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Local crystalline structure of multinary semiconducting alloys : Random vs. ordered distributions

Kisiel A., Robouch B. V., Marcelli A.

Opto-Electronics Review

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2017

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Vol. 25, No. 3

242--250

EN

A description of the status of the art of experimental and theoretical investigations of local crystalline structures of tetrahedron ordered ternary and quaternary semiconducting alloys is presented. Experimental EXAFS data and FTIR analysis are summarized and analyzed using both the Rigid Network Cations theoretical model and the Strained-tetrahedra model. Internal preferences of ion pairs in ternary and qua-ternary alloys are discussed. Several ternary systems of different structures show ideal quasi-canonical Bernoulli distributions, while others are characterized by extreme preferences in which one, several or even all configurations are depressed or even lacking. The results demonstrate that the validity of the Bernoulli distribution is limited and not fulfilled in many systems. This article is an expanded version of the scientific reports presented at the International Conference on Semiconductor Nanostructures for Optoelectronics and Biosensors 2016 ICSeNOB2016, May 22–25, 2016, Rzeszow, Poland.

2

Inter - and inframolecular dynamics of iron porphyrins

Dziedzic-Kocurek K., Okła D., Stanek J.

Nukleonika

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2013

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Vol. 58, No. 1

7-11

EN

The temperature dependent Mössbauer spectroscopy and EXAFS analysis of the dynamical properties of selected iron-porphyrin derivatives: FeTPPCl and FePPIXCl has been presented. It has been shown that these iron-porphyrin properties may be modified by the outer ligands, but they are also strongly influenced by the intermolecular interactions, which are reduced in frozen solutions of the studied complexes.

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Komplementarne zastosowanie metod dyfrakcji i spektroskopii absorpcyjnej promieniowania X do charakteryzacji cienkich warstw Ti-Si-C

Ławniczak-Jabłońska K., Klepka M. T., Wolska A., Dynowska E., Borysiewicz M. A., Piotrowska A.

Elektronika : konstrukcje, technologie, zastosowania

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2012

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Vol. 53, nr 9

28-31

PL

Przedstawiono wyniki komplementarnej charakteryzacji, technikami XRD i XAS, cienkich warstw Ti-Si-C osadzanych metodą wysokotemperaturowego magnetronowego rozpylania katodowego na podłożach szafirowych (00.1) z wykorzystaniem targetów pierwiastkowych Ti, Si i C. Badania dyfrakcyjne wykazały silną zależność składu fazowego warstw od wielkości mocy podawanych na poszczególne targety podczas ich osadzania, natomiast badania spektroskopii absorpcyjnej pozwoliły na określenie zmian w funkcji tej mocy lokalnego, uśrednionego porządku atomowego w otoczeniu atomów Ti i porównanie go z porządkiem jaki powinien występować w modelowym związku Ti₃SiC₂. Wykonano dwie grupy próbek: o relatywnie wysokiej mocy targetu Si i średniej targetu C oraz o względnie niskiej mocy targetu Si i wysokiej targetu C.

EN

This work presents the results of complementary use of XRD and XAS for the characterisation of thin Ti-Si-C films deposited via high temperature magnetron sputtering onto sapphire (00.1) substrates using elemental Ti, Si and C targets. The XRD studies showed a strong dependence of the phase composition of the films on the powers fed to the individual targets during deposition. The XAS studies enabled to determine the local atomic order in Ti neighbourhood and differences in averaged atomic order in function of power fed as compared to a Ti₃SiC₂ model. Two sample sets were fabricated, one with a relatively high power fed to the Si target and a medium power fed to the C target and the second where a relatively low power was fed to the Si target and a high one to the C target.

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Synchrotron microanalytical methods in the study of trace and minor elements in apatite

Rakovan J., Luo Y., Borkiewicz O.

Mineralogia

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2008

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Vol. 39, iss. 1/2

31--40

EN

Synchrotron X-ray facilities have the capability for numerous microanalytical methods with spatial resolutions in the micron to submicron range and sensitivities as low as ppm to ppb. These capabilities are the result of a high X-ray brilliance (many orders of magnitude greater than standard tube and rotating anode sources); a continuous, or white, spectrum through the hard X-ray region; high degrees of X-ray columniation and polarization; and new developments in X-ray focusing methods. The high photon flux and pulsed nature of the source also allow for rapid data collection and high temporal resolution in certain experiments. Of particular interest to geoscientists are X-ray fluorescence microprobes which allow for numerous analytical techniques including X-ray fluorescence (XRF) analysis of trace element concentrations and distributions; X-ray absorption spectroscopy (XAS) for chemical speciation, structural and oxidation state information; X-ray diffraction (XRD) for phase identification; and fluorescence microtomography (CMT) for mapping the internal structure of porous or composite materials as well as elemental distributions (Newville et al. 1999; Sutton et al. 2002; Sutton et al. 2004). We have employed several synchrotron based microanalytical methods including XRF, microEXAFS (Extended X-ray Absorption Fine Structure), microXANES (X-ray Absorption Near Edge Structure) and CMT for the study of minor and trace elements in apatite (and other minerals). We have also been conducting time resolved X-ray diffraction to study nucleation of and phase transformations among precursor phases in the formation of apatite from solution at earth surface conditions. Summaries of these studies are given to exemplify the capabilities of synchrotron microanalytical techniques.

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EXAFS study of iron nanoparticles with oxide shell

Onyszko A., Kapusta C., Sieniawski J.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 10

597-600

EN

Purpose: The aim of this work is to present the results of the study of the local structure of iron nanoparticles with oxide shell which uses EXAFS method that apply synchrotronic radiation. Design/methodology/approach: The samples used in the carried out analysis were as follows: pure iron powder, pure iron powder containing nanoparticles and pure iron powder containing nanoparticles subjected to 224 hours of grinding. Findings: The local structure of iron nanoparticles with oxide shell were found. Research limitations/implications: It wa s not enough time to measure O:K edge. Practical implications: The analysis of spectra does not reveal any iron oxides in samples. More accurate results would be obtained at oxygen K edge. Originality/value: It was proved that iron nanoparticles with oxide shell samples had the local structure characteristic for metallic iron.

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EXAFS/XANES studies of the local structure of amorphous ionic and electronic-ionic conductors

Wasiucionek M., Garbarczyk J., Bacewicz P., Jóźwiak J, Nowiński J.L.

Materials Science Poland

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2006

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Vol. 24, No. 1

181--186

EN

X-ray absorption spectroscopy methods such as EXAFS (Extended X-ray Absorption Fine Structure) and XANES (X-ray Absorption Near Edge Structure) are sophisticated and effective tools for studying the local structure of many solids and liquids. Their use is particularly valuable in the case of amorphous systems, in which due to the absence of long-range order the possibilities of structure determination by diffraction methods are limited. EXAFS and XANES have been extensively used to study the local structure of many electrically conducting (via ions, electrons, or both electrons and ions) solids. The special merit of the latter studies is that their results reveal the short-range structure of these conductors, which is an important factor determining their transport properties. The paper reports recent results of EXAFS/XANES studies on the local structure of selected electrically conducting glasses of the Li2O-V2O5-P2O5 system and their silver analogues. All spectra were acquired at the K-edge of vana

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EXAFS study of glasses of the CaO-Ga2O3-GeO2 system

Chełstowski D., Witkowska A., Rybicki J., Padlyak B., Trapananti A., Principi E.

Optica Applicata

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2003

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Vol. 33, nr 1

125-132

EN

X-ray absorption spectroscopy (XAS) measurements for Ca3Ga2Ge3O12 and Ca3Ga2Ge4O14 glasses are presented. In particular, the extended X-ray absorption fine structure (EXAFS) spectra are analysed and local neighbourhood of Ga and Ge atoms is described in detail. The Ge/Ga atoms neighbourhood in considered glasses is compared with the data available for corresponding crystals. Performed comparative crystal-glass structural analysis confirms correlation between crystalline and glassy structures of the Ca3Ga2Ge3O12 and Ca3Ga2Ge4O14 compounds. Our results provide several new detailed data, and some general suggestions on the CaO–Ga2O3–GeO2 glass structure.

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Crystal Structure, EXAFS Study and Low Temperature Magnetic Properties of Ammonium Hexabromorhenate

Mroziński J., Tomkiewicz A., Hartl H., Brüdgam I., Villain F.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 2-3

285-293

EN

Crystal and molecular structures of ammonium hexabromorhenate (NH4)2ReBr6 have been determined by the heavy atom method. The title compound crystallizes red-violet crystals in the space group Fm3m with Z = 4. The Re atom is of six-coordinate octahedral configuration, being bonded to six bromide anions. The magnetic behaviour of (NH4)2ReBr6 has been investigated over the temperature range 1.72-300 K. These measurements revealed that this compound is an antiferromagnet with Neél temperature TN = 15.5 K. The magnetic data are interpreted in terms of zero-field splitting of the ground 4A2g term (D = 22.8 cm-1), large because of the high spin-orbit coupling constant for the Re+4 ion, with antiferromagnetic exchange coupling (J = -17.7 cm-1).

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Electronic and magnetic dynamic properties of imidazolate complexes

Ragot F., Belin S., Ivanov V. G., Perry D. L., Ortega M., Ignatova T. V., Kolobov I. G., Masalitin E. A., Kamarchuk G. V., Yeremenko A. V., Molinié P., Wéry J., Faulques E.

Materials Science

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2002

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Vol. 20, No. 3

11-27

EN

Transition-metal complexes of imidazole ImH (C3H4N2) are relevant for the study of metalloenzymes and protein folding. Moreover, these materials could lead to potential applications such as electrochromic displays, photovoltaic cells and biomaterials. A series of metal-imidazole complexes of general formula + - x Mx Im (where x = 1, 2, M = Ag, Zn, Co, Cu and Im- = C3H3N2 is the deprotonated form of ImH) was synthesized and comprehensively studied as model materials for metalloproteins and molecular magnets. Their atomic dynamic properties were investigated with X-ray diffraction, XANES, EXAFS, vibrational spectroscopy and magnetic techniques. Metal-ligand bond lengths and force constans were estimated. The relationship between these structural data and rich spin dynamics revealed for M = Cu, Co bis-imidazolate compounds is discussed.

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GNXAS: a software package for advanced EXAFS multiple-scattering calculations and data-analysis

Filipponi A., Di Cicco A.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2000

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Vol. 4, No 4

575-669

EN

Computational and theoretical advances for the interpretation of the X-ray absorption spectroscopy (XAS) cross-section, and associated extended X-ray absorption fine structure (EXAFS) are the basis of an advanced software package for EXAFS data analysis, called GNXAS. This software package is composed of a series of FORTRAN programs for EXAFS data-analysis (including the main codes crymol, phagen, gnpeak, gnxas, and fitheo) together with several utility programs for sample optimization, automatic background subtraction, and edge analysis. The GNXAS package allows scientists to perform accurate multiple-scattering EXAFS calculations of the XAS cross-section achieving a reliable refinement of the structural models in the short-range. These characteristics are useful for taking full advantage of the high data quality obtained at modern synchrotron radiation facilities. The philosophy, methodology, and practical usage aspects of the main data-analysis codes are described in detail. The procedures for the estimation of statistical errors and for the data analysis of liquids and highly disordered systems are also discussed. A useful list of references on the development of the method and applications to various scientific fields is included. The content of the paper can be regarded as a full documentation and guide for proper usage of the current version of the GNXAS software.