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Wyświetlanie 1-11 z 11
Tytuł:
Extended X-Ray Absorption Fine Structure Studies of Co Doped ZnS and ZnSe Alloys
Autorzy:
Ławniczak-Jabłońska, K.
Gołacki, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1931712.pdf
Data publikacji:
1994-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.10.Lx
78.70.Dm
87.64.Fb
Opis:
X-ray absorption experiments were performed at the Kedge of Co and Zn in Zn$\text{}_{1-x}$Co$\text{}_{x}$S and Zn$\text{}_{1-n}$Co$\text{}_{x}$Se compounds with x = 0.25, 0.16, 0.10, 0.05, 0.00 in the sulphides samples and x = 0.07, 0.02, 0.00 in the selenide ones. Analysis of the extended X-ray absorption fine structure oscillations using phase and amplitudes either from McKale code or from standard samples, gave the distance, number of atoms and the Debye-Waller factors for nearest neighbours. We found that the cation-anion distances Zn-S(Se) or Co-S(Se) are systematically shorter in ZnS than in ZnSe matrix, the Zn-anion distance is always larger than the Co-anion one without any significant Co content dependence. This allowed us to estimate the covalent radius of Co in the studied matrices to be 0.025 Å smaller than the Zn covalent radius and stated that covalent radius of Co is independent of the type of surrounding atoms. In addition the Debye-Waller factors indicated a better ordering in ternary compounds than in the binary standard ones in agreement with rocking curve measurements.
Źródło:
Acta Physica Polonica A; 1994, 86, 5; 727-735
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EXAFS Determination of Bond Lengths in Zn$\text{}_{1-x}$Fe$\text{}_{x}$S Ternary Alloys
Autorzy:
Iwanowski, R. J.
Ławniczak-Jabłońska, K.
Powiązania:
https://bibliotekanauki.pl/articles/1963384.pdf
Data publikacji:
1997-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Dm
Opis:
Studies of local atomic structure in the zinc-blende Zn$\text{}_{1-x}$Fe$\text{}_{x}$S (x=0.11-0.50) diluted magnetic semiconductors with the use of the EXAFS technique are reported for the first time. They include the K-edge EXAFS measurements for both cationic elements (Zn, Fe). The experiment was carried out at room temperature in the transmission mode using synchrotron radiation of the DCI storage ring in Orsay, France. A detailed EXAFS analysis for different crystal compositions (x) gave a convincing evidence for a bimodal distribution of the nearest-neighbour interatomic distances in Zn$\text{}_{1-x}$Fe$\text{}_{x}$S within the iron solid-solubility limit. It has also revealed, within the accuracy of this method, constancy of both the nearest-neighbour cation-anion distances (i.e. Zn-S and Fe-S) in the composition range studied.
Źródło:
Acta Physica Polonica A; 1997, 91, 4; 797-801
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chemical Shifts at K-Absorption Edges of Transition Metals Admixed To ZnS and ZnSe
Autorzy:
Iwanowski, R. J.
Ławniczak-Jabłońska, K.
Traverse, A.
Powiązania:
https://bibliotekanauki.pl/articles/1963385.pdf
Data publikacji:
1997-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Dm
Opis:
This paper gives the experimental evidence of systematic X-ray K-absorption edge studies in an effort to analyse the effect of cation chemical shift in the group of compounds type Zn$\text{}_{1-x}$M$\text{}_{x}$A (M = Mn, Fe, Co, Ni; A = S, Se). The observed chemical shift was found practically independent of the choice of anion, whereas it revealed a noticeable decrease when passing from Mn to Zn. The effect was ascribed to the change of the 3d shell occupation. The calculations of the effective cation charge (based on the theoretical approach of Kitamura and Chen, 1991) have shown that in the case of transition metals admixed to ZnS and ZnSe there is a contribution of the 3d electrons to the overall charge transfer, which indicates that the ability of 3d electrons to participate in predominantly ionic bond decreases with 3d orbit filling.
Źródło:
Acta Physica Polonica A; 1997, 91, 4; 803-808
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of Mo-Ni Alloys by X-Ray Spectroscopies
Autorzy:
Ławniczak-Jabłońska, K.
Heinonen, M.
Inoue, J.
Tohyama, T.
Powiązania:
https://bibliotekanauki.pl/articles/1924333.pdf
Data publikacji:
1993-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Cf
78.70.En
79.60.-i
Opis:
Band structure investigations of the random MoNi$\text{}_{4}$ and MoNi$\text{}_{3}$ alloys, performed by emission and photoelectron spectroscopy, is reported. The X-ray emission and X-ray photoelectron spectra allowed to study the occupied valence band states below Fermi level. These techniques gave the full description of changes in the density of valence electron states distribution due to substitution of Mo atoms into the fcc Ni lattice up to 25 at%. The analysis of the emission and photoelectron spectra led to clear distinction between the changes in spectra caused by density of states structure and by additional effects involved in creation of the particular spectra. The experimental data are compared with the density of states calculated using coherent potential approximation and linear muffin-tin orbital methods.
Źródło:
Acta Physica Polonica A; 1993, 83, 1; 115-124
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lattice Site Occupancy in Ternary Ordered Ni$\text{}_{3}$Al$\text{}_{1-x}$Fe$\text{}_{x}$ Alloys Estimated by EXAFS
Autorzy:
Ławniczak-Jabłońska, K.
Pascarelli, S.
Boscherini, F.
Kozubski, R.
Powiązania:
https://bibliotekanauki.pl/articles/1920905.pdf
Data publikacji:
1992-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.10.Lx
61.55.Hg
Opis:
Extended X-ray absorption fine structure (EXAFS) spectroscopy offers additional experimental evidence to the solution of site occupancy problem in ternary NiAlX alloys. A study of local order in the stoichiometric Ni$\text{}_{3}$Al$\text{}_{1-x}$Fe$\text{}_{x}$ ternary alloys (x = 0.02, 0.05, 0.10, 0.15, and 0.25) by EXAFS at the K-edge of Fe in the energy range from 7000 eV to 7600 eV are presented. Three models of substitutional behavior are considered - the preferential substitution of Fe atoms in: 1) Ni sites, 2) Al sites, 3) both sites. Data analysis was performed with theoretical and experimentally determined scattered photoelectron phases and amplitudes. The results of the EXAFS analysis are consistent with the picture in which most of the Fe atoms substitute Al sites and less than 25% of Fe atoms substitute Ni sites. Alloys with more than 10 at% of Fe showed higher tendency for ordering than those containing less than 10 at% Fe.
Źródło:
Acta Physica Polonica A; 1992, 82, 2; 315-322
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Poznawanie własności materii w skali atomowej za pomocą absorpcji promieniowania synchrotronowego
Autorzy:
Drzewiecka, A.
Wolska, A.
Klepka, M. T.
Ławniczak-Jabłońska, K.
Powiązania:
https://bibliotekanauki.pl/articles/274182.pdf
Data publikacji:
2012
Wydawca:
Roble
Tematy:
promieniowanie synchrotronowe
rentgenowska spektroskopia absorpcyjna
synchrotron radiation
X-ray absorption spectroscopy
Źródło:
LAB Laboratoria, Aparatura, Badania; 2012, 17, 6; 16-21
1427-5619
Pojawia się w:
LAB Laboratoria, Aparatura, Badania
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The complementary structural studies of the double metal cyanide type catalysts for the ring opening polymerization of the oxiranes
Komplementarne badania strukturalne dimetalocyjankowych katalizatorów polimeryzacji z otwarciem pierścienia oksiranowego
Autorzy:
Chruściel, A.
Hreczuch, W.
Czaja, K.
Ławniczak-Jabłońska, K.
Janik, J.
Powiązania:
https://bibliotekanauki.pl/articles/947469.pdf
Data publikacji:
2016
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
Tematy:
double metal cyanide catalysts (DMC)
thermal analysis
thermogravimetric analysis (TG)
differential scanning calorimetry (DSC)
evolved gas analysis (EGA)
X-ray absorption spectroscopy (XAS)
X-ray absorption near edge structure (XANES)
extended X-ray absorption fine structure (EXAFS)
katalizatory dimetalocyjankowe (DMC)
analiza termiczna
analiza termograwimetryczna (TGA)
różnicowa kalorymetria skaningowa (DSC)
analiza wydzielanych gazów (EGA)
rentgenowska absorpcyjna spektroskopia struktury przykrawędziowej (XANES)
synchrotronowa absorpcyjna spektroskopia rentgenowska (EXAFS)
Opis:
The extensive complementary experimental studies of the double metal catalysts (DMC) with two kinds of the organic ligands were performed. The chemical justification of the observed TG/DSC (thermogravimetric analysis/differential scanning calorimetry) steps was proposed. Several organic ligand complexing states were found in both types of catalysts. X-ray absorption spectroscopy (XAS) analysis established that only Zn atoms are the active metallic centers in DMC catalyst regardless the used ligand. Cl atoms were detected near some of Zn atoms. Contrary to the common suppositions no significant amount of oxygen atoms was detected in the closest coordination spheres of Zn.
Przeprowadzono badania strukturalne katalizatorów dimetalocyjankowych (DMC) z dwoma rodzajami ligandów organicznych. Zaproponowano wyjaśnienie etapów przebiegu krzywych otrzymanych metodą analizy termograwimetrycznej i różnicowej kalorymetrii skaningowej (TG/DSC) badanych katalizatorów. Wykazano obecność kilku stopni związania ligandów w kompleksach DMC. Na podstawie wyników badań z wykorzystaniem absorpcji rentgenowskiej (XAS) stwierdzono, że centrum aktywne katalizatora stanowi atom cynku. W bezpośrednim sąsiedztwie atomów Zn wykryto obecność atomów Cl, natomiast w najbliższych sferach koordynacyjnych atomu Zn nie wykryto atomów tlenu.
Źródło:
Polimery; 2016, 61, 6; 421-432
0032-2725
Pojawia się w:
Polimery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of the Local Environment of Mn Ions Implanted in GaSb
Autorzy:
Wolska, A.
Lawniczak-Jablonska, K.
Klepka, M.
Barcz, A.
Hallen, A.
Arvanitis, D.
Powiązania:
https://bibliotekanauki.pl/articles/1538865.pdf
Data publikacji:
2010-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Dm
61.72.U-
61.05.cj
Opis:
The first attempts to establish an implantation process leading to formation of ferromagnetic inclusions inside the GaSb matrix are presented. Gallium antimonide containing ferromagnetic MnSb precipitations is considered as a promising material for novel spintronic applications. It is possible to obtain such inclusions during the molecular beam epitaxy (MBE) growth. However, for commercial application it would be also important to find an optimal way of producing this kind of inclusions by Mn ions implantation. In order to achieve this goal, several parameters of implantation and post annealing procedures were tested. The ion energy was kept at 10 keV or 150 keV and four different ion doses were applied, as well as various annealing conditions. The analysis of X-ray absorption spectra allowed to estimate the local atomic order around Mn atoms. Depending on the implantation energy and annealing processes, the manganese oxides or manganese atoms located in a heavily defected GaSb matrix were observed. The performed analysis helped in indicating the main obstacles in formation of MnSb inclusions inside the GaSb matrix by Mn ion implantation.
Źródło:
Acta Physica Polonica A; 2010, 117, 2; 286-292
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
X-Ray Photoelectron Spectroscopy and X-Ray Diffraction Studies of Zn$\text{}_{1-x}$Co$\text{}_{x}$S Diluted Magnetic Semiconductor Crystals
Autorzy:
Ławniczak-Jabłońska, K.
Gołacki, Z.
Paszkowicz, W.
Iwanowski, R. J.
Johansson, L.-S.
Heinonen, M.
Powiązania:
https://bibliotekanauki.pl/articles/1861485.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.60.-i
71.20.Fi
Opis:
X-ray photoelectron spectroscopy and powder X-ray diffraction studies of diluted magnetic semiconducting alloys Zn_{1-x}Co_{x}S, in the composition range 0 ≤ x ≤ 0.18, were performed. The analysis of XPS spectra has shown that admixture of Co into ZnS lattice does not affect the shape and position of Zn 2p core level, whereas certain modification of the S 2p peak shape was observed. The detected binding energy of Co indicated similarity between Co-S and Co-O bond structure. Significant contributions of Co 3d^{7} electrons to the valence band density of states were revealed.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 633-636
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
X-Ray Absorption Studies of Ge Layers Buried in Silicon Crystal
Autorzy:
Demchenko, I. N.
Ławniczak-Jabłońska, K.
Zhuravlev, K. S.
Piskorska, E.
Nikiforov, A. I.
Welter, E.
Powiązania:
https://bibliotekanauki.pl/articles/2030656.pdf
Data publikacji:
2002-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ey
78.70.Dm
81.05.Gc
Opis:
Polarization-dependent X-ray absorption spectroscopy was used to study the local microstructure of Ge layers buried in silicon. The layers with thickness from 6 to 20 monolayers of Ge were grown by molecular beam epitaxy on Si substrate and were covered by Si (20 nm). To investigate the morphology of grown structures, X-ray absorption near edge structure and extended X-ray absorption fine structure analysis of the Ge K-edge was done. The performed qualitative analysis proves that X-ray absorption spectra are very sensitive to the local order in the formed structures and are sources of unique information about morphology of the buried Ge layers. Using these techniques we were able to observe the changes in atomic order around the Ge atoms in investigated buried layers and compare the formed atomic order with that in crystalline Ge. A substantial increase in intensity, broadening and chemical shift of the X-ray absorption near edge structure spectrum for 8 ML were observed. It can be related to the increase in density of electron states caused by increase in the localization of the states due to potential appearing at the Ge island boundaries and indicated the formation of quantum dots. The observed in-plane modulations of radial distribution and out-of-plane for different layers were discussed.
Źródło:
Acta Physica Polonica A; 2002, 101, 5; 709-717
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
XANES Studies of Mn K and $L_{3,2}$ Edges in the (Ga,Mn)As Layers Modified, by High Temperature Annealing
Autorzy:
Wolska, A.
Lawniczak-Jablonska, K.
Klepka, M.
Jakieła, R.
Demchenko, I.
Sadowski, J.
Holub-Krappe, E.
Persson, A.
Arvanitis, D.
Powiązania:
https://bibliotekanauki.pl/articles/1812244.pdf
Data publikacji:
2008-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Dm
75.50.Pp
Opis:
$Ga_{1-x}Mn_xAs$ is commonly considered as a promising material for microelectronic applications utilizing the electron spin. One of the ways that allow increasing the Curie temperature above room temperature is to produce second phase inclusions. In this paper $Ga_{1-x}Mn_xAs$ samples containing precipitations of ferromagnetic MnAs are under consideration. We focus on the atomic and electronic structure around the Mn atoms relating to the cluster formation. The changes in the electronic structure of the Mn, Ga and As atoms in the (Ga,Mn)As layers after high temperature annealing were determined by X-ray absorption near edge spectroscopy. The experimental spectra were compared with the predictions of ab initio full multiple scattering theory using the FEFF 8.4 code. The nominal concentration of the Mn atoms in the investigated samples was 6% and 8%. We do not observe changes in the electronic structure of Ga and As introduced by the presence of the Mn atoms. We find, in contrast, considerable changes in the electronic structure around the Mn atoms. Moreover, for the first time it was possible to indicate the preferred interstitial positions of the Mn atoms.
Źródło:
Acta Physica Polonica A; 2008, 114, 2; 357-366
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-11 z 11

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