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Structural properties of Mn-substituted hercynite

Abstract

In this work spinel series with the general formula Fe1-xMnxAl2O4 (where x = 0, 0.3, 0.5 and 0.7) were synthesized and characterized with respect to their structure and microstructure. X-ray diffractometry (XRD) was used to identify the phase composition that revealed a single phase spinel material. Rietveld refinements of the XRD patterns were carried out in order to determine the lattice and oxygen positional parameters of the spinel compounds. Mössbauer effect measurements were performed at room temperature to determine the local chemical environment of the Fe ions, their valences, and degrees of spinels inversion. It was shown that an increase in the Mn content led to a decrease in the ratio of Fe2+ to Fe3+. The results obtained from Mössbauer spectroscopy (MS) were used to establish the chemical formulas of the synthesized spinels. Finally, the microstructure that was observed using scanning electron microscopy (SEM) showed a compact microstructure with an octahedral crystal habit.

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Magnetic and structural properties of Sc(Fe1−xSix)2 Laves phases studied by Mössbauer spectroscopy and neutron diffraction

Abstract

The aim of the presented paper is to study an influence of replacement of Fe atoms by Si atoms in quasibinary Sc(Fe1− xSix)2 Laves phases on their structural and magnetic properties. Powder X-ray diffraction (XRD) and neutron diffraction (ND) measurements carried out at different temperatures from 4.3 K up to about 700 K revealed that samples were single phase with cubic C15 structure for Si concentration x from 0.05 to 0.20 and hexagonal C14 structure for higher concentration. The results of 57Fe Mössbauer measurements showed that the Sc(Fe1− xSix)2 compounds with x ≤ 0.30 are ferrimagnetic at 4.3 K. At temperature 80 K in the samples with x = 0.20 and 0.30, a magnetic cluster spin-glass state has been observed, as ferrimagnetic long-range order disappears. Such picture was supported by the results of ND measurements carried out at 8 K, which confirmed the lack of long-range order for x above 0.10 and an occurrence of hyperfine field distributions in the corresponding Mössbauer spectra. At room temperature, samples with x ≥ 0.20 became paramagnetic. A substitution of Si atoms for Fe ones leads to a decreasing of mean values of hyperfine magnetic fields in samples under investigation. From the neutron diffraction pattern analysis of Sc(Fe0.90Si0.10)2Fe magnetic moment was determined as to be equal to 1.5 μB at 8 K. Combining this result with a value of hyperfine magnetic field on 57Fe probes, the hyperfine coupling constant A in Sc(Fe0.90Cu0.10)2 phases is estimated at about 11.6 T/μB at 8 K.

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A Structural Model of Reconstituted Tobacco Substantiated by Ultrasonic Interrogation

Abstract

The theoretical model and experimental results, as tabulated in Table 1, lead to the following conclusions concerning the elastic and structural properties of the examined reconstituted tobaccos:

The vehicle of ultrasonic interrogation of reconstituted materials proved to be efficacious. In total, the authors observed the advantages of this mode of experimentation to be:

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Atomic short-range order in mechanically synthesized iron based Fe-Zn alloys studied by 57Fe Mössbauer spectroscopy

Abstract

Mechanical alloying method was applied to prepare nanocrystalline iron-based Fe1− xZnx solid solutions with x in the range 0.01 ≤ x ≤ 0.05. The structural properties of the materials were investigated with the Mössbauer spectroscopy by measuring the room temperature spectra of 57Fe for as-obtained and annealed samples. The spectra were analyzed in terms of parameters of their components related to unlike surroundings of the iron probes, determined by different numbers of zinc atoms existing in the neighborhood of iron atoms. The obtained results gave clear evidence that after annealing process, the distribution of impurity atoms in the first coordination spheres of 57Fe nuclei is not random and it cannot be described by binomial distribution. The estimated, positive values of the short-range order parameters suggest clustering tendencies of Zn atoms in the Fe-Zn alloys with low zinc concentration. The results were compared with corresponding data derived from Calphad calculation and resulting from the cellular atomic model of alloys by Miedema.

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Mössbauer spectroscopy study of 60P2O5-40Fe2O3 glass crystallization

glass. Nukleonika , 58 (1), 63–66. 9. Stoch, P., Szczerba, W., Bodnar, W., Ciecińska, M., Stoch, A., & Burkel, E. (2014). Structural properties of iron-phosphate glasses: spectroscopic studies and ab initio simulations. Phys. Chem. Chem. Phys ., 16 , 19917–19927. DOI: 10.1039/C4CP03113J. 10. Millet, J. M., Verley, C., Forissier, M., Bussiere, P., & Verdine, J. C. (1989). Mössbauer spectroscopic study of iron phosphate catalysts used in selective oxidation. Hyperfine Interact ., 46 (1), 619–628. DOI: 10.1007/BF02398251. 11. Khan, F. B., Bharuth-Ram, K

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The influence of air conditioning changes on the effective dose due to radon and its short-lived decay products

. Grządziel D. Stawarz O. Wysocka M. Dorda J. Żebrowski A. Olszewski J. Hovhannisyan H. Dohojda M. Kapała J. Chmielewska I. Kłos B. Jankowski J. Mnich S. Kołodziej R. 2011 Correction factors for determination of annual average radon concentration in dwellings of Poland resulting from seasonal variability of indoor radon Appl. Radiat. Isot. 69 1459 1465 3. Somlai, J., Jobbágy, V., Kovács, J., Németh, Cs., & Kovács, T. (2008). Connection between radon emanation and some structural properties of coal-slag as building material

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Iron-containing phases in metallurgical and coke dusts as well as in bog iron ore

-39. DOI: dx.doi.org/10.4314/ijest.v2i8.63778. 19. Haley, G., Mullen, J. G., & Honigt, J. M. (1989). First order change in hyperfi ne interaction at the Verwey transition in magnetite. Solid State Commun., 69(3), 285-287. DOI: 10.1016/0038-1098(89)90852-1. 20. Lee, S. W., Kim, S. J., & Kim, Ch. S. (2006). Superexchange interactions in MgFe2O4. J. Korean Phys. Soc., 48(4), 583-588. 21. Omer, M. I. M., Elbadawi, A. A., & Yassin, O. A. (2013). Synthesis and structural properties of MgFe2O4 ferrite nano-particles. JAIS-J. Appl

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Computing topological indices of the line graphs of Banana tree graph and Firecracker graph

mathematical approach Journal of Mathematical Chemistry 52 4 1059 1065 10.1007/s10910-013-0285-x [6] N. Cohen, D. Dimitrov, R. Krakovski, R. Škrekovski and V. Vukašinović, (2010), On Wiener Index of Graphs and Their Line Graphs , MATCH Communications in Mathematical and in Computer Chemistry, 64, No 3, 683-698. Cohen N. Dimitrov D. Krakovski R. Škrekovski R. Vukašinović V. 2010 On Wiener Index of Graphs and Their Line Graphs MATCH Communications in Mathematical and in Computer Chemistry 64 3 683 698 [7] D. Dimitrov, (2016), On structural properties of trees with

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Revan and hyper-Revan indices of Octahedral and icosahedral networks

large number of topological indices which are classified based on the structural properties of the graphs used for their calculations. In general, they are classified into distance-based topological indices, degree-based topological indices and counting related indices of graphs. The degree-based topological indices, which have reliable predicting power and thus they have been employed in deriving multi-linear regression models for statistical correlation of properties. The topological indices such as atom-bond connectivity and geometric-arithmetic are also used to

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The Composition of Cigarette Smoke: A Catalogue of the Polycyclic Aromatic Hydrocarbons

similarity based on notation similarity; J. Math. Chem. 2 (1988) 155–169; Herndon, W.C., P.C. Nowak, D.A. Connor, and P. Lin; Empirical model calculations for thermodynamic and structural pro-perties of condensed polycyclic aromatic hydrocarbons; J. Am. Chem. Soc. 114 (1992) 41–47; Herndon, W.C. and L.V. Szentpaly: Theoretical model of activation of carcinogenic polycyclic benzenoid aromatic hydro-carbons. Possible new classes of carcinogenic aromatic hydrocarbons; J. Molecul. Structure (Theochem) 148 (1986) 141–152; Structure-property relationships in polycyclic aromatics

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