The thermal behavior of aqueous sulfate NaHSO4·H2O and the product of its dehydration α‑NaHS-O4 is studied. The studies are carried out using high temperature X-ray diffraction and complex thermal analysis. Based on the data of three experiments, the temperature, nature, and sequence of phase transformations are established: NaHSO4·H2O(30–50°C) → α-NaHSO4(140–180°C) → Na2S2O7 + Na3H(SO4)2. With increasing temperature increasing in the NaHSO4·H2O structure hinge deformations occur at the level of a chain of NaO3(OH)(H2O)2 polyhedra. The anisotropy of thermal expansion is αmax/αmin = 1.9 for NaHSO-4·H2O and αmax/αmin = 1.3 for NaHSO4.

We studied phenocrysts and melt inclusions in order to evaluate physical and chemical conditions of petrogenesis of the Sulawesi Island (southwestern Pacific) basalts. The compositions of the phenocrysts of clinopyroxene and plagioclase hosted by basalts of the Lokon volcano indicate two types of melts: primitive and differentiated. Primitive magmas produced high-anorthite plagioclases that are absent from the Lokon volcano andesites. The second type of melts produced compositionally similar clinopyroxenes and plagioclases of both basalts and andesites. Similarities in compositions of homogeneous glasses of melt inclusions in minerals from the Lokon volcano and other volcanoes of the Sulawesi Island and the SW Pacific suggest similar P-T conditions for the formation of magmatic systems. In particular, the data on inclusions demonstrate that basaltic magmas of the Lokon and Soputan volcanoes are primitive melts (SiO2 = 48.2–51.5 wt.% and MgO up to 8 wt.%), which is consistent with the content of other oxides. These inclusions plot at the beginning of the «andesitic» trends in variation diagrams. Accordingly, these melts could be primary melts for the development of the entire magmatic system that formed andesitic to basaltic effusive rocks of the Tondono caldera and the Lokon and Soputan volcanoes. Based on the compositions of both, melt inclusions and their host minerals in Lokon basalts, we concluded that clinopyroxene phenocrysts crystallized at two levels: 20.6–14.5 km (1150–1130°С) and 13–6 km (1145–1105°С), and plagioclase phenocrysts crystallized at 1160–1120°С. In general, our data on melt inclusions and phenocrysts indicate fundamental differences in the PTX parameters of the magmatic systems that formed basalts and andesites of the Sulawesi Island. The basalt-hosted clinopyroxene phenocrysts crystallized from compositionally stable melts at a slightly decreasing temperature with a significant pressure drop during magma ascent. Phenocryst crystallization in andesites proceeded differently: with delays at constant pressures in deep intermediate chambers and a significant drop in temperature, which facilitated the processes of fractionation and evolution of melts.

The ferromagnetic resonance (FMR) in the frequency range of 0.5 to 12.5 GHz has been investigated as a function of external magnetic field for rapidly quenched Fe3Co67Cr3Si15B12 amorphous ribbons with different features of the effective magnetic anisotropy. Three states of the ribbons were considered: as-quenched without any treatment; after relaxation annealing without stress at the temperature of 350 °C during 1 h; and after annealing under specific stress of 230 MPa at the temperature of 350 °C during 1 h. For FMR measurements, we adapted a technique previously proposed and tested for the case of microwires. Here, amorphous ribbons were studied using the sample holder based on a commercial SMA connector. On the basis of the measurements of the reflection coefficient S11, the total impedance including its real and imaginary components was determined to be in the frequency range of 0.5 to 12.5 GHz. In order to confirm the validity of the proposed technique, FMR was also measured by the certified cavity perturbation technique using a commercial Bruker spectrometer operating at X-band frequency of 9.39 GHz. As part of the characterization of the ribbons used for microwave measurements, comparative analysis was performed of X-ray diffraction, optical microscopy, transmission electron microscopy, inductive magnetic hysteresis loops, vibrating sample magnetometry, magneto-optical Kerr effect (including magnetic domains) and magnetoimpedance data for of all samples.

In the alloy Fe 63.5 Ni 10 Cu 1 Nb 3 Si 13.5 B 9 , which is conventional FINEMET with Fe replaced by 10 at % Ni, the effects of the temperature and time of nanocrystallizing annealing in the presence of tensile stresses (stress annealing, SA) on the magnetic properties, magnetic anisotropy, and structure are considered. In the entire studied SA temperature range (480–550°С), induced magnetic anisotropy (IMA) of the easy-plane type occurs in the studied alloy. The tensile stresses upon SA were 200 MPa. In the course of SA at the minimum temperature, anisotropy with the minimum IMA constant (200 J/m 3 ) is induced. The maximum SA duration, i.e., 4 h, is required. At SA temperatures of 540–550°С, 10 min is sufficient to induce IMA with the maximum constant ~2000 J/m 3 . It is shown that the structural state (phase composition) is correlated with the magnetic properties and IMA. Thus, the increase in the coercivity with an increase in the SA duration at 540–550°С (as well as at 520°С) is due to the development of the tetragonal phase in the alloy. The α‑(Fe,Ni)Si solid solution and Fe 3 Si phases form upon treatment for 10 min. The decrease in the IMA constant with an increase in the SA time at 540–550°С from 10 min to 1 h is most likely due to the change in the volume fractions of the structural components of the alloy with negative and positive magnetostriction.

The effect of 10 at % Ni, which was introduced into the classic Finemet Fe73.5Cu1Nb3Si13.5B9 at the expense of the Fe content, on the magnetic properties of the composition has been considered. The alloy was subjected to nanocrystallizing annealing in the presence of tensile stresses and in their absence. It is shown that, similarly to the Ni-free alloy, in the Fe63.5Ni10Cu1Nb3Si13.5B9 alloy subjected to thermomechanical treatment, the magnetic anisotropy with the easy magnetization direction across the ribbon axis (transverse induced magnetic anisotropy) is induced. It was found that the 10 at % Ni addition almost does not affect the value of magnetic anisotropy constant induced under thermomechanical treatment and decelerates the process of magnetic anisotropy inducing at σ ≤ 200 MPa. The Ni-containing alloy subjected to nanocrystallizing annealing (at 520°C) in the presence of tensile stresses and in their absence demonstrates the more than 200-fold increase in the coercive force as the annealing time increases from 1 to 4 h, whereas the coercive force of the Ni-free alloy is almost unchanged. This is likely to be related to the appearance of new structural components in the Ni-alloyed composition upon annealing.

The structure of the Fe63.5Ni10Cu1Nb3Si13.5B9 alloy, which is a classic alloy of the FINEMET type with 10 at % Ni substituted for Fe, has been studied after crystallization in the presence of tensile stresses. It has been shown that, upon the crystallization of the alloy (520°C) both in the presence of a tensile load and without it, nanocrystals of an α-(Fe, Ni)Si solid solution and of the Fe3Si phase are formed with an increase in the duration of annealing from 10 min to 1 hour. When the length of the annealing is further increased from 1 to 4 hours, a tetragonal phase Fe3NiSi1.5 appears in the alloy. A relationship between the structural state (phase composition) of the Fe63.5Ni10Cu1Nb3Si13.5B9 alloy and its magnetic properties and the type of the induced magnetic anisotropy has been shown. The growth of the coercive force, which was previously observed in samples of this alloy as the duration of the annealing was increased to 4 hours, is therefore associated with the appearance of a tetragonal phase in the alloy. The transverse magnetic anisotropy, which is induced in the alloy in the process of nanocrystallizing annealing in the presence of a tensile load, is associated with the formation of nanocrystals of the α-(Fe, Ni)Si solid solution and of the Fe3Si phase with a negative magnetostriction.

The Derba block is one of the largest Precambrian terranes of the Sayan-Yenisei accretionary belt in the southwestern margin of the Siberian Platform. It is composed of metamorphosed terrigenous-carbonate rocks of the Sayan Group, injected by granitoids. The geochemical features of gneiss-schist associations indicate the low maturity of their sedimentary protoliths corresponding in composition mainly to graywackes and terrigenous-carbonate rocks (marls). According to the results of U-Pb (LA-ICP-MS) dating of detrital zircons from gneisses and schists, the sedimentary protolith formed in the Vendian. Neoproterozoic subduction complexes were probably the major provenance for terrigenous material, and Early Precambrian rocks made a limited contribution. The Ar-Ar and U-Pb isotope data testify to nearly coeval and multistage events of metamorphism (up to the amphibolite facies) and granitoid magmatism (-510-500 and 480-465 Ma) in the Derba block. These processes were reflective of the Early Caledonian orogenic processes in the structures of the Central Asian Orogenic Belt. The similarity in the composition, time of sedimentation, and provenances of metaterrigenous-carbonate complexes of the Derba block (Sayan Group), West Sangilen block of the Tuva-Mongolian massif (Erzin and Moren complexes), and the Khamar-Daban terrane (Slyudyanka Group) suggests that these structures were a single Vendian continental margin with lateral variations in depositional environments and the sources of terrigenous material. (C) 2018, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

We have analyzed the isotope-geochemical features of volcanosedimentary rocks of the Karsakpai Group in southern Ulutau (Central Kazakhstan): mafic volcanics, siliceous and siliceous-ferruginous sediments, and quartz-sericite-chlorite schists. The close association of ferruginous quartzites with intraplate volcanics indicates that they formed in a tectonically active basin. The Nd isotope composition of ferruginous quartzites was governed by synchronous underwater volcanism, whereas the Nd-143/Nd-144 value of schists was additionally controlled by the Nd isotope composition of older sources. The Mesoproterozoic Nd model ages and positive epsilon(Nd)(t) values of the metaterrigenous rocks of the Karsakpai Group indicate the presence of Mesoproterozoic juvenile material in the provenance. The minimum Nd model ages suggest the lower boundary of sedimentation of 1.3 Ga. (C) 2017, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

The Late Vendian (540–550 Ma) U–Pb zircon age of postcollisional granitoids in the Osinovka Massif was obtained for the first time. The Osinovka Massif is located in rocks of the island-arc complex of the Isakovka Terrane, in the northwestern part of the Sayany–Yenisei accretion belt. These events stand for the final stage of the Neoproterozoic history of the Yenisei Ridge, related to the completing accretion of the oceanic crust fragments and the beginning of the Caledonian orogenesis. The petrogeochemical composition and the Sm–Nd isotopic characteristics support the fact that the granitoid melt originated from a highly differentiated continental crust of the southwestern margin of the Siberian Craton. Hence, the granite-bearing Late Riphean island-arc complexes were thrust over the craton margin at a distance considerably exceeding the dimensions of the Osinovka Massif.

For the purpose of developing materials with optimum magnetic properties for high-temperature applications (500–600°C), we have investigated the magnetic properties and structure of a nanocrystalline (Fe0.7Co0.3)88Hf4Mo2Zr1B4Cu1 alloy. The alloy was subjected to nanocrystallizing annealing (NA) at 620°C in the presence of an alternating magnetic field (magnetic heat treatment, MHT). The influence of the duration of the NA and of the amplitude value H amp of the ac magnetic field on the magnetic properties of the alloy and on their thermal stability has been studied. It has been established that the MHT carried out at 620°C is most efficient after holding in a magnetic field for 20 min. In this case, a decrease in the coercive force and an increase in the remanence have been observed. An increase in the time of the holding upon the MHT from 20 min to 4 h decreases the efficiency of the treatment. It has been shown that the MHT carried out at 620°C for 2 h and H amp = 9 kA/m leads to the smallest changes in the magnetic properties of the alloy after the subsequent holding at a temperature of 550°C for 30 h. However, this treatment does not ensure the thermal stability of the magnetic properties of the alloy at 550°C achieved earlier after the nanocrystallization of the alloy at 620°C for 20 min in the presence of tensile stresses (250 MPa).

In this study we present data on the geologic setting, geochemical and isotopic compositions, timing and P-T conditions of metamorphism of Neoproterozoic terrigenous metasediments, and associated island-arc metavolcanics of the Predivinsk terrane of the Yenisei Ridge. Relatively immature terrigenous rocks were eroded from a local source which is associated with island-arc magmatic complexes. The geochronological constraints indicate that the terrigenous rocks were eroded from juvenile crustal sources represented primarily by magmatic rocks, which are similar to those of the Predivinsk terrane. This is supported by a similar range of model ages, positive eNd values of terrigenous and magmatic rocks, and correspondence between the concordant ages of detrital zircons from metasedimentary rocks (610-640 Ma) and the U-Pb ages of zircons from rhyolites (ca. 620-640 Ma) from two suites within different sequences. The P-T conditions for volcanosedimentary rocks of the Predivinsk terrane correspond to the epidote-amphibolite facies and the transition from epidote-amphibolite to amphibolite facies. The most likely age of metamorphism due to Vendian accretion/collision events is given by Ar-Ar dates of 600-610 Ma. (C) 2016, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

We consider geochemistry of Neoproterozoic metavolcanosedimentary rocks of the Bozdak Group in southern Ulutau (Central Kazakhstan) and present the first results of U-Pb LA-ICP-MS dating of clastic zircons and Sm-Nd isotope data. Isotope-geochemical and geochronological studies have shown that the Bozdak Group rocks resulted from the destruction of igneous and metamorphic complexes mostly of Neoproterozoic age with the participation of Archean and Paleoproterozoic rocks. The lower boundary of sedimentation is dated at 800 Ma. The obtained isotope-geochemical data on the Bozdak Group basaltoids suggest their formation on thick continental crust with the participation of subduction fluid. (C) 2016, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

Relative changes in the density, (d-d(0))/d, of SiO2 glass in pressures up to 5.0 GPa were compared with the (d-d(0))/d values of aluminosilicate and magnesium silicate glasses in the M2O(CaO)-Al2O3(MgO)-SiO2 system (M=Li, Na, K). It is shown that the silica glass is not the most highly compressible among the silicate glasses, as can be expected in the case of an ideal structure of SiO2 glass (the ideal structure of fused quartz is characterized by the absence of nonbridging oxygen atoms in the fully polymerized structural network, NBO/T congruent to 0). The compressibility of silica glass is below that of aluminosilicate glasses with a high content of SiO2, such as KAlSi3O8 and NaAlSi3O8 glasses. This is related to the defect structure of SiO2 glass and the possible maintainance of abnormally high density of liquid silica in glass on cooling of the melt, due to its high viscosity.

We present data on the geologic setting, mineral composition, and conditions of metamorphism of volcanics of andesite-dacite-trachyrhyodacite, leucobasalt-basalt, basalt-andesite-basalt-trachyandesite, and basalt associations in the Yenisei amphibolite-gneiss complex of the Angara-Kan terrane. We have determined the age of zircon (SHRIMP II U-Pb dating) from two samples of volcanics of the andesite-dacite-trachyrhyodacite association. The volcanics formed in the Late Paleoproterozoic (similar to 1.74 Ga) and were metamorphosed at 750 Ma. Inherited zircon and the Sm-Nd model age (2.4-2.5 Ga) of intermediate-felsic volcanics testify to their formation predominantly from the ancient crustal source. The Late Paleoproterozoic (1.78-1.74 Ga) sedimentation and volcanism in the Angara-Kan terrane followed the main collision events: high-temperature metamorphism (1.89-1.87 Ga) and formation of the first-phase granitoids of the Taraka massif (1.84 Ga). The volcanics have a predominantly bimodal character and belong to the tholeiitic and subalkalic series; this testifies to their formation in an extension setting. The formation of the volcanics of the Yenisei complex correlates with the intrusion of the intraplate granites of the Taraka massif, whereas the terrigenous sediments correlate with the sediments of the middle Subluk Group in the Urik-Iya graben. The rocks of the Yenisei complex are characterized by inhomogeneous metamorphism, which corresponds to the conditions of transition from epidote-amphibolite to amphibolite facies and to the whole PT-range of the amphibolite facies. (C) 2016, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.