I. N. Shabanova

XPS-studies of the electronic structure of Fe–X (X=Al, Si, P, Ge, Sn) systems

Abstract For the stoichiometric compounds FeSi, FeGe, FeSn, FeAl, and FeP the X-ray photoelectron spectra of valence bands are obtained and the calculations of their electronic structure are carried out by the full-potential linear muffin–tin–orbital method (FP-LMTO) and by the tight-binding linear muffin–tin–orbital atomic sphere-approximation method (TB-LMTO-ASA). A satisfactory agreement of the X-ray photoelectron spectra and the calculated density of states curves is obtained. The comparison of the experimental spectra with the calculated curves shows that if the second component (X) of an alloy belongs to the same (IVth) group of the periodic table, the p–d hybridization is maximum in the alloy FeSi and decreased with the increase in the atomic radius (atomic number) of X(Ge, Sn). If X belongs to the same (IIIrd) row of the periodic table, then the p–d hybridization is maximum in FeAl and decreased with the increase in the number of p electrons of X(Si, P).

Application of X-ray photoelectron spectroscopy for studying the molecular structure of corrosion inhibitor — Zinc complex of 1-hydroxyethylidene diphosphonic acid

The molecular structure of zinc complex of 1-hydroxyethylidene diphosphonic acid was studied by X-ray photoelectron spectroscopy. The obtained data were compared with IR absorption spectrum of the same substance to acquire new information on the molecular structure. It was shown that coordination of the phosphonate group by zinc atom retains the localization of P-O π bond, the phosphonate group does not have a third-order axis of symmetry, and Zn atom can occupy positions with different coordination. Thermal destruction of the complex is accompanied by decomposition of hetero-organic ligand with detachment of the hydrocarbon fragment along C-P bonds and formation of inorganic zinc salts.

Interaction between ZnHEDP corrosion inhibitor and a surface of carbon steel

The interaction between the metal-complex corrosion inhibitor ZnHEDP (a zinc complex with 1-hydroxy-ethylidene-diphosphonic acid) and a surface of 20kp steel is studied. It is shown that the chemical interaction between the corrosion inhibitor and the steel surface leads to the formation of a strong covalent bond of Zn-O-P-Fe atoms, and to Fe atoms transitioning into a high-spin state. Thermal action on the protective film results in the breaking of C-P bonds and the detachment of a carbon-containing fragment. At temperatures above 525 K, the Zn-O-(P-O)-Fe complex breaks down.

Electronic structure of crystalline FeSi and FeGe

X-Ray photoelectron valence band spectra were recorded for stoichiometric compounds FeSi and FeGe; their electronic structure was calculated by the ab initio full-potential linear muffintin orbital method. For nonmagnetic FeSi, good agreement was obtained between the calculated densities of states and the X-ray photoelectron spectrum in both peak positions and forbidden gap. For FeGe, which is an antiferromagnet, the nonmagnetic calculation yields worse agreement with experiment and explicitly indicates that the paramagnetic phase is unstable. In both compounds, the calculation gives a high degree of d—p hybridization and covalence, which is estimated quantitatively. In FeGe, the degree of covalence of the Fe-Fe bond is higher than that of the Fe-Ge bond.

The trisodium monohydrogen-nitrilo-tris-methylenephosphonato-hydroxylaminato-nitrosyl-molybdate octahydrate Na3[Mo(NO)(NH2O){N(CH2PO3)3H}] · 8H2O: Synthesis, structure, and nature of coordination bond of transition metal with non-innocent ligand

The sodium salt of heteroleptic molybdenum complex with nitrilotris(methylenephosphonic) acid (NTP), hydroxylamine, and nitrogen(II) oxide Na3[Mo(NO)(NH2O){N(CH2PO3)3H}]· 8H2O was synthesized, isolated, and studied (space group P21/c, Z = 4, a = 9.7385(2), b = 10.2542(2), c =21.6517(3) Å, β = 93.7060(10)°). The nitrilotris(methylenephosphonate) ion is monoprotonated at the PO3 group. The nitrogen atom is deprotonated and coordinates the Mo atom; the NTP denticity is 4. Hydroxylamine is ionized according to the acid type and is bidentate. The Mo–NO group is almost linear (176.31(19)° angle; Mo–N, 1.7599(13) Å; ν(N–O), 1756 cm–1), the electron density distribution attests to the formation of an Mo–N π-bond. The Mo coordination polyhedron is a distorted pentagonal bipyramid. Two Na ions are coordinated at the vertices of a distorted octahedron and the third one forms a distorted tetrahedral geometry. (CIF file CCDC no. 1543700.)

Synthesis and structure of tetrasodium nitrilotrismethylenephosphonato zincate tridecahydrate Na4[ZnN(CH2PO3)3]·13H2O, a corrosion inhibitor

Organophosphonate zincate corrosion inhibitor (CCDC 919565) contains the Zn-N bond closing three fivemembered chelate rings with the formation of a common bonding electronic subsystem of N-Zn-O-P atoms. Zinc is coordinated in a distorted trigonal bipyramidal configuration involving the oxygen atom of the neighboring molecule of the complex. Space group

Investigation of the electronic structure of the Fe-Si systems by x-ray photoelectron spectroscopy

P\bar 1

Dihydronitrilotris(methylenephosphonato)dimercury(II)mercury(I) [(Hg 2 I )Hg II N(CH 2 PO 3 ) 3 H 2 ]: Synthesis and Structure

, Z = 2, a = 11.2208(2) Å, b = 11.2666(3) Å, c = 12.3286(3) Å, α = 108.455(2)°, β = 97.168(2)°, γ = 117.103(2)°. The inhibitor does not form polymeric structures, provides the stability and reproducibility of technological quality parameters. The initial decomposition temperature is 250 °C. The corrosion inhibition factor is 14.3 (GOST 9.502-82, steel grade 20, medium No. 2, static conditions, natural aeration, 10 days exposure).