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1.
Growth mechanism and structure of electrochemically synthesized dendritic polymethylsilane molecules
Matjaž Valant, Gregor Mali, Artem V. Badasyan, Andraž Mavrič, 2017, original scientific article

Abstract: The study of an electrochemical synthesis of polymethylsilane from trifunctional trichloro- methylsilane monomers identified a single polymerization pathway involving reduction of the monomer to silyl anions and their addition to the growing polymer. The sizes of the synthesized macromolecules, measured with dynamic light scattering, are much larger than the theoretical size estimated for an ideal dendrimer. The reason for this, found by NMR analysis, is in a large number of branching irregularities (defects) contained in the molecular structure, which can be described as a hyperbranched dendritic polymer. Theoretical estimates of sizes for an ideal dendrimer were corrected assuming a branching defect is a cavity with the volume of one monomer. Appropriateness of the theoretical and experimental models was confirmed with a good quantitative agreement between the experimental densities and the theoretically calculated values.
Found in: osebi
Keywords: Polymethylsilane Dendritic polymer Electropolymerization
Published: 20.03.2017; Views: 1191; Downloads: 0
.pdf Fulltext (705,04 KB)

2.
High-temperature stabilization of bulk amorphous Al2O3
Andraž Mavrič, Matjaž Valant, Gregor Mali, Mattia Fanetti, 2018, original scientific article

Abstract: We present a method for high temperature stabilization of bulk amorphous aluminium oxide. The stabilization is achieved by dispersing polysilane dendritic molecules in aluminium hydroxide gel, which upon thermal treatment gives amorphous aluminium oxide stable up to 900 °C. The dispersed macromolecules covalently bind to the alumina matrix and induce homogeneously distributed strain fields that keep the alumina amorphous. The thermal conversion of the precursor system was followed by thermogravimetry with an evolved gas analysis, infrared spectroscopy and 29Si NMR. The amorphous structure of aluminium oxide was confirmed with an X-ray and electron diffraction. Additionally, the amorphous state was supported by presence of penta-coordinated aluminium detected by 27Al NMR and a low bandgap measured by a UV–visible absorption spectroscopy.
Found in: osebi
Keywords: Amorphous aluminium oxide, Polysilane, Nanocomposite, Stabilization
Published: 30.07.2018; Views: 1048; Downloads: 0
.pdf Fulltext (2,67 MB)

3.
The electrochemical synthesis of dendritic polymethylsilane
Matjaž Valant, Gregor Mali, Artem V. Badasyan, Andraž Mavrič, 2017, published scientific conference contribution abstract

Found in: osebi
Keywords: electropolymerization, polysilane, dendrimer
Published: 11.09.2017; Views: 1047; Downloads: 0
.pdf Fulltext (152,81 KB)

4.
A Mechanistic Study of Magnesium Sulfur Batteries
Ana Robba, Alen Vižintin, Jan Bitenc, Gregor Mali, Iztok Arčon, Matjaž Kavčič, Matjaž Žitnik, Klemen Bučar, Giuliana Aquilanti, Charlotte Martineau-Corcos, Anna Randon-Vitanova, Robert Dominko, 2017, original scientific article

Abstract: Magnesium sulfur batteries are considered as attractive energy storage devices due to the abundance of electrochemically active materials and high theoretical energy density. Here we report the mechanism of a Mg-S battery operation, which was studied in the presence of simple and commercially available salts dissolved in a mixture of glymes. The electrolyte offers high sulfur conversion into MgS in the first discharge with low polarization. The electrochemical conversion of sulfur with magnesium proceeds through two well-defined plateaus, which correspond to the equilibrium between sulfur and polysulfides (high-voltage plateau) and polysulfides and MgS (low-voltage plateau). As shown by XANES, RIXS and NMR studies, the end discharge phase involves MgS with Mg atoms in a tetrahedral environment resembling the wurtzite structure, while chemically synthesized MgS crystalizes in the rock-salt structure with octahedral coordination of magnesium.
Found in: osebi
Keywords: magnesium, sulfur, rechargeable batteries, XAS, NMR
Published: 19.10.2017; Views: 1042; Downloads: 0
.pdf Fulltext (1,48 MB)

5.
Unraveling the arrangement of Al and Fe within the framework explains the magnetism of mixed-metal MIL-100(Al,Fe)
Gregor Mali, Matjaž Mazaj, Iztok Arčon, Darko Hanžel, Denis Arčon, Zvonko Jagličić, 2019, original scientific article

Abstract: Properties of mixed-metal MOFs depend on the distribution of different metals within their frameworks. Determination of this distribution is often very challenging. Using an example of aluminum- and iron-containing MIL-100, we demonstrate that 27Al NMR spectroscopy, when combined with first-principles calculations and magnetic, X-band electron paramagnetic resonance, Fe K-edge extended X-ray absorption fine structure, and Mössbauer measurements, enables one to accurately determine the arrangement of Al and Fe within the metal trimers, which are the basic building units of MIL-100. In this particular material, the incorporation of Fe and Al on the framework metal sites is random. Crucial for deciphering the arrangement is detecting NMR signals, shifted because of the strong hyperfine interaction between the 27Al nuclei and the unpaired electronic spins of Fe3+ ions, assigning the shifted signals aided by first-principles calculations of hyperfine couplings, and quantitatively evaluating the NMR intensities and the measured effective magnetic moment.
Found in: osebi
Keywords: Fe EXAFS, XANES, MIL100, MOF, magnetizem
Published: 26.03.2019; Views: 340; Downloads: 0
.pdf Fulltext (2,57 MB)

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