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1.
F. D. Saccone C. E. Rodrí guez Torres F. H. S nchez O. Gutfleisch 《Physica B: Condensed Matter》2002,320(1-4):312-315
In the present work, a quantitative analysis of the phase compositions by Mössbauer effect spectroscopy of solid and conventional hydrogen disproportionated Pr13.7Fe80.3B6.0 and Pr13.7Fe63.5Co16.7Zr0.1B6.0 alloys was carried out. Significant amounts of intermediate borides t-Fe3B and Pr(Fe, Co)12B6 were detected after solid hydrogen disproportionation treatment in Pr13.7Fe80.3B6.0 and Pr13.7Fe63.5Co16.7Zr0.1B6.0 alloys, respectively. After conventional hydrogenation–disproportionation–desorption–recombination treatment these phases were not detected and in no case residual Pr2Fe14B-phase was found. It was observed that the amount of intermediate borides after disproportionation can be correlated with the degree of texture after recombination at various temperatures. 相似文献
2.
F. H. Sánchez C. Rodríguez Torres F. D. Saccone Alejandro Ayala 《Hyperfine Interactions》2001,133(1-4):33-40
In this work a practical method of fitting complex multiphase Mössbauer effect spectra is proposed. The task is simplified imposing specific restrictions to the analysing functions, which are appropriate for cases where the component phases spectra do not change substantially during the process under study. The ME spectra can be analysed using the phases subspectra, by defining only a reduced number of parameters. The constraints are equivalent to assume a Doppler velocity transformation v=(v–m)B
m0/B
m+m0 for each phase, where m and B
m are fitting parameters containing information on the phase mean isomer shift and hyperfine field and m0 and B
m0 their reference values. In this manner physically meaningful results are easy to obtain. The idea was applied to partially nitrogenated R2Fe17N
x
(R= Sm and Y) and partially hydrogen-decomposed Nd–Fe–B materials. 相似文献
3.
Pavlo Solokha Serena De Negri Bernhard Eck Adriana Saccone 《Journal of solid state chemistry》2010,183(12):2995-3001
The crystal structures of two new ternary phases, La4Ag10Mg3 and La4Ag10.3Mg12, were refined from X-ray single crystal diffraction data. La4Ag10Mg3 crystallizes in the Ca4Au10In3 structure type, an ordered variant of the binary Zr7Ni10 compound: orthorhombic, Cmce, oS68, a=14.173(5), b=10.266(3), c=10.354(3) Å, Z=4, wR2=0.0826, 676 F2 values, 50 variables. La4Ag10.3Mg12 represents a new structure type: orthorhombic, Cmmm, oS116-10.32, a=9.6130(3), b=24.9663(8), c=9.6333(2) Å, Z=4, wR2=0.0403, 1185 F2 values, 101 variables. The structural analysis of both compounds, highlighting a significant contraction of the Ag-Mg distances, suggests the existence of three-dimensional [Ag-Mg] networks hosting La atoms. LMTO calculations applied to La4Ag10Mg3 indicate that the strongest bonds occur for Ag-Ag and Ag-Mg interactions, and confirm the presence of a 3D∞[Ag10Mg3]δ− polyanionic framework balanced by positively charged La atoms. 相似文献
4.
Ohne Zusammenfassung 相似文献
5.
Anna Maria Cardinale Daniele Macciò Adriana Saccone 《Journal of Thermal Analysis and Calorimetry》2014,116(1):61-67
The isothermal section at 500 °C of the Sm–Al–Si system has been experimentally investigated by using scanning electron microscopy, electron microprobe analysis and X-ray powder diffraction. Four intermetallic compounds have been confirmed: τ1-SmAl2Si2 (hP5-CaAl2Si2 type), τ2-SmAlxSi1?x (tI12-Th2Si type), τ4-SmAl0.5Si0.5 (oS8-CrB type) and τ5-Sm6Al3Si (tI80-Tb6Al3Si type). A new ternary intermediate has been found: τ3-Sm4Al3Si3 that crystallizes orthorhombic isostructural with Pr4Al3Ge3. 相似文献
6.
Gabriella Cavallo Giancarlo Terraneo Alessandro Monfredini Marco Saccone Arri Priimagi Tullio Pilati Giuseppe Resnati Pierangelo Metrangolo Duncan W. Bruce 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(21):6408-6412
Unconventional ionic liquid crystals in which the liquid crystallinity is enabled by halogen‐bonded supramolecular anions [CnF2 n+1‐I⋅⋅⋅I⋅⋅⋅I‐CnF2 n+1]− are reported. The material system is unique in many ways, demonstrating for the first time 1) ionic, halogen‐bonded liquid crystals, and 2) imidazolium‐based ionic liquid crystals in which the occurrence of liquid crystallinity is not driven by the alkyl chains of the cation. 相似文献
7.
Airborne particulate matter (PM) is one of the most important polluting factors in the atmosphere containing solid particles generated during the combustion processes. PM, due to the particle size, is easily inhaled and constitutes a potential hazard for the human health. We previously documented, using in vitro cell culture systems, cytogenetic damages caused by exposure to a non-fractionated PM in two different areas from the city of Catania (Sicily, Italy). In the present work, the PM was fractionated in six different sub-fractions, and the relative extractable organic matters (EOM) were analyzed in order to quantify the presence of Polycyclic Aromatic Hydrocarbons (PHAs), a well known class of genotoxic agents. More than 70% of the total EOM was found in the PM with aerodynamic diameters less than 3.5 microm (PM35), and about 60% of the total EOM was detected between PM0.14 and PM1.2. Also the large amount of all the analyzed PAHs were found between the PM0.14 and PM1.2. The obtained data indicates that the genotoxic effect previously shown on mammalian cells (Chinese hamster epithelial liver cells) should be due, in the large part, to the PM with smaller particle size, namely less than PM1.2. 相似文献
8.
Solokha P De Negri S Skrobanska M Saccone A Pavlyuk V Proserpio DM 《Inorganic chemistry》2012,51(1):207-214
The synthesis, structural characterization, and chemical-bonding peculiarities of the two new polar lanthanum-magnesium germanides La(4)Mg(5)Ge(6) and La(4)Mg(7)Ge(6) are reported. The crystal structures of these intermetallics were determined by single-crystal X-ray diffraction analysis. The La(4)Mg(5)Ge(6) phase crystallizes in the orthorhombic Gd(4)Zn(5)Ge(6) structure type [Cmc2(1), oS60, Z = 4, a = 4.5030(7) ?, b = 20.085(3) ?, c = 16.207(3) ?, wR2 = 0.0451, 1470 F(2) values, 93 variables]. The La(4)Mg(7)Ge(6) phase represents a new structure type with a monoclinic unit cell [C2/m, mS34, Z = 2, a = 16.878(3) ?, b = 4.4702(9) ?, c = 12.660(3) ?, β = 122.25(3)°, wR2 = 0.0375, 1466 F(2) values, 54 variables]. Crystallographic analysis together with linear muffin-tin orbital band structure calculations reveals the presence of strongly bonded 3D polyanionic [Mg-Ge] networks balanced by positively charged La atoms in both stoichiometric compounds. The La(4)Mg(5)Ge(6) compound is related to Zintl phases, showing a prominent density of states pseudogap at the Fermi level. A distinctive feature of the La(4)Mg(5)Ge(6) structure is the presence of Ge-Ge covalent dumbbells; in La(4)Mg(7)Ge(6), the higher Mg content generates a polyanionic network consisting exclusively of Mg-Ge heterocontacts. Nevertheless, the frameworks of the two phases are structurally similar, as is highlighted in this work. 相似文献
9.
F. D. Saccone C. E. Rodríguez Torres F. H. Sánchez M. B. Fernández van Raap 《Hyperfine Interactions》2001,134(1):123-129
RE2Fe14B (RE=rare earth) materials are capable of absorbing hydrogen to form a stable solid solution at room temperature. Hydrogenation produces a number of significant changes in the hyperfine interactions. In this work, 57Fe Mössbauer effect spectroscopy and X-ray diffraction measurements were performed on Nd14.01Hf0.08Fe78.91B7.00 alloys submitted to thermal treatment in hydrogen atmosphere. A non-linear increase of the hyperfine fields and isomer shifts with hydrogen concentration was observed. The hyperfine parameters of the 8j1 site exhibit a rather different evolution than those experienced by the other major sites (8j2, 16k1, 16k2). The origin of the hyperfine field enhancement is analyzed in terms of volume expansion and H nearest neighbors to the Fe sites. A linear expression on these two effects to give account of isomer shift evolution for 8j1 site is given. 相似文献
10.
Riccardo Freccero Dr. Pavlo Solokha Dr. Serena De Negri Prof. Adriana Saccone Prof. Yuri Grin Dr. Frank R. Wagner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(26):6600-6612
A comparative chemical bonding analysis for the germanides La2MGe6 (M=Li, Mg, Al, Zn, Cu, Ag, Pd) and Y2PdGe6 is presented, together with the crystal structure determination for M=Li, Mg, Cu, Ag. The studied compounds adopt the two closely related structure types oS72-Ce2(Ga0.1Ge0.9)7 and mS36-La2AlGe6, containing zigzag chains and corrugated layers of Ge atoms bridged by M species, with La/Y atoms located in the biggest cavities. Chemical bonding was studied by means of the quantum chemical position-space techniques QTAIM (quantum theory of atoms in molecules), ELI-D (electron localizability indicator), and their basin intersections. The new penultimate shell correction (PSC0) method was introduced to adapt the ELI-D valence electron count to that expected from the periodic table of the elements. It plays a decisive role to balance the Ge−La polar-covalent interactions against the Ge−M ones. In spite of covalently bonded Ge partial structures formally obeying the Zintl electron count for M=Mg2+, Zn2+, all the compounds reveal noticeable deviations from the conceptual 8−N picture due to significant polar-covalent interactions of Ge with La and M ≠ Li, Mg atoms. For M=Li, Mg a formulation as a germanolanthanate M[La2Ge6] is appropriate. Moreover, the relative Laplacian of ELI-D was discovered to reveal a chemically useful fine structure of the ELI-D distribution being related to polyatomic bonding features. With the aid of this new tool, a consistent picture of La/Y−M interactions for the title compounds was extracted. 相似文献