Complex antimony pyrochlores Bi2.7M0.46Ni0.70Sb2O10+Δ (M = Zn, Mg) were synthesized from oxide precursors, using the solid-state reaction method. For each composition variant, the pyrochlore phase formation process was studied during solid-state synthesis in the range of 500–1050 °C. The influence of zinc and magnesium on the phase formation process was established. The interaction of oxide precursors occurs at a temperature of 600 °C and higher, resulting in the formation of bismuth stibate (Bi3SbO7) as a binary impurity phase. Oxide precursors, including bismuth(III) and antimony(III,V) oxides, are fixed in the samples up to 750 °C, at which point the intermediate cubic phase Bi3M2/3Sb7/3O11 (sp. gr. Pn-3, M = Zn, Ni) is formed in the zinc system. Interacting with transition element oxides, it is transformed into pyrochlore. An intermediate phase with the Bi4.66Ca1.09VO10.5 structure (sp. gr. Pnnm) was found in the magnesium system. The unit cell parameter of pyrochlore for two samples has a minimum value at 800 °C, which is associated with the onset of high-temperature synthesis of pyrochlore. The synthesis of phase-pure pyrochlores is confirmed by high-resolution Raman spectroscopy. The data interpretation showed that the cations in Ni/Zn pyrochlore are more likely to be incorporated into bismuth positions than in Ni/Mg pyrochlore. The nickel–magnesium pyrochlore is characterized by a low-porosity microstructure, with grain sizes of up to 3 μm, according to SEM data. Zinc oxide has a sintering effect on ceramics. Therefore, the grain size in ceramics is large and varies from 2 to 7 μm.

The results of experimental modeling of glassy carbon production from high-pressure supercritical fluid (SCF) in the C–O–H system at a temperature of 800°C and pressures of 500 – 1000 atm are presented. Acomprehensive characterization of the carbon material is presented, using the data from CHNS-O analysis, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), x-ray and electron diffraction, infrared and multiwavelength Raman spectroscopy (Raman). In light of the characteristics and outcomes of the comparison with industrial glassy carbon, the synthesized carbon material was classified as a glassy substance. The findings of the experimental studies provide evidence for potentially different mechanisms of formation and, consequently, polygenicity of the glassy state of carbon. The material obtained through a radically distinct production method (polycondensation) may possess distinctive surface and bulk properties.

At high PT parameters of cumulates of ultramafic–mafic intrusions and low oxygen fugacity (below QFM buffer), Pt in the form of a carbonyl complex is dissolved in a CO2-bearing fluid. The high solubility of Pt chloride in brines with NaCl, which is related to the formation of low-sulfide deposits of platinum group elements, is attained only at high oxygen fugacity (above the QFM buffer). It is suggested that native platinum at low oxygen fugacity in low-Н2О СО–СО2 (Н2О) fluid can also transit into a cation-soluble form due to the reaction of chloration. The experimental data are provided for the interaction of NaCl with magnetite and chromite (accessory minerals of ultramafic–mafic intrusions) at Р = 200 MPa, Т = 950°С, and fO2

Raman spectroscopic data of quenching phases in experiments on the dissolution of Pt in reduced carbonic fluid, containing about 30 mol

The preliminary results of experimental modeling of the impact process on a coal substance by short-pulse laser radiation are presented. During the experiments, extremely high temperatures and pressures were reached. Based on the analysis of the modified products of the target substance, coal melting was identified, followed by its cooling with subsequent solidification with the formation of glass-like carbon. The synthesis products may be of interest as novel carbon materials formed at ultrahigh pressures and temperatures, such as high-pressure carbon polymers and hollow fullerene-like structures. The results of experimental modeling can be used for comparison with naturally occurring materials in order to elucidate the mechanisms of the formation of natural high-pressure carbon substances from a non-graphite precursor.

At high PT parameters of the cumulates of ultramafic-mafic intrusions at low fO2 (below the QFM buffer), platinum dissolves in the fluid with CO as a carbonyl complex of the native metal. The high solubility of platinum as PtCl2 in brines with NaCl, which is associated with the formation of low-sulfide PGE deposits, is achieved at high oxygen fugacity (above the NNO buffer). It is assumed that at low oxygen fugacity in the low water CO–CO2 fluid, native Pt can also be converted into a cation-soluble form by chlorination. Experimental data (Р = 200 MPa, Т = 950oC, fO2 QFM and fluid CO–CO2) on the reaction of NaCl with magnetite and chromite, accessor minerals of mafic-ultramafic intrusions, with the formation of iron and chromium chlorides are presented. As shown by thermodynamic calculations, the equilibrium in the FeCl3–FeCl2 pair provides the high chlorine fugacity (fCl2). This fugacity is only 3–4 orders of magnitude lower than fCl2 in the Pt–PtCl2 equilibrium and 2.5–3 orders of magnitude higher than in the aqueous fluid 1 M HCl at the same P–T–fO2 parameters.

The new columbite-supergroup mineral dmitryvarlamovite, ideally Ti-2(Fe3+Nb)O-8, was discovered in weathered alkaline metasomatic assemblages formed after late Riphaean sedimentary carbonate rocks of the Verkhne-Shchugorskoe deposit, Middle Timan Mts., Russia. The associated minerals are columbite-(Fe), pyrochlore-group minerals, monazite-(Ce), xenotime-(Y), baryte, pyrite, drugmanite and plumbogummite. Dmitryvarlamovite occurs as isolated anhedral equant grains up to 0.5 mm across. The colour of dmitryvarlamovite is black, the streak is black and the lustre is submetallic. The new mineral is brittle, with the mean VHN hardness of 753 kg mm(-2) corresponding to the Mohs' hardness of 6. No cleavage is observed. The fracture is conchoidal. The calculated density is 4.891 g & sdot;cm(-3). In reflected light, dmitryvarlamovite is light grey; no pleochroism is observed. The reflectance values (R-min, % / R-max, % / lambda, nm) are: 19.8/20.3/470, 18.3/18.9/546, 17.8/18.5/589 and 17.3/17.8/650. The chemical composition is (electron microprobe data, with iron divided into Fe2O3 and FeO based on the charge balance, wt.%): MnO 0.11, FeO 1.51, V2O3 0.89, Cr2O3 0.28, Fe2O3 19.26, TiO2 37.72, Nb2O5 40.08, total 99.85. The IR and Raman spectra indicate the absence of H-, C- and N-bearing groups. The empirical formula is (Fe0.082+V0.053+Cr0.013+Fe0.923+Ti1.79Nb1.15)(Sigma 4.00)O-8. The crystal structure was determined using single-crystal X-ray diffraction data and refined to R = 0.048. Dmitryvarlamovite is orthorhombic, space group P2(1)2(1)2, a = 4.9825(6), b = 4.6268(4), c = 5.5952(6) & Aring; and V = 5.5952(6) & Aring;(3 )(Z = 1). The structure is related to those of wolframite-group minerals but differs in the scheme of cation ordering. The crystal-chemical formula derived based on the structural data is (Ti0.57Nb0.21Fe0.153+Fe0.042+V0.02Cr0.01)(2)(Nb0.36Ti0.33Fe0.313+)(2)O-8. The strongest lines of the powder X-ray diffraction pattern [d, & Aring; (I, %) (hkl)] are: 3.58 (40) (011), 2.911 (100) (111), 2.809 (40) (002), 2.497 (38) (020), 2.447 (29) (103), 1.7363 (32) (103) and 1.7047 (29) (220). Dmitryvarlamovite is named after Dmitry Anatol'evich Varlamov (b. 1965).

Information about the spectra of noble metal minerals obtained by Raman spectroscopy, using the example of a new copper–gold–platinum ore occurrence in the Polar Urals, is presented. For the first time, spectra of temagamite and minerals of the intermediate merenskyite–moncheite series were obtained, and some of the previously detected minerals are refined and confirmed. The prerequisites for new mineral phases of the intermediate series are noted, difficulties in using the method and the need for further development of this area of research are indicated. It is shown that the use of Raman spectroscopy, in controversial cases, complements and often clarifies the data of microprobe studies.

There is an extensive range of carbon substances with poorly ordered structures that are not well understood. Yet they are important indicators of conditions of related geological processes. The carbon minerals include nanocrystalline graphite, natural analogs of glass-like carbon (GLC)—shungite and impact ultrahigh-pressure GLC, recently discovered ultranocrystalline diamond, as well as natural carbon nanocomposites of diamond, lonsdaleite, and graphite. Studying these natural carbon substances using a standard Raman approach with excitation by visible radiation may lead to a significant distortion of the understanding of their phase states. This paper presents in detail for the first time the spectral features of natural, poorly ordered, and multiphase sp2-sp3 carbon composites by multi-wave Raman spectroscopy using laser excitations from visible to ultraviolet light applied to natural low-ordered carbon substances—nanocrystalline graphite and shungite, nanocrystalline and ultranocrystalline diamond, and multiphase carbon aggregates. The carbon state resolution advantages of ultraviolet Raman spectroscopy for phase analysis of nanostructured and poorly ordered polycomponent carbon substances containing sp2- and sp3-carbons are presented. Raman spectroscopy with ultraviolet excitation can also be applied in the analysis of industrial carbon materials, such as glassy carbon and functional carbon nanocomposites, including ultranocrystalline diamond, lonsdaleite, and amorphous sp3-carbon components.

Zircon is an important source of genetic information. The purpose of the research is a detailed study, identification of diagnostic features, and determination of the evolution of the composition of zircon, which will make it possible to establish the sources of clastic material and the conditions for the formation of the paleontologically mute terrigenous Dzhezhim Formation on the Dzhzhimparma Rise (Southern Timan). The article presents the results of the study of zircon from the Upper Proterozoic metasedimentary deposits of the South Timan by Raman spectroscopy. According to morphological features, chemical composition, internal structure and degree of crystallinity, four types of zircon have been distinguished. The Raman spectra of all morphological types of the studied mineral was surveyed. A comparative analysis of the Raman characteristics showed that the first type is characterized by the highest degree of crystallinity, the third type is characterized by the minimum, and the second type occupies an intermediate position. The fourth type is a unique highphosphorus zircon, the nature of its spectra reflects the presence of Y, P, REE, and other impurity elements, and also indicates its metamictization as a result of radiation damage to the structure. Morphological features, differences in the chemical composition and characteristics of the Raman spectra of the distinguished types of zircon indicate the difference in the sources from which they entered the sedimentary rock. The source of type I zircon could be felsic igneous rocks. Type II and III zircons are probably of metamorphogenic origin. The formation of the modern composition and appearance of zircons of the fourth type, the formation of which is associated with a high-temperature magmatic source, is due to multiphase transformations in hydrothermal-metamorphic and epigenetic processes. We believe that type IV zircons have the longest history of existence. This is evidenced by their high metamict, i.e., the destruction of the crystal lattice under the action of U and Th radiation, which depends on their number and the age of zircon grains. It is known that the age of zircon of the Dzhezhim Formation is pre-Upper Riphean; during its existence, the mineral was repeatedly subjected to various external influences that changed the parameters of its crystal structure.

The paper presents results of petrographic, geochemical, mineralogical, and isotope-geochronological studies of metagabbro-dolerites of the central part of the Kara Depression, located in the middle course of the Sopcha-Yu River in the Yugorsky Peninsula, Nenets Autonomous District, Russia. Two varieties of metagabbro-dolerites are distinguished: quartz-bearing and quartz-free. The influence of an impact event on rock-forming and accessory minerals is considered. It is proved that the impact event has not modified the isotope system of zircon in the metagabbro-dolerites. The U–Pb (LA-ICP-MS) isotope–geochronological dating of the zircons gives an age of the magmatic minerals within the range of 365.3 to 390.8 Ma, which seems to correspond to the age of the massif. The weighted mean age is 375.5 ± 2.6 Ma and likely corresponds to the age of the Hengur complex.

We present a novel study of fluid inclusions in the vein quartz of the Kyvvozh gold placer field and in the quartz of gold-quartz intergrowths from the placer (methods of homogenization, cryometry, and Raman spectroscopy were used). We determined that in vein quartz the homogenization temperature of fluid inclusions fluctuated in the range of 220–425 °C, the liquid phase was represented by aqueous solutions, predominantly sodium and magnesium chloride. The homogenization temperature of fluid inclusions in quartz of gold–quartz intergrowths is 220–330 °C, and an aqueous solution of sodium chloride predominates in the liquid phase. Mineral formation proceeded in two stages: at the first stage, the fluid was enriched with nitrogen, at the second stage — with carbon dioxide.

The results of studies of marine sponge carbonization processes during thermal treatment in an argon atmosphere in the temperature range from room temperature to 1200 °C are presented. The spatial structure, atomic composition of native and carbonized sponges, and their changes during pyrolysis were characterized using a set of methods that are informative at the macro- (thermogravimetric analysis, derivative thermogravimetric analysis, differential scanning calorimetry), micro- (Raman spectroscopy, scanning electron microscopy, energy dispersive spectroscopy), and nanoscales (X-ray absorption and photoelectron spectroscopy using synchrotron radiation and a sample charge compensation system). Preservation of the 3D architecture at the macro- and microlevels and graphitization of the interfibril medium with the formation of turbostratic graphite at the nanolevel were demonstrated. It was shown that the atomic contents of nitrogen, carbon, and oxygen in the spongin were ~2–3 at.%, ~5 at.%, and ~4 at.%, respectively. The matter concentrated in the space between the spongin fibrils included ~70 at.% carbon and ~11 at.% oxygen, with a large proportion of carbon (~63 at.%) involved in the formation of aromatic and C–C bonds and the remainder in carbon monoxide compounds. After the decomposition of spongin at 400 °C, this substance transformed into turbostratic graphite, preserving the 3D architecture of the original marine sponge as the temperature rose.

Ultrahigh-pressure high-temperature glasses are characterized by unusual structural and phase aspects that require closer investigation in order to elucidate their physical properties and the possibility of using innovative materials as prototypes. Experimental modeling of an impact process in laboratory conditions makes it possible to shed light on the nature of phase transformations on impacto-genesis. Impact glasses were obtained experimentally by melting the aluminosilicate and quartz components of the rocks of the target of the Kara astro-problem at pressure about 90 GPa and temperature about 7000°C. Investigations have shown that as a result of extreme external conditions, glasses of a specific composition are formed containing a high proportion of Ca and carbon. Thus, the results obtained indicate the possibility of obtaining glass of wide compositions, including carbon-containing glass, which can be used for further research in order to develop new materials and technologies for their production.

Fluid inclusions in quartz and lazulite (Mg,Fe2+)Al2(OH,PO4)2 were studied for the first time in the quartz‒lazulite‒hematite-tourmaline veins of Mt. Chernaya, the Nether-Polar Urals. It was found that they are very similar. Homogenization of the most inclusions occurs at 155‒220°C in lazulite and at 147‒235°C in quartz; and salinity varies between 12.5‒15.0 and 10.7‒15.7 wt % NaCl eq., respectively. The eutectic temperature of the water‒salt solution in both cases ranges within ‒31 … ‒40°C, which indicates the presence of magnesium, sodium, and iron salts in the mineral-forming fluid. The gas phase of fluid inclusions is represented by carbon dioxide and nitrogen in approximately equal proportions.

The results of the comparative quantitative study of oxygen-containing groups adsorbed on the surface of carbonized sponge scaffold (CSS), highly oriented pyrolytic graphite (HOPG), fullerite C60 and multi-walled carbon nanotubes (MWCNTs) introduced into a high vacuum from the atmosphere without any pre-treatment of the surface are discussed. The studied materials are first tested by XRD and Raman spectroscopy, and then quantitatively characterized by XPS and NEXAFS. The research results showed the presence of carbon oxides and water-dissociation products on the surfaces of materials. It was shown that main source of oxygen content (~2%) on the surface of HOPG, MWCNTs, and C60 powder is water condensed from the atmosphere in the form of an adsorbed water molecule and hydroxyl group. On the CSS surface, oxygen atoms are present in the forms of carbon oxides (4–5%) and adsorbed water molecules and hydroxyl groups (5–6%). The high content of adsorbed water on the CSS surface is due to the strong roughness and high porosity of the surface.

At the stage of magmatic crystallization, magmas of basic–ultrabasic intrusions of subduction origin and alkaline-ultrabasic intrusions have high oxygen fugacity, which prevents large-scale sulfide formation. Correspondingly, PGE in such intrusions are dispersed among cumulus minerals rather than accumulated in sulfides. It has been shown experimentally that the subsolidus interaction (P = 200 MPa, T = 950°C) of CO2 with olivine, a typical cumulus mineral of basic–ultrabasic intrusions, leads to the oxidation of the fayalitic component and reduction of a fluid. At a low silica activity in the fluid, the content of CO in CO2 reaches a maximum value of 14 mol %, which corresponds to fO2 = QFM–2. With such a CO content, platinum from the capsule walls was dissolved in the fluid in the form of carbonyl and reprecipitated with spinel in olivine cracks. It has been experimentally established that the interaction of CO2–H2O fluid with pyrrhotite under the same P-T conditions is accompanied by the reduction of the fluid with a decrease in oxygen fugacity to QFM buffer. Analysis of the composition of fluid captured in an albite glass trap by micro-Raman scattering showed the formation of saturated (С2Н6 and СН4) and unsaturated (with functional groups СН=СН and =СН2) hydrocarbons, CO, H2 and H2S. The platinum of the capsule walls has buffered the sulfur fugacity at a low level of Pt–PtS buffer, resulting in the low content of sulfur species in the fluid and dissolution of Pt in carbonyl form. Crystallization of the isoferroplatinum from such a fluid was observed experimentally. Preliminary data indicate that the CO-bearing carbonic fluid extracts Cr from the Cr-spinel, which increases the range of the Cr/(Al + Cr) ratio with constant Fe3+/(Al + Cr) at the spinel surface. All established experimental effects of fluid interaction with cumulus minerals of the basic–ultrabasic intrusions have been found in nature. This supports the inferred important role of such interaction in the formation of the low-sulfide PGE deposits.

The results of the research of a composite based on multi-walled carbon nanotubes (MWCNTs) decorated with CuO/Cu2O/Cu nanoparticles deposited by the cupric formate pyrolysis are discussed. The study used a complementary set of methods, including scanning and transmission electron microscopy, X-ray diffractometry, Raman, and ultrasoft X-ray spectroscopy. The investigation results show the good adhesion between the copper nanoparticles coating and the MWCNT surface through the oxygen atom bridge formation between the carbon atoms of the MWCNT outer graphene layer and the oxygen atoms of CuO and Cu2O oxides. The formation of the Cu–O–C bond between the coating layer and the outer nanotube surface is clearly confirmed by the results of the O 1s near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) of the Cu/MWCNTs nanocomposite. The XPS measurements were performed using a laboratory spectrometer with sample charge compensation, and the NEXAFS studies were carried out using the synchrotron radiation of the Russian–German dipole beamline at BESSY-II (Berlin, Germany) and the NanoPES station at the Kurchatov Center for Synchrotron Radiation and Nanotechnology (Moscow, Russia).

The fullerite C60 modified by hot isostatic pressing (HIP) at 0.1 GPa in argon near and beyond its thermal stability region (920–1270 K temperature interval) was studied by X-ray diffractometry, Raman spectroscopy, ultra soft X-ray photoelectron and near edge X-ray absorption fine structure spectroscopy. It was found that the C60 molecules merge into closed nanocapsules with a graphene surface during the thermal treatment. The conducted studies showed that using HIP treatment of the fullerite C60, it is possible to obtain a chemically resistant material with a high hardness and elasticity, as well as a density lower than that of the graphite. This new material, consisting of closed graphene nanocapsules 2–5 nm in size, formed by sp2 covalent bonds between carbon atoms is promising for various applications, and as a basis for the synthesis of new composite materials.

Abstract X‑ray computed microtomography (CT) of impact rock varieties from the Kara astrobleme is used to test the method’s ability to identify the morphology and distribution of the rock components. Three types of suevitic breccias, clast-poor melt rock, and a melt clast from a suevite were studied with a spatial resolution of 24 μm to assess CT data values of 3D structure and components of the impactites. The purpose is first to reconstruct pore space, morphology, and distribution of all distinguishable crystallized melt, clastic components, and carbon products of impact metamorphism, including the impact glasses, after-coal diamonds, and other carbon phases. Second, the data are applied to analyze the morphology and distribution of aluminosilicate and sulfide components in the melt and suevitic breccias. The technical limitations of the CT measurements applied to the Kara impactites are discussed. Because of the similar chemical composition of the aluminosilicate matrix, glasses, and some lithic and crystal clasts, these components are hard to distinguish in tomograms. The carbonaceous matter has absorption characteristics close to air, so the pores and carbonaceous inclusions appear similar. However, X‑ray microtomography could be used to prove the differences between the studied types of suevites from the Kara astrobleme using structural-textural features of the whole rock, porosity, and the distributions of carbonates and sulfides.