Nb-rich trachytes from Virginia, shoshonite from Colorado and high-K dacite from the Bolivian Andes contain diverse suites of native metals and alloys. Virginia trachytes are differentiates of mafic within-plate magmas derived from oceanic island basalt (OIB)-type mantle sources in the post-orogenic extensional regime of the Appalachian mobile belt. Colorado shoshonite and Bolivian dacite were produced via crystal fractionation of Fe–Mg silicates from trachybasalt and basalt magma, respectively, derived from subduction-related mantle modified by either crustal contamination (both regions are underlain by thick, mature continental-type crust) or recycling of marine sediment. Metal assemblages include refractory metals (Pt with minor Fe and Cr, native W, Co–W and Fe–W alloys), Cu–Ag–Au alloys, chalcophile metals (Cu–Sn alloy, native Cu and Zn) and associated sulfides (galena). Textural evidence (metals occur as inclusions in phenocrysts, high temperatures of their formation, etc.) and compositional features of metallic phases suggest their magmatic origin. Metal-rich magmas (both mafic and differentiated) transport metals in convergent and within-plate tectonic settings and deliver ore metals to the oxidized porphyry and epithermal environments in the upper crust.

This paper presents the results pertaining to studying the properties of the photocatalytically active composition of strontium bismuthate SrBi_2.70O_5.05, SrBi_2.90O_5.35, and SrBi_3.25O_5.88 and bismuth carbonate (BiO)₂CO₃ in molar ratios 1/0.67, 1/0.56, and 1/0.37, respectively. These compositions are obtained through pyrolytic synthesis from organic precursor complexes of strontium and bismuth with sorbitol. It has been established that the synthesised powder materials absorb the light of the visible range up to 500 nm owing to the presence of a narrow-gap semiconductor strontium bismuthate. The presence of a wide-band semiconductor (BiO)₂CO₃ ensures an effective separation of electron-hole pairs. The diffuse reflection spectra (DRS) of compositions differ from the analogous spectra of a mechanical mixture of these semiconductor phases with the same composition, which allows one to assume the heterostructural structure of the semiconductor system. The same heterostructure is confirmed by the results of mapping. Catalytic particles that are synthesised at a temperature of 500°C containing 27 mass% (BiO)₂CO₃ (corresponding to SrBi_2.9O_5.35/(BiO)₂CO₃ = 1/0.56) have the greatest activity with respect to the photodecomposition of methylene blue (MB). The possibility of controlling the optical properties and photocatalytic activity of the composition is depicted due to the joint formation of the strontium bismuthate phase and the bismuth carbonate phase.

We present the results of an investigation of the distribution of of elements according to cross-section morphology, adhesion, and anticorrosive properties of PTFE-oxide layers formed by plasma-electrolytic oxidation in an Na₂SiO₃ + NaOH electrolyte with dispersive particles of PTFE stabilized by siloxane acrylate emulsion. Coatings have a structure uncharacteristic of PEO layers. The main coating mass of thickness of up to 80 μm is composed of polytetrafluoroethylene and decomposition products of PTFE particles, as well as of the emulsion. The transition layer between the metal and polymer coating has a thickness of ∼10 μm and contains oxides of aluminum and silicon. Sample weight loss after ultrasonic treatment in water is ∼1%, which indicates a satisfactory adhesion of the coating to the metal and the cohesion between coating fragments. The coatings have a complex surface with pores several tens of microns in size. After annealing in air at 200°C, pores are filled with polymer, which is accompanied by a significant improvement in the coating’s anticorrosive properties. As a result of annealing in air at 400°C, the polymer coating sublimates and the transition layer with a thickness of ∼10–15 μm remains.

The parameters of wetting of oxide coatings on titanium formed by the method of plasma electrolytic oxidation (PEO) in an aqueous silicate electrolyte with subsequent deposition of a layer of TiO₂ nanoparticles and ultrasonic treatment by a polymer–salt gel including copper and molybdenum compounds have been investigated. The effect of the oxidized surface microrelief, TiO₂ nanoparticle layer, and pore shape and size on impregnation solution spreading and the structure of the copper–molybdenum catalytic coating formed at further thermal treatment has been demonstrated. Complex oxide composites with ultradispersed catalyst particle sizes characterized with high activity in oxidation of carbon black particles have been obtained.