescent properties of Cs2Sr(VO3)(4): Mn2+

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

RESEARCHING THE PROCESS OF HOLLOW PROFILE SETTING- PRESSING OF A COMPOSITE MATERIAL BASED ON METALLIC POWDERS

The paper presents the researching processes of hollow profile setting-pressing of a composite material based on "iron-copper" metallic powders and the improving of the quality by increas- ing the homogeneity of properties

INORGANIC SCINTILLATOR

FIELD: selective detection and displaying of heavy-density pulse electron beams in background α-, β-, γ radiation of nuclides, in particular, for electron beams generated by heavy-current amplifiers of electrons. SUBSTANCE: method involves usage of semiconductor crystals of HgI2 (red tetragonal modification) as inorganic scintillator.EFFECT: increased efficiency for detection of heavy-density electron beams, practical insensitivity to α-, β-, γ- radiation of nuclides.Использование: в качестве избирательного детектора для визуализации и эффективной регистрации импульсных пучков электронов высокой плотности на фоне α-, β-, γ - ядерных излучений радионуклидов в частности, для визуализации и регистрации электронных пучков, создаваемых сильноточными ускорителями электронов нано- и пикосекундного диапазона. Сущность изобретения: применение известных полупроводниковых кристаллов иодида ртути HgI2 (красной тетрагональной модификации) в качестве неорганического сцинтиллятора, обладающего высокой сцинтилляционной эффективностью Cотн при регистрации электронных пучков высокой плотности и практически не чувствительного как сцинтиллятор к ядерным α-, β-, γ- излучениям радионуклидов

METHOD OF COLORING NATURAL BERYL CRYSTALS AND ARTICLES MADE THEREFROM

FIELD: gem treatment. SUBSTANCE: method of coloring natural beryl crystals and articles (jeweler's insertions) to improve their color (simulation of emerald) involves irradiation of natural beryl crystals with ionizing radiation and heat treatment and is distinguished with that thermally treated crystals are submitted to a secondary irradiation, the both irradiation steps being effected with 6-8 MeV electron beam at fluency 10 15-2,5•1016 electrons per 1 sq.cm, whereas heat treatment is carried out via slow heating and cooling (2-2.5 deg./h) and exposure to 160-170 C for 1-2 h. EFFECT: improved quality of color.Предложен способ окрашивания кристаллов природного берилла и изделий из них /ювелирных вставок/ для улучшения качества их окраски - окрашивания под изумруд. Способ включает облучение кристаллов природного берилла ионизирующим и их термообработку и отличается тем, что термообработанные кристаллы подвергают вторичному облучению, причем первичное и вторичное облучение проводят электронным пучком с энергией 6-8 МэВ и флюенсом 1015 - 2,5 • 1016 электрон /см2/ при каждом облучении/, а термообработку ведут медленным нагревом и охлаждением /2-2,5 град/час/ с выдержкой при 160-170oC в течение 1-2 часов