Zoran Mazej

Jožef Stefan Institute, Lubliano, Ljubljana, Slovenia

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Publications (132)270.33 Total impact

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    ABSTRACT: Anomalous chemical shifts, i.e. cases when binding energy decreases with the increase of the oxidation state, have been well-documented for selected compounds of silver, and well understood based on analysis of initial- and final-state effects in the XPS spectra. Here we report two examples of even more exotic behaviour of chemical shifts for two silver compounds. The first one is Ag2S2O7 which exhibits both positive and negative substantial shifts with respect to metallic Ag for two distinct Ag(I) sites in its crystal structure, which differ by as much as 3.6 eV. Another is AgSO4, a rare example of oxo silver (II) salt, which exhibits “normal” chemical shift but the Ag 3d5/2 binding energy takes the largest value measured for a silver (II) compound (370.1 eV). This property is connected predominantly with the extremely strongly oxidizing nature of Ag(II) species.
    Journal of Electron Spectroscopy and Related Phenomena 07/2015; 202. DOI:10.1016/j.elspec.2015.02.013 · 1.55 Impact Factor
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    ABSTRACT: Saturated vapor pressure p° and enthalpy of sublimation (sH°) of cerium tetrafluoride CeF4 were determined by means of Knudsen Effusion Mass Spectrometry (KEMS) in the range of 750 - 920 K. It was discovered that sublimation of cerium tetrafluoride from a platinum effusion cell competes with thermal decomposition to CeF3 in the solid phase but no accompanying release of fluorine to the gas phase does occur. Thus, fluorine atoms migrate within the surface layer of CeF4(s) to the regions of their irreversible drain. We used Scanning Electron Microscopy (SEM) to study the distribution of the residual CeF3(s) across the inner surface of the effusion cell after complete evaporation of CeF4(s). It was observed that CeF3 accumulates near the edge of the effusion orifice and near the junction of the lid and the body of the cell, i.e. in those regions where the fluorine atoms can migrate to a free platinum surface and thus be depleted from the system. Distribution of CeF3(s) solid particles indicates the ways of fluorine atoms migration providing CeF3(s) formation inside the CeF4(s) surface layer.
    The Journal of Physical Chemistry A 07/2015; DOI:10.1021/acs.jpca.5b04105 · 2.78 Impact Factor
  • Zoran Mazej, Evgeny Goreshnik
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    ABSTRACT: Compounds (III) and (V) (yields given in mg) are characterized by single crystal XRD and Raman spectroscopy.
    ChemInform 05/2015; 46(21). DOI:10.1002/chin.201521013
  • Zoran Mazej, Evgeny A. Goreshnik
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    ABSTRACT: N2H6(Sb2F11)2 was synthesized by the reaction of N2H6F2 with excess of SbF5 in anhydrous hydrogen fluoride (aHF). It crystallizes in the triclinic space group P (No. 2) with a = 6.6467(3) Å, b = 8.3039(4) Å, c = 8.3600(5) Å, α = 76.394(5) o, β = 70.161(5) o, γ = 70.797(5) o, V = 405.90(4) Å3 at 150 K, Z = 2. When it is redissolved in aHF, it solvolysis with the release of SbF5 yielding N2H6(SbF6)2 which crystallizes in the monoclinic C2/c space group (No. 15) with a = 7.3805(3) Å, b = 12.3248(5) Å, c = 10.4992(4) Å, β = 92.218(4) o, V = 954.33(7) Å3 at 150 K, and Z = 8. No other phases were observed in crystallization products when different molar ratios of N2H6F2/SbF5 (1:1,2:3,1:3) in aHF were used as starting materials.
    Zeitschrift für anorganische Chemie 04/2015; 641(7). DOI:10.1002/zaac.201500110 · 1.25 Impact Factor
  • Zoran Mazej, Evgeny A. Goreshnik
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    ABSTRACT: The colourless HgFAsF6 was synthesized by oxidation of Hg2(AsF6)2 with elemental fluorine in anhydrous hydrogen fluoride. It crystallizes in the monoclinic space group P21/c with a=7.0645(3) Å, b=9.9023(3) Å, c=7.8686(3) Å, β=102.960(4) o V=536.43(3) Å3, and Z=4 at 150 K. The structure of HgFAsF6 consists of infinite zig-zag -[Hg-F-Hg]- chains oriented parallel to each other along the b axis and interconected by AsF6 groups. Hg(HF)2(AsF6)2 crystallizes in the triclinic space group P with a=5.0781(3) Å, b=6.6907(5) Å, c=7.7135(5) Å, α=84.045(5), β=79.277(5) o, γ=80.612(6), V=253.32(3) Å3, and Z=1 at 150 K. The crystal structure is composed of infinite columns of Hg atoms linked by AsF6 groups. Each pair of adjacent Hg atoms is bridged by two AsF6 groups. The coordination of Hg is completed by two F atoms provided by HF molecules. Hg(HF)(AsF6)2 crystallizes in the monoclinic space group P21/c with a=9.4921(8) Å, b=9.2834(6) Å, c=10.5448(7) Å, β=103.795(7) o, V=902.53(12) Å3, and Z=4 at 150 K and it is isotypic to Cd(HF)(AsF6)2. The new mixed-anion compound Hg(AsF6)(SO3F) crystallizes in the monoclinic space group P21/c with a=5.1975(8) Å, b=18.046(3) Å, c=15.873(5) Å, β=93.614(13) o, V=1485.9(6) Å3, and Z=4 at 200 K. All three oxygen atoms from each SO3F group utilize for bonding with three Hg atoms. The Hg1 (Hg2) atoms are coordinated by two (four) oxygen atoms from two (four) SO3F groups and by six (three) fluorine atoms from AsF6 groups forming on that way tridimensional framework.
    Journal of Solid State Chemistry 04/2015; 228. DOI:10.1016/j.jssc.2015.04.025 · 2.20 Impact Factor
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    ABSTRACT: The reaction between colourless AgSbF6 and sky-blue Ag(SbF6)2 (molar ratio 2:1) in gaseous HF at 323 K yields green Ag3(SbF6)4, a new mixed-valence ternary fluoride of silver. Unlike in all other Ag(I)/Ag(II) systems known to date, the Ag+ and Ag2+ cations are randomly distributed on a single 12b Wyckoff position at the axis of the I3d cell. Each silver forms four short (4 × 2.316(7) Å) and four long (4 × 2.764(6) Å) contacts with the neighbouring fluorine atoms. The valence bond sum analysis suggests that such coordination would correspond to a severely overbonded Ag(I) and strongly underbonded Ag(II). Thorough inspection of thermal ellipsoids of the fluorine atoms closest to Ag centres reveals their unusual shape, indicating that silver atoms must in fact have different local coordination spheres; this is not immediately apparent from the crystal structure due to static disorder of fluorine atoms. The Ag K-edge XANES analysis confirmed that the average oxidation state of silver is indeed close to +1⅓. The optical absorption spectra lack features typical of a metal thus pointing out to the semiconducting nature of Ag3(SbF6)4. Ag3(SbF6)4 is magnetically diluted and paramagnetic (μeff = 1.9 μB) down to 20 K with a very weak temperature independent paramagnetism. Below 20 K weak antiferromagnetism is observed (Θ = −4.1 K). Replacement of Ag(I) with potassium gives K(I)2Ag(II)(SbF6)4 which is isostructural to Ag(I)2Ag(II)(SbF6)4. Ag3(SbF6)4 is a genuine mixed-valence Ag(I)/Ag(II) compound, i.e. Robin and Day Class I system (localized valences), despite Ag(I) and Ag(II) adopting the same crystallographic position.
    Dalton Transactions 03/2015; 44(24). DOI:10.1039/C5DT00740B · 4.10 Impact Factor
  • Zoran Mazej, Evgeny A. Goreshnik
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    ABSTRACT: NO2SbF6 crystalizes at 150 K in the orthorhombic Cmmm space group (No. 65) with a = 6.8119(7) Å, b = 7.3517(7) Å, c = 5.5665(5) Å, V = 278.77(5) Å3, and Z = 2. Its crystal structure exhibits a different packing of the [NO2]+ and [SbF6]− ions than in the known crystal structure of NO2AsF6. The XeF5SbF6 compound is orthorhombic at 150 K, space group Pnma (No. 62), with a = 16.7159(6) Å, b = 8.1093(3) Å, c = 5.7576(2) Å, V = 780.47(5) Å3, Z = 4, and it is isotypic with the known XeF5MF6 crystal structures of M = Nb, Ru, and Pt. The unit cell of XeF5Sb2F11 is triclinic at 200 K, P̄1 space group (No. 2), with a = 8.5223(8) Å, b = 8.5582(8) Å, c = 9.2012(8) Å, α = 68.799(8) o, β = 74.897(8) o, γ = 76.252(8) o, V = 596.35(10) Å3 and Z = 2. Each [XeF5]+ cation has four interactions with the three [Sb2F11]− anions.
    Journal of Fluorine Chemistry 03/2015; 175. DOI:10.1016/j.jfluchem.2015.03.004 · 1.95 Impact Factor
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    ABSTRACT: The PbFSbF6 and three compounds with hydrogen fluoride (HF) bonded directly to the metal centre (Pb2F2(HF)(SbF6)2 and Ba(HF)(AF6)2: (A = As, Sb) were structurally characterized. Pb2F2(HF)(SbF6)2 crystallizes in the orthorhombic space group Pbca with a = 13.0470(3) Å, b = 10.3366(3) Å, c = 18.2427(5) Å, V = 2460.24(11) Å3 at 200 K, Z = 8. The main feature of its crystal structure is formation of the ribbon-like [Pb4F4]4+ units, which are further connected by SbF6− units into three dimensional framework. Similar [Pb − F]nn+ ribbon-like polymers are observed in the crystal structure of PbFSbF6. The later crystallizes in the triclinic space group P̄1 with a = 4.7439(5) Å, b = 7.4001(6) Å, c = 7.6940(8) Å, α = 106.218(8)o, β=102.220(9)o, γ = 90.479(7)o, V = 252.82(5) Å3 at 150 K, Z = 2. Single crystals of Ba(HF)(AF6)2 (A = Sb, As) were prepared and structurally characterized. These two compounds crystallize in the orthorhombic space group Pbcn, Z = 8 with following cell dimensions; A = Sb: a = 11.0231(3) Å, b = 16.0557(4) Å, c = 11.7044(4) Å, V = 2071.49(10) Å3; A = As: a = 10.7149(9) Å, b = 15.7256(15) Å, c = 11.2027(9) Å, V = 1887.6(3) Å3 (both at 200 K), Z = 8.
    Journal of Fluorine Chemistry 03/2015; 175. DOI:10.1016/j.jfluchem.2015.03.002 · 1.95 Impact Factor
  • Wojciech Grochala, Zoran Mazej
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    ABSTRACT: Silver is the heavier congener of copper in the Periodic Table, but the chemistry of these two elements is very different. While Cu(II) is the most common cationic form of copper, Ag(II) is rare and its compounds exhibit a broad range of peculiar physico-chemical properties. These include, but are not limited to: (i) uncommon oxidizing properties, (ii) unprecedented large mixing of metal and ligand valence orbitals, (iii) strong spin-polarization of neighbouring ligands, (iv) record large magnetic superexchange constants, (v) ease of thermal decomposition of its salts with O-, N- or C-ligands, as well as (vi) robust Jahn-Teller effect which is preserved even at high pressure. These intriguing features of the compounds of Ag(II) will be discussed here together with (vii) a possibility of electromerism (electronic tautomerism) for a certain class of Ag(II) salts. © 2015 The Author(s) Published by the Royal Society. All rights reserved.
    Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences 03/2015; 373(2037). DOI:10.1098/rsta.2014.0179 · 2.86 Impact Factor
  • Zoran Mazej, Evgeny Goreshnik
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    ABSTRACT: New types of [XeF5]+ salts, i.e., NO2XeF5(SbF6)2 and XeF5[Cu(SbF6)3], are derived from reactions between XeF5SbF6 and NO2SbF6 or Cu(SbF6)2, respectively. The crystal structure of the former consists of [NO2]+ and [XeF5]+ cations and [SbF6]- anions. The main feature of the crystal structure of XeF5[Cu(SbF6)3] are rings of CuF6 octahedra that share apexes with SbF6 octahedra connected into an infinite tridimensional framework. This arrangement leads to the formation of cavities within which [XeF5]+ cations are located. Raman spectra of both [NO2]+/[XeF5]+ and [XeF5]+/Cu2+ mixed-cation hexafluorido-antimonates(V) are reported herein.
    European Journal of Inorganic Chemistry 03/2015; 2015(8):1453–1456. DOI:10.1002/ejic.201500028 · 2.97 Impact Factor
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    ABSTRACT: Crystalline phases obtained by reactions of MSO3F (M: Na, K, Rb, Cs), AgSO3F, and (SO3F)2 (77 K room temp., 2—5 d) are characterized by powder XRD, Raman spectroscopy, and magnetic measurements.
    ChemInform 03/2015; 46(12). DOI:10.1002/chin.201512024
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    Dataset: Na2AgF4 SI
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    ABSTRACT: The syntheses and characterizations of mixed-cation fluorosulfates containing AgII ions are reported and add to the moderately well-known chemistry of AgII compounds. The compounds synthesized mostly show different structures and compositions. The mixed sodium–silver fluorosulfate is isostructural with Ag3(SO3F)4 (monoclinic P21/c, a = 5.2812 Å, b = 13.0473 Å, c = 19.3557 Å, and β = 100.970°) and has the composition (Ag0.05Na0.95)(Ag0.65Na0.35)AgII(SO3F)4. The mixed potassium–silver fluorosulfate does not correspond to KI2AgII(SO3F)4 but rather to KAgI2AgII(SO3F)5 [orthorhombic P2221, a = 6.4736(3) Å, b = 7.3915(4) Å, and c = 17.7736(10) Å]. Two rubidium–silver fluorosulfates form as a mixture, one corresponds to RbAgI2AgII(SO3F)5 [orthorhombic P2221, a = 6.4828(6) Å, b = 7.3551(7) Å, c = 18.0262(17) Å], and the other corresponds to RbAgII(SO3F)3 [monoclinic P21/m, a = 15.8152(14) Å, b = 15.4861(13) Å, c = 17.0211(14) Å, and β = 101.513(5)°]. The cesium fluorosulfate/silver(II) fluorosulfate phase diagram is exemplified by the CsAgII(SO3F)3 salt [triclinic P, a = 14.9241(5) Å, b = 9.7046(3) Å, c = 17.8465(7) Å, α = 109.116(2)°, β = 84.655(3)°, and γ = 119.171(3)°]. The IR and Raman spectra of the compounds were measured, and their thermal stability and magnetic properties have been determined. The MAgI2AgII(SO3F)5 systems show antiferromagnetic behavior with absolute superexchange constants of up to 19.1 meV for M = K, and ferromagnetism can be observed below 20–40 K for the MAg(SO3F)3 derivatives (M = Rb, Cs).
    Berichte der deutschen chemischen Gesellschaft 12/2014; 2015(2). DOI:10.1002/ejic.201402948
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    Zoran Mazej, Evgeny Goreshnik
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    ABSTRACT: The KM(AsF6)3 (M2+ = Mg, Co, Mn, Zn) and KCu(SbF6)3 compounds crystallize isotypically to previously known KNi(AsF6)3. The main features of the structure of these compounds are rings of MF6 octahedra sharing apexes with AsF6 octahedra connected into infinite tri-dimensional frameworks. In this arrangement cavities are formed where K+ cations are placed. Single crystals of CoSr5(AsF6)12·8HF were obtained as one of the products after the crystallization of 3KF/CoF2/SrF2 mixture in the presence of AsF5 in anhydrous HF. The CoSr5(AsF6)12·8HF is monoclinic, C/2c (No.15), with a = 26.773(5) Å, b = 10.087(2) Å, c = 21.141(5) Å, β = 93.296(13) °, V = 5699.9(19) Å3 at 200 K, and Z = 4. There are three crystallographically non-equivalent Sr2+ cations in the crystal structure of CoSr5(AsF6)12·8HF. The Sr1 is coordinated by ten fluorine atoms from eight different [AsF6]- anions, meanwhile Sr2 and Sr3 are bound to nine fluorine atoms provided by one HF and eight AsF6 units or by two HF and six AsF6 units, respectively. The Co2+ is coordinated distorted-octahedrally by six fluorine atoms from two HF molecules and four different AsF6 units. All those moieties in the crystal strucutre of [Co(HF)2]Sr[Sr(HF)]2[Sr(HF)2]2[AsF6]12 are connected into tridimensional framework. The CoSr5(AsF6)12·8HF is a unique example of compound where HF molecules are directly bound via fluorine atoms to two different metal centres.
    12/2014; 230(2):123–130. DOI:10.1515/zkri-2014-1791
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    ABSTRACT: Several types of mixed-anion fluoride-chloride phases of silver(I) (with stoichiometries close to AgF0.5Cl0.5 and AgF0.75Cl0.25) have been synthesized for the first time in reactions between AgF (or AgF2, respectively) and AgCl. The products crystallize in the rock salt unit cell, similarly to the pristine AgF and AgCl phases. The members of the Ag(F1−xClx) series exhibit an almost linear relationship of the cubic cell vector with the composition parameter, x, which indicates that AgF and AgCl form a solid solution with a disordered anionic sublattice. The AgF0.5Cl0.5 phase exhibits quite a low melting point of 307 °C (as compared with 435 °C for AgF and 455 °C for AgCl), and small entropy change at melting, some 10 J (mol K)−1 (as compared to 23.6 J (mol K)−1 for AgF, and 18.1 J (mol K)−1 for AgCl), indicative of high disorder and large absolute entropy of AgF0.5Cl0.5 solid. Despite that, the Ag(F1−xClx) phases show smaller specific electric conductance than the end members of the series, AgCl and AgF. Parent AgF turns out to have rather high specific conductance of 3 × 10−2 mS cm−1 at a room temperature and rather small activation energy for conductivity (29.2 kJ mol−1) which suggest the presence of high concentration of defects and substantial electron doping to the conduction band.
    Journal of Fluorine Chemistry 09/2014; 174. DOI:10.1016/j.jfluchem.2014.09.004 · 1.95 Impact Factor
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    ABSTRACT: Crystals of [ImH]2[TiF6]·2HF (I) (Im: imidazole), [ImH]3[Ti2F11] (II), [ImH]4[Ti4F20] (III), [ImH3][Ti5F23] (IV), and [ImH][Ti2F9] (V) are prepared from stoichiometric mixtures of imidazole and TiF4 in anhydrous HF (-196 °C followed by warming to ambient temperature) and characterized by single crystal XRD, Raman spectroscopy, and quantum chemical B3LYP calculations.
    ChemInform 10/2013; 44(40). DOI:10.1002/chin.201340017
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    ABSTRACT: Reactions between imidazole (Im, C3H4N2) and TiF4 in anhydrous hydrogen fluoride (aHF) in different molar ratios have yielded [ImH]2[TiF6]·2HF, [ImH]3[Ti2F11], [ImH]4[Ti4F20], [ImH]3[Ti5F23], and [ImH][Ti2F9] upon crystallization. All five structures were characterized by low-temperature single-crystal X-ray diffraction. The single-crystal Raman spectra of [ImH]4[Ti4F20], [ImH]3[Ti5F23], and [ImH][Ti2F9] were also recorded and assigned. In the crystal structure of [ImH]2[TiF6]·2HF, two HF molecules are coordinated to each [TiF6](2-) anion by means of strong F-H···F hydrogen bonds. The [Ti2F11](3-) anion of [ImH]3[Ti2F11] results from association of two TiF6 octahedra through a common fluorine vertex. Three crystallographically independent [Ti2F11](3-) anions, which have distinct geometries and orientations, are hydrogen-bonded to the [ImH](+) cations. The [ImH]4[Ti4F20] salt crystallized in two crystal modifications at low (α-phase, 200 K) and ambient (β-phase, 298 K) temperatures. The tetrameric [Ti4F20](4-) anion of [ImH]4[Ti4F20] consists of rings of four TiF6 octahedra, which each share two cis-fluorine vertices, whereas the pentameric [Ti5F23](3-) anion of [ImH]3[Ti5F23] results from association of five TiF6 units, where four of the TiF6 octahedra share two cis-vertices, forming a tetrameric ring as in [Ti4F20](4-), and the fifth TiF6 unit shares three fluorine vertices with three TiF6 units of the tetrameric ring. The [ImH][Ti2F9] salt also crystallizes in two crystal modifications at low (α-phase, 200 K) and high (β-phase, 298 K) temperatures and contains polymeric ([Ti2F9](-))∞ anions, which appear as two parallel infinite zigzag chains comprised of TiF6 units, where each TiF6 unit of one chain is connected to a TiF6 unit of the second chain through a shared fluorine vertex. Quantum-chemical calculations at the B3LYP/SDDALL level of theory were used to arrive at the gas-phase geometries and vibrational frequencies of the [Ti4F20](4-) and [Ti5F23](3-) anions, which aided in the assignment of the experimental vibrational frequencies of the anion series.
    Inorganic Chemistry 07/2013; 52(15). DOI:10.1021/ic302468j · 4.79 Impact Factor
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    ABSTRACT: The evaporation and decomposition of cerium tetrafluoride CeF4(s) at high temperatures were studied by means of Knudsen Effusion Mass Spectrometry (KEMS). The saturated vapor pressure over CeF4(s) was determined by the isothermal evaporation of the sample from Pt Knudsen cell. The enthalpy of CeF4(s) sublimation was calculated using the second and the third laws of thermodynamics.
    ECS Transactions 06/2013; 46(1):191-195. DOI:10.1149/04601.0191ecst
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    ABSTRACT: We demonstrate that the intrinsic electron doping of monolayer epitaxial graphene on SiC(0001) can be tuned in a controlled fashion to holes via molecular doping with the fluorinated fullerene C60F48. In situ angle-resolved photoemission is used to measure an upward shift of (0.6 ± 0.05) eV in the Dirac point from −0.43 eV to +0.17 eV relative to the Fermi level. The carrier density is observed to change from n ∼ (1 × 1013 ± 0.1 × 1013) cm−2 to p ∼ (2 × 1012 ± 1 × 1012) cm−2. We introduce a doping model employing Fermi-Dirac statistics which explicitly takes temperature and the highly correlated nature of molecular orbitals into account. The model describes the observed doping behaviour in our experiment and readily explains why net p-type doping was not achieved in a previous study [Coletti et al., Phys. Rev. B 81, 8 (2010)] which used tetrafluorotetra-cyanoquinodimethane (F4-TCNQ).
    Applied Physics Letters 06/2013; 102(24):241601. DOI:10.1063/1.4811248 · 3.52 Impact Factor

Publication Stats

477 Citations
270.33 Total Impact Points

Institutions

  • 1998–2015
    • Jožef Stefan Institute
      • Department of Inorganic Chemistry and Technology K1
      Lubliano, Ljubljana, Slovenia
  • 2010
    • University of Warsaw
      Warszawa, Masovian Voivodeship, Poland
  • 2005–2010
    • University of Ljubljana
      Lubliano, Ljubljana, Slovenia
  • 2009
    • University of Nova Gorica
      Gorica, Nova Gorica, Slovenia
    • Warsaw University of Technology
      Warszawa, Masovian Voivodeship, Poland