Home – Home – Jornals – 2010 number 2

This paper considers a destructive method of testing the strength flip-chip assemblies (in particular, photodetectors) which consists of separating one microcircuit from another with heating (not below 383 K) after thermal cycling. The method can be used to test the adhesive properties of bonding bumps, for example indium ones, in flip-chip assemblies and determine the causes of debonding in photodetectors. Examples of the causes of failures of cooled photodetectors based on HgCdTe molecular beam epitaxy are discussed.

The basic catalytic processes of hydrogen generation, which enclose the efficient use of hydrogen permeable membranes, are discussed. A variety of types of solid membranes are inspected for their suitability for hydrogen extraction from the gas mixture. The constructions of catalytic reformers with an integrated membrane module are given, and advantages of these devices relative to traditional reactors of fuel processor are discussed. The mathematical models of reaction vessels with the membrane release of hydrogen and certain of the simulation results are presented. The prospects for using catalytic reactors with membranes in the hydrogen energetics and transportation facilities are discussed.

Granulometry, morphology data and data on mineral composition of aerosol particles are given. These have been obtained with the use of scanning electronic microscope LEO 1430 VP that was furnished with energy dispersive spectrometer OXFORD. Mineral-geochemical indicators of local sources of aerosol pollution under conditions of a megacity have been determined using ICP-MS, ICP-AES, XRD-SI, atomic absorption, and phase X-ray diffraction methods. Mobility of toxic elements that were accumulated in a snow covering has been found. A comprehensive approach has allowed us to estimate the contribution of particular commercial manufacturers to the general ecological condition of Novosibirsk.

Composition and rheological behaviour of asphalt-resin-paraffin depositions that were excreted from high-wax oils under changes of temperature gradient of oil and adsorbing surface has been studied.
An effect of petroleum composition and temperature on the quantity, composition, and rheological behaviour of oil sediments has been demonstrated.

Methods of chromatography mass spectrometry and microcolumn high performance liquid chromatography have been used to study complex biological systems. Potentialities to apply these methods have been disclosed by the example of biochemical research of symbiotic community of the endemic Baikal sponge Lubomirskia baicalensis (Dybowsky, 1874) when it is kept both under natural and under simulated conditions. It has been demonstrated that the use of a complex of modern methods of biochemical analysis allows effective, rapid determination, high sensitivity detecting of changes in biologically active compounds in living organisms.

Original data that were obtained by means of microcolumn reversed-phase high performance liquid chromatography method have been presented on content of liposoluble vitamins (A, D, E, F) in muscles and liver of big golomyanka Comephoeng baicalensis.

Based on data for component composition of the source natural gas, external pressure, and temperature, the structure of hydrates of natural gas has been found for the main gas and oil fields of Yakutia. It has been determined that the total amount of gas in 1 L of gas hydrate ranges from 160 to 250 L.

Panzerina lanata subsp. argyracea (Kuprian.) Krestovsk. is a valuable drug plant that grows in Khakassia. It contains a complex of biologically active compounds including flavonoids. Resources of panzerina raw material steadily go down owing to anthropogenic load. Its domestication solves the problem of its preservation. A wild-growing cenopopulation with the greatest content of flavonoids in the aboveground part has been revealed that is of interest as a starting material for plant introduction. The content of flavonoids in particular members of plants Panzerina lanata subsp. argyracea that grows in various cenopopulations of Khakassia and under conditions of plant introduction has been examined. Dynamics of accumulation of flavonoids for strange silvery panzerina has been determined in various vegetation phases. It was found that plants in the crop exhibit a high level of variability in their content of flavonoids.

An environmentally sound method to produce microcrystalline cellulose (MCC) has been developed. Conditions have been adjusted that make it possible to produce top-quality MCC with a good yield. The produced MCC is highly competitive with commercial samples in its performance. By means of combined mechanical activation of piroxicam and MCC that was obtained following a new technology, compositions have been prepared that offer higher than usual speed of dissolving of a medicinal substance. It has been demonstrated that "graft complexes" are formed between MCC and piroxicam as a result of interaction of the ingredients to form hydrogen bonds.

The possibility to prepare bimetallic catalysts Fe-Ni, Fe-Co and Co-Cu through thermolysis of binary complex salts involving a complex cation of one metal and a complex anion of other one is discussed, and their catalytic properties in Fischer-Tropsch synthesis are presented. Our study revealed that deposition of binary complex salts having composition [Ni(NH₃)₆]₃[Fe(CN)₆]₂, [Co(NH₃)₆][Fe(CN)₆] and [Co(NH₃)₆]₂C₂O₄[Cu(C₂O₄)₂]₂ on to the surface of aluminium hydroxide and subsequent thermolysis of the obtained composition give the chance to have metallic particles of size 15-40 nm fixed on the surface of aluminium oxide. In the case of binary complexes Ni-Fe and Co-Fe, the formation of bimetallic particles of size 15-16 nm and respective structures FCC and BCC is observed. Break-up of complexes proceeds in several sequential exothermic stages. The catalytic properties of bimetallic particles Fe-Co of BCC structure, which are prepared by thermolysis of [Co(NH₃)₆][Fe(CN)₆] + Al(OH)₃ composition, differ essentially from the literature data for Co-Fe catalysts by the reduced activity of the prepared particles with respect to the secondary processes for hydrogenation of olefins. This feature manifests itself in the extremely high selectivity of the process in relation to olefines and its anomalous temperature dependence. A rise in the process pressure up to 10-20 atm leads to significant changes in catalytic properties of bimetallic Co-Fe catalysts, among them the loss of selectivity in relation to olefins and the decrease in the rate of secondary process of vapour conversion of CO. The pressure dependence of process passing character is caused by variation in structure of catalytically active component under the action of reagents.

Indirect electrochemical oxidation of benzene by intermediates has been studied. The intermediates were generated in situ from О₂, Н₂О, and Н₂О₂ with the use of anodes from platinum, lead dioxide, and ruthenium-titanium oxide anode in water solutions with various рН. Schemes with in situ generated Н₂O₂ from О₂ and with Н₂O₂ adding to electrolyte have been implemented. It was found that hydroxylation of benzene to produce phenol with a gas diffusion cathode from commercial-grade carbon that generates Н₂О₂ from О₂ in situ is ineffective because of the cathode passivation. On Н₂О₂ addition into the electrolyte, oxidation of benzene occurred with mineralization to yield СО2 and Н2O; the oxidation state could amount from 94.8 % (Pb/PbO₂, рН 2) to 63.5 % (Pt-anode, рН 2.8, С_Fe2+ = 7.1 ⋅ 10^-6 mg/L). Efficiency of oxidation drops owing to the formation difficult-to-oxidize carboxylated complexes of iron.

Thermal conversions of sapromixite from Barzas deposit in an inert medium, hydrogen medium, and that of synthesis gas have been studied in a flow-through reactor under atmospheric pressure and in an autoclave under a pressure of up to 7 MPa. A higher conversion level of brown coal as compared with sapromixite is determined by a low metamorphic degree of brown coal and by its high content of highly reactive oxygen-bearing fragments. However, the yield of resins from sapromixite in a temperature range of 450-850 ^oC is 3-4 times higher when compared to the yield from brown coal. It has been found that an increased yield of resins under variations in heat treatment conditions is caused for the most part by a decrease in the formation of gases and water. The yield of semicoke has no any significant changes. The process flow diagram has been suggested that explains the observed effects. It has been demonstrated that unlike heat treatment in an autoclave, when employing a flow-through reactor and atmospheric pressure, the composition of the gas medium has no tangible effect on the conversion level of combustible. Meanwhile, the liquid yield at a temperature of devolatilization of coal, 650 ^oC, in a current of hydrogen and synthesis gas is at least 1.5 times higher by comparison to the yield in devolatilization of coal in an inert medium. A procedure of devolatilization of sapromixite has been suggested that affords an enhanced liquid yield as compared with the conventional process by way of using the products of gasification of a fixed residue of the process as the gas heat carrier.

Results of mass spectrometer determination of the comprehensive group content and molecular-mass distribution of hydrocarbons of 30 various structural types in lower Cretaceous oils of East Gobi and Tamsag oil rich provinces of Mongolia have been presented. Hydrocarbon types of oils according to three current ways of classification have been determined; factors responsible for the distinctions in types of oils being determined by these ways have been found.

The role of the hydrodynamic cavitation for initiating and supporting chain-radical reactions of oxidation of organic substrates, among them 4-nitrophenol (4-NP), with Fenton's reagent (H₂O₂ + Fe²⁺) has been shown. Fe²⁺ ions were supplied into solution by dissolving split steel shot or steel chips in cavitation reaction vessel. At initial concentrations of 4-NP and H₂O₂ of 6.7 ⋅ 10^-5 and 4.02 ⋅ 10^-4 mol/L, respectively, the degree of phenol conversion at pH 3.4 reaches 98 %. The diagram of the set-up designed to treat sewage with productivity 0.5 m³/h and the description of the equipment for cavitation generation are presented.

The possibilities for sublimation of silicon and aluminium - basic components of refractory aluminium silicates - to gas phase have been demonstrated by way of thermodynamic computations and experiments with minerals of sillimanite tribe. The proposed method is founded on alternate action of chlorine on aluminium silicates in the presence of carbon-bearing reductant and aluminium subchloride as a reductant, with the results that low-boiling salts of aluminium and silicon are produced. This method was demonstrated to be economically feasible by direct expenditure of electric energy on the return of aluminium subchloride to the cycle solely in the case of joint production of aluminium and silicon from minerals of sillimanite tribe.

Content of toxic heavy metals (Ni, Cr, Cd, Co, Pb) in the rock-soil-plant system in forest steppe of Transbaikalia has been studied. It was found that it does not exceed percent abundance values and MPC of soils and plants.

A full potential FLAPW-GGA method is used to study for the first time the electronic structure of cubic tungsten subnitride W₂N, and its equilibrium lattice parameter, density, energy of cohesion, coefficients of low temperature heat capacity and Pauli paramagnetic susceptibility are calculated. It is discussed in comparison to the similar values of hexagonal and cubic tungsten mononitrides WN.

The character of alkaline (M⁺= Li, Na, K) and alkaline earth metal ions (M²⁺= Be, Mg, Ca) interactions with disilyne and acetylene has been studied by using high-level ab initio computations. The interaction energies were calculated at MP2/6-311++G(2d,2p) level. These calculations show that the size and charge of cation are two significant factors that affect the character of interaction. AIM and NBO analyses of Mⁿ⁺…X₂Y₂ interactions specify that the variation of densities and the extent of charge transfers upon complexation correlate well with the obtained interaction energies.

By the example of combined calculation methods (CCMs) corresponding to calculations in MP4/6-311+G(fd,p)//MP2/6-31G(d,p) and MP4/aug-cc-pvTZ//МР2/cc-pvDZ approximations the factors affecting their accuracy are considered. By total energy calculations made for a number of compounds it is shown that the accuracy of CCMs reduces when valence double- and triple-split basis sets are applied together, and also when different methods are used to allow for electron correlation. The use of empirical corrections taking into account the character of the electron distribution in a molecule allows an enhancement of the accuracy of CCMs. The mentioned factors taken into account enable us to obtain CCM, for which the mean absolute deviation of calculation data is 1.0 kJ/mol and the largest maximum deviation is 8.0 kJ/mol in the total energy calculation in the MP4/6-311+G(f,d,p) approximation.

The vaporization enthalpies of mono- and dicarbonic acids with different structures are calculated under normal conditions using the modified Randič method and the energies of hydrogen bonds. The results demonstrate good agreement between the experimental and calculated data.

Gas electron diffraction at a temperature T of 641(5) K is used to study the structure of an N,N′-ethylene-bis(salicylaldiminato) zinc(II) molecule, ZnO₂N₂C₁₆H₁₄, further Zn(salen). The structure of a gaseous Zn(salen) complex has C₂ symmetry and is characterized by a substantial turn of two chelating fragments of the ligand with respect to each other, and also by a big difference in the length of coordination bonds: r_h1(Zn-O)=1.902(7) Å and r_h1(Zn-N)= 2.027(7) Å. Results of the DFT/B3LYP calculation with 6-31G* and CEP,TZV basis sets of the molecule structure well agree with the experimental data. The electronic structure of Ni(salen), Cu(salen), Zn(salen), and Zn(acacen) molecules is considered.

Nonempirical methods are used to calculate the geometric parameters, the frequencies of normal vibrations, and thermochemical characteristics of ions existing in saturated vapors over sodium bromide and iodide: Na₂X⁺, and (X = Br, I). According to the calculations, Na₂X⁺ and triatomic ions have a linear equilibrium configuration of D_∞h symmetry. Pentaatomic ions can exist in the form of three isomers: linear with D_∞h symmetry, planar cyclic with С_2v symmetry, and bipyramidal with D_3h symmetry. At a temperature of ~1000 K, and pentaatomic ions are shown to be present in vapor mainly in the form of linear isomers. The energies and enthalpies of ion molecular reactions with the participation of the above ions are calculated, and the formation enthalpies of the ions are determined, Δ_fH°(0 K): 293±2 kJ/mol (Na₂Br⁺), 354±2 kJ/mol (Na₂I⁺), -536±2 kJ/mol -458±2 kJ/mol 24±5 kJ/mol 143±5 kJ/mol -810±5 kJ/mol and -675±5 kJ/mol

In the microwave spectrum of a 5-methyl-1,3-dioxane sample, the rotational transitions of а and с types with 4 ≤ J ≤ 11 for five isotopomers of a molecule with ¹³С and ¹⁸О isotopes in different sites are identified in a frequency range of 18 GHz to 42 GHz. The spectroscopic constants of isotopomers are found. The substituted r_s and effective r_о structural parameters of 5-methyl-1,3-dioxane are determined. By the B3PW91/aug-cc-pVDZ density functional method the equilibrium structure of the molecule is calculated. The results of quantum chemical calculations are compared to the experimental data.

The UV induced photopolymerization of Langmuir-Blodgett films of lead salt of 2-docosynoic acid (CH₃(CH₂)₁₈C≡CCOOH) is studied using IR and Raman spectroscopy. It is found that the films are a highly ordered system with trans-configuration of alkyl chains and a bridged complex generated between the carboxyl group and the lead ion. Based on a change in the absorption band intensity in the IR spectra corresponding to the triple bond vibration, the degree of polymerization depending on the irradiation time is determined. In the Raman spectra, a peak at ~1635 cm^-1 appears during polymerization, which corresponds to the C=C double bond. The formation of conjugated double bonds in these systems is observed for the first time. During polymerization, methylene chains of molecules retain trans-configuration; the structural ordering of molecules in the film is observed.

The synthesis of alkyl 2-chloro-3-formylacrylates 1 from alkyl pyruvates was carried out using Vilsmeier reaction. The reaction is highly stereoselective and leads to a 95:5 mixture of Z and E stereoisomers. Both stereoisomers were characterized by ¹H and ¹³C NMR. In CDCl₃ solution, the NMR data, particularly the NOEDIFF experiments, show that the major species formed is the Z stereoisomer. Heating compound 1 in THF at reflux afforded the cyclic product 2 in 90 % yield. The interpretation of the experimental data were further supported by DFT/B3LYP calculations.

Based on the density functional quantum chemical calculations, the electronic structure of binuclear manganese decacarbonyl Mn₂(CO)₁₀ is analyzed. The calculation results are used to interpret the CKα, OK_α, MnL_α, and X-ray fluorescence spectra of Mn₂(CO)₁₀. The theoretical fluorescence spectra constructed using these calculations are in good agreement with the experiment

The paper analyzes the physical implications of the result obtained in the work [1] that a random variable - the number of the nearest neighbors M_λ in a fluid consisting of N hard spheres in the Gibbs canonical ensemble - can be expressed as a sum of N independent and similarly distributed random variables. The mean value of a functional of this random variable determines the free Helmholtz energy of a fluid with the SW interaction potential (hard sphere plus square well). The paper shows that the said property of the random variable M_λ allows one to average this functional using the general methods of the probability theory (the Cramer theorem or the method of large deviations) without expanding it in a perturbation theory series. All the mathematical variables introduced in the proof of the Cramer theorem have a simple physical meaning and are determined by the thermodynamic characteristics of the SW fluid. The conditions of the Cramer theorem are shown to hold in the entire region of the fluid existence except the critical point area.

A method to construct model radial distribution functions (RDFs) fr om the already known structural data is described. The method includes the procedures to calculate termination ripples that always appear on the experimental RDF because of the bounds of the integration lim its in the Fourier transformation of the X-ray scattering curve. The introduction of this procedure increases the accuracy of the comparative RDF method used to elucidate the phase composition of nanodispersed materials and to determine the features of the local structure of the phases as compared to their well crystallized analogues. Cerium dioxide samples with different dispersion exemplify the applicability of this method to determine the features of the local structure.

Two approaches to the description of changes in the bond length in molecules and crystals with changing coordination number of atoms are studied. They are based on a difference or ratio of interatomic distances when the structure is changed. The second approach is shown to yield more accurate results. The change in the interatomic distances in polar compounds has the same character as the change in the ionic radii when coordination numbers are varied.

A new fluorine-containing tetradentate ligand 1,2-bis(5,5,5-trifluoro-4-oxopent-2-en-2-amino)benzene and its complexes with Ni(II), Pd(II) and Cu(II) are characterized by single crystal X-ray diffraction. It is found that the enaminoketone fragments of the ligand are identical in bond lengths and angles; they are almost planar, and make the angles of 51.3° to the plane of the benzene ring. The structures of Ni(II), Pd(II), and Cu(II) complexes are similar and have a saddle-shape configuration. The metal ions have square planar coordination and are located almost in the center of the N₂O₂ square. The average M-N bond lengths are longer than M-О ones by 0.014 Å and 0.034 Å for the Ni(II) and Cu(II) complexes respectively, while in the Pd(II) complex, M-О is longer than M-N by 0.029 Å. The average chelate angles N-M-O in the complexes are: N-Ni-O 95.12°; N-Pd-O 95.68°; N-Cu-O 93.88°.

A neutral complex of palladium(II) with 2,9-dimethyl-1,10-phenanthroline [Pd(2,9-Me₂-phen)Cl₂] (goldish orange colored) is examined by single crystal X-ray diffraction. The crystals of [Pd(2,9-Me₂-phen)Cl₂] are monoclinic and belong to the space group P2₁/n (a = 11.8670(7) Å, b = 7.8195(5) Å, c = 14.2418(9) Å, β = 92.5450(10)°, Z = 4, V = 1320.25 ų, R = 0.0289). The complex [Pd(2,9-Me₂-phen)Cl₂] exhibits a strong distortion of the usual square-planar geometry with a deviation of the central Pd²⁺ ion and two chloride acido-ligands from the plane of coordinated 2,9-dimethyl-1,10-phenanthroline. The lengths of two Pd-N bonds are slightly different and are 2.058 Å and 2.067 Å, the lengths of the Pd-Cl bonds are equal and are 2.285 Å. 2,9-Me₂-phen itself also suffers some distortion of the planar geometry resulting in the boat conformation of the molecule. The crystal structure of the [Pd(2,9-Me₂-phen)Cl₂] complex is characterized by the presence of π-π stacked dimers arranged in infinite tilted stacks.

The reaction of lacunary arsenitotungstate [AsW₉O₃₃]^9- with [M₃S₄(H₂O)₉]⁴⁺ in aqueous solution leads to the formation of the complex [{Mo₃S₄(H₂O)₅}(H₂AsW₉O₃₃)₂]^10-. X-ray crystal structure analysis of its cesium salt of the composition Cs_5.6K_4.4[{Mo₃S₄(H₂O)₅}(H₂AsW₉O₃₃)₂]·19.15H₂O (1) is reported. Similarly, the reaction of [AsW₉O₃₃]^9- with [W₃S₄(H₂O)₉]⁴⁺ and NaAsO₂ yields [{W₃S₄(H₂O)₅}(H₂AsW₉O₃₃)(HAsW₉O₃₃AsOH)]^9-. For K_6.35(NH₄)_2.65[{W₃S₄(H₂O)₅}(H₂AsW₉O₃₃)(HAsW₉O₃₃AsOH)]·23.7H₂O (2) the crystal structure is determined. In both compounds, the {M₃S₄}⁴⁺ cluster cores coordinate one polyoxometalate ion, which functions as a bridging ligand between two metal atoms, and one bidentate polyoxometalate. The other five coordination sites at the cluster core are occupied by water molecules. The complex anions form dimeric associates held together by hydrogen bonds and S…S contacts.

A method of transfer with an inert carrier gas is used to obtain temperature dependences of pressure vapors. The thermodynamic functions of sublimation processes are calculated for seven molecular crystals that belong to the group of non-steroidal anti-inflammatory drugs: diclofenac, niflumic, flufenamic, tolfenamic, mefenamic, N-phenylanthranilic acids, and diphenylamine. Differential scanning calorimetry is applied to study the melting processes of the selected substances. Single crystal X-ray structural literature data are analyzed, and they are compared with the obtained thermodynamic and thermophysical parameters of sublimation and melting processes. A correlation between the values of the enthalpy of sublimation and the melting temperature under standard conditions is found. The effect of different substituents on the crystal lattice energy of this class of compounds is studied.

The examples of computer experiments on the propagation of wave motion in molecular nanostructures are presented. Some patterns of energy transfer and dissipation inside the molecular structures are discussed.

Simulation of diffraction patterns, radial distribution function analysis, and electron microscopy are applied to study the features of the structure of nanosized pseudoboehmite obtained by the sol-gel method. It is found to consist of plate-like particles with a thickness of one lattice constant in the [010] direction. Such a structure of the pseudoboehmite particles results in the absence of the 020 diffraction peak in the diffraction pattern.

The crystal structures of catechol (o-dihydroxybenzene) and its 2:1 complex with dimethylsulfoxide are determined at T = 150 K. Crystal dat a: C₁₄H₁₈O₅S, M = 298.37, triclinic, space group unit cell parameters: a = 7.7285(13) Е, b = 9.9924(17) Е, c = 10.3188(18) Е, ± = 89.963(4)°, І = 89.968(4)°, і = 69.076(5)°, V = 744.3(2) Е³, Z = 2, D_x = 1.331 g/cm³, R1 = 0.048; C₆H₆O₂, М = 110.11, monoclinic, space group P2₁/n, a = 9.8206(6) Е, b = 5.5903(3) Е, c = 10.4439(6) Е, І = 114.952(2)°; V = 519.85(5) Е³, Z = 4, D_x= 1.407 g/cm³, R1 = 0.0289. In the 2:1 complex the molecules are joined in a supramolecular ensemble by D-H…A hydrogen bonds (D = O, C; A = O, А); in catechol they are bonded only by O-H…O. The state diagram of the catechol-dimethylsulfoxide system is examined by DTA.

The nature and theoretical models of spin crossover equilibrium between high-spin and low-spin forms of transition metal complexes are reviewed. Spin crossover compounds are promising materials for information storage and display devices. In the solid state spin crossover is accompanied by several phenomena related to phase transitions. A critical analysis of theoretical models proposed for the explanation of these phenomena is given. The paper mainly focuses on two models that provide for adequate descriptions of the majority of experimental data, viz. the model of the Ising-like Hamiltonian and the molecular statistical model. Descriptions of spin crossover yielded by these two models are formally similar but not identical and they are based on fundamentally different concepts of molecular interactions and ordering, the latter being the origin of the two-step spin crossover. The Ising-like Hamiltonian model approaches spin crossover fr om the point of view of properties of lattices wh ereas the molecular statistical model explains this phenomenon starting from molecules. The latter approach provides for the elucidation of the molecular nature of cooperative phenomena observed in spin crossover which is important for developing the synthetic strategy of promising spin crossover compounds.

Anharmonic effects are shown to be obtained immediately in the statement of a quantum problem as a general electronic vibrational problem in the matrix formulation and without the use of a traditional anharmonic potential. The methods to form the matrix and to calculate all matrix elements are presented.

The RHF, B3LYP, and PBE0/6-311G** quantum chemical methods are used to determine the point symmetry group and the equilibrium structure of bicyclo[2.2.0]hex-1(4)-ene (I, D_2h), its two stable dimers (tricyclo[4.2.2.2^2,5]dodeca-1.5-diene (II, D_2h) and 2,5-dimethylenetricyclo[4.2.2.0^1,6]decane (III, C₂)), and pentacyclo [4.2.2.2^2,5]dodecane (IV, D₂) that is a hypothetical intermediate in the dimerization reaction of the molecules of I. The relation of total energies is obtained with regard to zero-point vibrations: E(III) < E(II) ? E(IV) ? 2E(I).

The phase of the composition CaBaLaCu₂FeO_7.5 is synthesized from the previously obtained CaCuO₂, La₂Cu₂O₅, and BaFeO₂ double oxides enriched up to 14.7% in ⁵⁷Fe. The phase has the orthorhombic crystal system with the unit cell parameters as follows: a = 0.3882(3) nm, b = 0.3911(3) nm, c = 1.1823(8) nm. Based on the Mössbauer spectra analysis, the conclusion is drawn that iron atoms occupy only Cu(1) sites in the lattice, while more than 90% of them are in the Fe⁴⁺ valence state (80% of these atoms have the tetragonal pyramidal coordination).