The pulsed cathodoluminescence spectra of zinc selenide at room temperature were recorded: feedstock and materials required for the synthesis of optical ceramics. Samples of the cubic phase ZnSe with stoichiometric composition were also studied in the presence of additional phases (hexagonal ZnSe and ZnO). Three characteristic luminescence bands were detected for single-phase cubic zinc selenide. For the cubic ZnSe with stoichiometric composition one strong line of interband luminescence with a width of 12–14 nm is observed in the region of 470 nm; with an excess of selenium, an additional broad band appears at 647 nm, and with an increased impurity content and a small excess of zinc a single band is observed at 588 nm. In two-phase materials containing cubic and hexagonal ZnSe as the main or additional phase luminescence is not observed at room temperature. In the spectrum of cubic ZnSe with an additional hexagonal ZnO phase, a strong broad doublet band of hexagonal ZnO appears at 525–900 nm in addition to the interband luminescence line with a wavelength that decreases from 470 to 466 nm with increasing ZnO content. A rapid analysis of the quality of the ZnSe material can be carried out on the basis of the presence or absence of these pulsed cathodoluminescence bands.

Pulsed cathodoluminescence kinetics (PCL) of Fe:ZnSe ceramic samples, which were manufactured at the IEP UB RAS, was studied. The luminescence of divalent iron ions has a wide radiation band in the range of 3.6-4.4 μm at the 5 T 2 to 5 E transition [1]. This material is promising as an active medium for mid-infrared lasers and scintillation sensors.

The Ozerninsky ore cluster is a unique geological megastructure in terms of the concentration of rich and diverse mineralization. More than 20 deposits of lead, zinc, iron, copper, barite, and gold are concentrated here, including the Ozernoye polymetallic deposit, the largest in Russia in terms of the zinc reserve. Our studies have shown that many morphological features of the ores of this deposit, which most researchers assign to the hydrothermal-sedimentary type, are ambiguous; some signs of a metasomatic origin of the sulfide mineralization are observed. Along with lead-zinc deposits, complex gold-polymetallic, iron-oxide (hematite-magnetite), and copper-barite deposits are known within the Ozerninsky ore cluster, the origin of which remains debatable. Due to the wide distribution of exogenous gold deposits, there exists a need to assess the gold content of various types of the endogenous ore mineralization as potential sources of the precious metals. Despite the rather long period of studies of the Ozerninsky ore cluster (more than half a century), many questions related to ratios of the different mineralization types, the age, genesis of the ores, and geodynamic settings of formation of the deposits are still the subject of discussion. Solution of these issues requires more detailed geochronological and lithological-stratigraphic investigations conducted in combination with studying the mineral composition of the ores, their isotope-geochemical characteristics, and the physico-chemical formation conditions.

This paper reports on the synthesis of terbium sesquioxide (Tb2O3) nanoparticles via laser ablation of a solid target in a flowing 95 Ia3 symmetry as a result of firing in argon or vacuum at temperatures near 750 and 1050°C, respectively. Using temperature-dependent specific magnetization measurements, we determined their paramagnetic Curie temperature (θp = –11.8 K), Curie constant (C = 11.74 K emu/(mol Oe)), and effective magnetic moment (μeff = 9.69μB/Tb). These data suggest that antiferromagnetic exchange interaction between the terbium ions prevails and that the content of Tb4+ ions in the nanopowder is negligible. We have demonstrated the feasibility of producing transparent Tb2O3 ceramics by consolidating presintered nanoparticles via hot isostatic pressing for 2 h at a temperature of 1450°C and pressure of 200 MPa.

This paper presents the research of a new jewelry and ornamental stone-rayizite. Comprehensive studies of the mineralogical and chemical composition of rayisite were carried out. The main gemological characteristics and features of the nature of the color of this jewelry material are revealed.

The results of comparative investigations of the parameters of pulsed cathodoluminescence of crystals and ceramics excited by runaway electron beams with a duration of 10–12 ps and by electron beams with a duration of 2 ns generated in a vacuum diode are presented. It is shown that the luminescence spectrum and the decay kinetics of the bands coincide in both cases. When excited by a beam of runaway electrons, a lower luminescence intensity is observed. In certain cases, a delay in the appearance of luminescence relative to the onset of the electron-beam action is found. The mechanism for the appearance of a delay upon excitation by the beam of runaway electrons is associated with the process of luminescence rise.

This article discusses the general classification approaches and key features of different families of polymetallic deposits, with particular attention to the largest in Eurasia Ozernoe polymetallic deposit located in Western Transbaikalia and thoroughly explored 50 years ago. The main groups (or families) of polymetallic deposits in the English-language literature are identified by brief names: volcanogenic massive sulphide (VMS), sedimentary exhalative (SEDEX), and Mississippi Valley type (MVT). Within these three families of deposits, there are many additional types/subtypes, a large number of which are mostly due to the incompleteness and inconsistency of accumulated knowledge on the genesis of polymetallic deposits. Overall, all Pb–Zn(Ag,Cu) deposits—both those that are considered syngenetic, forming on and near the seafloor (VMS and SEDEX), and epigenetic low-temperature ones (MVT)—demonstrate a wide range of features that distinguish and bring together these families. This also applies to the types and subtypes of mineral deposits identified within them. One of the most complex objects for geological–genetic classification is the Ozernoe deposit studied by the authors, which, in terms of the nature of the host rocks, is intermediate between the end members of all three families: SEDEX, VMS and MVT. The deposit is localized in volcanic–carbonate–terrigenous rocks of the Cambrian Oldynda formation, but the age and stratigraphic affiliation of the ore-bearing series remain a matter of debate. The Ozernoe deposit is a combination of massive sulfide and siderite ore beds, ore breccia horizons, low-carbonate aleuropelite members, limestones, fine detrital tuffites, lavas, and tuffs. The sulfide bodies are confined to several stratigraphic levels, and the main productive unit thickness reaches 230 m. The thickness is comprised of 12 mineral lodes, a series of stratified ore bodies separated by gangue layers of sedimentary and volcaniclastic rocks. The primary ore minerals are pyrite, sphalerite, and galena, while the minor minerals include magnetite, chalcopyrite, marcasite, tetrahedrite, and arsenopyrite. There are two main theories regarding the origin of the ore: volcanogenic–sedimentary and hydrothermal–metasomatic. The hydrothermal–sedimentary theory remains the prevailing hypothesis, but there are many indications that epigenetic hydrothermal–metasomatic and dynamic metamorphic processes have contributed to the formation of the deposit. These include the appearance of sulfide–quartz and quartz–carbonate–sulfide veins and vein zones in fine-grained “layered” ores, with large crystalline sphalerite and galena; multiple signs of ore recrystallization, including the formation of pyrite porphyroblasts and arsenopyrite metacrystals; and the formation of solid pyrrhotite and pyrrhotite–magnetite ores with a lenticular-striped, gneissic structure. These observations suggest that different processes, both hydrothermal–sedimentary and metamorphogenetic–metasomatic, were involved in the formation of the Ozernoe deposit. In other words, primary hydrothermal–sedimentary ores were redeposited by late hydrothermal solutions. Nevertheless, many issues concerning the genesis of the Ozernoe deposit remain unresolved.

Сообщается о синтезе наноразмерных частиц полуторного оксида тербия (Tb 2 O 3 ) методом лазерной абляции твердой мишени в потоке двухкомпонентной сварочной смеси 95% Ar + 5% H 2 с использованием волоконного иттербиевого лазера со средней мощностью 300 Вт. Исследованы морфологические и структурные особенности полученного нанопорошка, его термическое поведение и магнитные свойства, а также динамика уплотнения в процессе нагрева до 1450°C в вакууме. Синтезированные частицы имели форму, близкую к сферической, средний размер 13 нм и моноклинную кристаллическую структуру, необратимое преобразование которой в кубическую структуру с симметрией \(Ia\overline 3 \) достигалось посредством обжига в аргоне или вакууме при температурах около 750 и 1050°C соответственно. С использованием измеренной температурной зависимости удельной намагниченности установлены значения парамагнитной температуры Кюри (θ p = −11.8 K), постоянной Кюри ( C = 11.74 К эме/(моль Э)) и эффективного магнитного момента (μ eff = 9.69 μ B /Tb), указывающие на преобладание антиферромагнитного обменного взаимодействия между ионами тербия и на предельно низкое содержание ионов Tb 4+ в нанопорошке. Показана возможность изготовления прозрачной керамики Tb 2 O 3 с помощью консолидации предспеченных наночастиц методом горячего изостатического прессования в течение 2 ч при температуре 1450°C и давлении 200 МПа.

The kinetics of pulsed cathodoluminescence of Nd3+ ions in single crystals, ceramics, and nanopowders of Nd3+ : Y3Al5O12 (Nd3+ : YAG) and Nd3+ : Y2O3 under excitation by a 2 ns electron beam with average electron energies of 130, 150, and 170 keV was studied. In this case, the luminescence of these substances occurs after the termination of the electron beam. In Nd3+ : YAG, there are optical transitions from the 2F25/2 level of the neodymium ion in the ultraviolet and visible regions of the spectrum, as well as from the 4F3/2 level in the near infrared region. In Nd3+ : Y2O3, there are not transitions from the 2F25/2 level of the neodymium ion, but infrared luminescence occurs from the 4F5/2 and 4F3/2 levels. The luminescence kinetics is characterized by rise and decay and it is described by the difference of two exponential functions. It is found that the characteristic luminescence decay times are the lifetimes of the 2F25/2, 4F5/2 and 4F3/2 emissive levels, and the rise time is determined by their pumping in recombination and relaxation processes. The rise mechanisms of pulsed cathodoluminescence are substantially different from the mechanisms of "phosphor ignition", which occur during ionization and excitation of the phosphor by an external source. Keywords: pulsed cathodoluminescence, neodymium ion, yttrium-aluminum garnet, yttria, kinetics, rise time, decay time.

Fabrication of optical ceramics based on solid solution of yttrium and gadolinium sesquioxides activated by Nd3+ ions was reported. Nanopowder of Nd0.08(Y0.496Gd0.496)2O3 synthesized by laser ablation method was used as raw material. It was determined that laser-ablated nanoparticles initially have monoclinic phase transformation of which into cubic phase is started at the temperature of 1100 °C and fully completed at 1300 °C. It was found that the best transparency of samples (79.9% at the wavelength of 1060 nm) and lowest content of scattering centers of 2.7 ppm are reached by vacuum sintering of nanopowder previously calcined at 1000 °C for 3 h. A blue-shift of Nd3+ emission bands in (Y,Gd)2O3 matrix with respect to Y2O3 was observed as a result of measuring of photoluminescence spectrum. Broadening of emission bands and their partial overlap was determined suggesting the alteration of local environment of neodymium which embeds into positions of yttrium as well as gadolinium.

The kinetics of pulsed cathodoluminescence of Nd3+ ions in Nd:YAG single crystals and ceramic samples was studied. In these substances, luminescence appears after the ending of exposure by an electron beam with a duration of 2 ns. Optical transitions are observed from the 2F2 5/2 level and manifest themselves in the ultraviolet and visible regions of the spectrum, and from the 4F 3/2 level – in the near infrared region. The kinetics of luminescence is characterized by a rise and a decay and is described by the difference between two exponential functions. It has been determined that the characteristic decay times of luminescence are the lifetimes of the 2F2 5/2 and 4F 3/2 radiative levels, and the time of a rise is determined by the pumping mechanism. Moreover, the pumping of the uppermost Stark component of the 2F2 5/2 level occurs in the process of linear recombination of the ionized neodymium ion with free electrons, and the 4F 3/2 level is due to nonradiative transitions from the upper levels.

The kinetics of pulsed cathodoluminescence of Nd3+ ions in single crystals, ceramics, and nanopowders of Nd3+:Y3Al5O12 (Nd3+:YAG) and Nd3+:Y2O3 under excitation by a 2 ns electron beam with average electron energies of 130, 150, and 170 keV was studied. In this case, the luminescence of these substances occurs after the termination of the electron beam. In Nd3+:YAG, there are optical transitions from the 2F25/2 level of the neodymium ion in the ultraviolet and visible regions of the spectrum, as well as from the 4F3/2 level in the near infrared region. In Nd3+:Y2O3, there are not transitions from the 2F25/2 level of the neodymium ion, but infrared luminescence occurs from the 4F5/2 and 4F3/2 levels. The luminescence kinetics is characterized by rise and decay and it is described by the difference of two exponential functions. It is found that the characteristic luminescence decay times are the lifetimes of the 2F25/2, 4F5/2 and 4F3/2 emissive levels, and the rise time is determined by their pumping in recombination and relaxation processes. The rise mechanisms of pulsed cathodoluminescence are substantially different from the mechanisms of "phosphor ignition", which occur during ionization and excitation of the phosphor by an external source.

The pulsed cathodoluminescence of Nd3+ ions in Nd:YAG single crystals and ceramics is studied. These materials luminesce after action of an electron beam pulse with a duration of 2 ns. Optical transitions occur from the 2F25/2 level and manifest themselves in the ultraviolet and visible spectral regions, while transitions from the 4F3/2 level are observed in the near IR region. The luminescence kinetics is characterized by rise and decay and is described by a difference between two exponential functions. It is found that the characteristic luminescence decay times are the lifetimes of the radiative 2F25/2 and 4F3/2 levels, while the rise time is determined by the mechanism of their population. The population of the upper Stark component of the 2F25/2 level occurs as a result of linear recombination of ionized neodymium ions with free electrons, while the 4F3/2 level is populated due to nonradiative transitions from the upper levels.

Background. The Novo-Uchaly copper-zinc VMS deposit in the Southern Urals (54°10΄54˝N and 59°20΄45˝E) is represented by a steeply dipping lens of Eifelian volcanics (rhyodacites and basalts), which are crumpled into a strongly compressed anticlinal fold. The ore deposit is blind and localised at the convergence of felsic (bottom) and mafic (top) rocks. The deposit is located at depths of 550 m (in the northern part) and 1050 m (in the southern part). The deposit thickness reaches 186 m. The length along the strike and along the dip equals 1250 m and 900 m, respectively. The ore body is intruded by gabbro-diorite and gabbro-diabase dikes. The main ore minerals are pyrite, sphalerite and chalcopyrite, as well as non-metallic minerals, such as quartz, barite and calcite. Unlike most of the Ural VMS deposits, this deposit is the zinc subtype (Zn >> Cu). The ores are predominantly massive and solid sulphide, being banded or brecciated in some parts. The main elements extracted are copper, zinc and sulphur, but gold, silver, cadmium, indium, cobalt, nickel, selenium and tellurium are also obtained.Aim. To clarify the morphology of the ore deposit, to study the ore mineral composition of the upper horizons of its northern part and to determine the underlying reasons for the complex lenticular structure of the sulphide reserve.Materials and methods. In the period 2017—2019, employees of the Institute of Ore Deposits, Petrography, Mineralogy and Biochemistry of the Russian Academy of Sciences (IGEM RAS) together with geologists of the Uchaly Mining and Processing Plant carried out a geological and mineralogical mapping of the deposit in the course of exploration works.Results. The ore contours and mineral composition of the northern part of the ore body were significantly clarified. A series of dikes of variable morphology was identified. A comparison was made of the results with current theories about the structure of the ore deposit. Detailed geological sections were determined and illustrate the complex lenticular structure of the ore deposit complicated by pinch and swell areas. The deposit was formed by processes of dynamic metamorphism.Conclusion. The geological and mineralogical structure of the deposit determined in the study enabled us to propose a schematic reconstruction of the conditions leading to the formation of its folded structure. The findings will help to re-assess the reserves and improve the system of operational exploration and delineation.

The possibility of developing a luminescence technique for phase composition analysis is demonstrated via the example of bi-phase yttria nanopowders doped with neodymium ions. The deviation from X-ray diffraction reference values is ±2%. It is found that the results depend on the inhomogeneity of the crystalline phase distribution within a sample’s bulk, rather than on the luminescence scattering by powder nanoparticles. A luminescence coefficient that determines the phase inhomogeneity in nanopowders is introduced.

This work investigates the characteristics of the gas discharge system used to create an atmospheric pressure plasma flow. The plasma jet design with a cylindrical graphite cathode and an anode rod located on the axis of the system allows to realize regularly reproducible spark breakdowns mode with a frequency similar to 5 kHz and a duration similar to 40 mu s. The device generates a cold atmospheric plasma flame with 1 cm in diameter in the flow of various plasma forming gases including nitrogen and air at about 100 mA average discharge current. In the described construction the cathode spots of individual spark channels randomly move along the inner surface of the graphite electrode creating the secondary plasma stream time-average distributed throughout the whole exit aperture area after the decay of numerous filamentary discharge channels. The results of the spectral diagnostics of plasma in the discharge gap and in the stream coming out of the source are presented. Despite the low temperature of atoms and molecules in plasma stream the cathode spots operation with temperature of similar to 4000 degrees C at a graphite electrode inside a discharge system enables to saturate the plasma by CN-radicals and atomic carbon in the case of using nitrogen as the working gas.

The spectra of luminescence of plumes that occur near targets of Nd: Y 2 O 3 , YSZ, and Al 2 O 3 when they are irradiated by pulses of a ytterbium fiber laser with a wavelength of 1.07 μm, duration of 1450 μs, and intensity of 0.4 MW/cm 2 are studied. Craters with a diameter of 400 μm and a depth of 600 μm appeared under such exposure in the targets. It is shown that the bands of the cation’s radicals of the targets, the intensities of which are distributed according to a law close to Planck’s law, predominate in the spectra of the plumes. On this basis, the temperature of the plumes was determined. It was about 2200–2280 K at the surface of the target, which is below the boiling temperature of the target due to cooling of the vapor during the passage of the deep laser crater.

The work demonstrates the luminescent method of identifying the phase composition of Nd3+:Y2O3-Al2O3 system by building calibration curves using standard samples.