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  • 1. Asanou, I. P.
    et al.
    Bulusheva, L. G.
    Dubois, M.
    Yudanov, N. F.
    Alexeev, A. V.
    Makarova, Tatiana L.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Okotrub, A. V.
    Graphene nanochains and nanoislands in the layers of room-temperature fluorinated graphite2013In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 59, 518-529 p.Article in journal (Refereed)
    Abstract [en]

    Intercalated compound of graphite fluoride with n-heptane has been synthesized at room temperature using a multi-stage process including fluorination by a gaseous BrF3 and a set of intercalant exchange reactions. It was found that composition of the compound is CF0.40(C7H16)(0.04) and the guest molecules interact with the graphite fluoride layers through the van der Waals forces. Since the distance between the filled layers is 1.04 nm and the unfilled layers are separated by similar to 0.60 nm, the obtained compound can be considered as a stack of the fluorinated graphenes. These fluorinated graphenes are large in area making it possible to study local destruction of the a conjugated system on the basal plane. It was shown that fluorine atoms form short chains, while non-fluorinated sp(2) carbon atoms are organized in very narrow ribbons and aromatic areas with a size smaller than 3 nm. These pi electron nanochains and nanoislands preserved after the fluorination process are likely responsible for the value of the energy gap of the compound of similar to 2.5 eV. Variation in the size and the shape of pi electron regions within the fluorinated graphene layers could be a way for tuning the electronic and optical characteristics of the graphene-based materials.

  • 2. Belavin, V.V.
    et al.
    Bulusheva, L.G.
    Okotrub, A.V.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Physics.
    Magnetic ordering in C60 polymers with partially broken intermolecular bonds2004In: Physical Review B, Vol. 70, 155402- p.Article in journal (Refereed)
  • 3. Biryulin, YF
    et al.
    Kurdybaylo, D
    Shamanin, V
    Aleksjuk, G
    Volkova, T
    Melenevskaya, E
    Saydashev, I
    Eidelman, E
    Makarova, Tatiana
    Ioffe Physico-Technical Institute RAS, Russia.
    Terukov, E
    Zaitseva, N
    Negrov, V
    Tkatchyov, A
    Strongly non-linear carbon nanofibre influence on electrical properties of polymer composites2008In: Fullerenes, nanotubes, and carbon nanostructures (Print), ISSN 1536-383X, E-ISSN 1536-4046, Vol. 16, no 5-6, 629-633 p.Article in journal (Refereed)
    Abstract [en]

    Composites of carbon nanofibres (CNF) (30-50 nm diam., length up to 1 mu m) in two polymer matrices (polybutadiene-styrene and polypyrrhol) show strong non-linearities of conductivity vs. CNF concentration. We have studied their voltage-current dependencies, and observed correlation of their extrema and layer morphology. Multistability of conductivity is discovered, with apparent effect of magnetic field effect on it in polypyrrhol-based composites. In addition CNF spatial configuration influence on layers' conductivity is discussed.

  • 4. Boukhvalov, D.W.
    et al.
    Karimov, R.F.
    Kurmaev, E.Z.
    Hamilton, T.
    Moewes, A.
    Finkelstein, L.D.
    Katsnelson, M.I.
    Davydov, V.A.
    Rakhmanina, A.V.
    Makarova, Tatiana
    Umeå University.
    Kopelevich, Yakov
    Chiuzbaian, S.
    Neumann, M.
    Testing the magnetism of polymerized fullerene2004In: Physical Review B, Vol. 69, no 11, 115425- p.Article in journal (Refereed)
  • 5. Buga, Sergei G.
    et al.
    Blank, Vladimir D.
    Serebryanaya, Nadejda R.
    Dzwilewski, Andrzej
    Umeå University, Faculty of Science and Technology, Physics.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Physics.
    Electrical properties of 3D-polymeric crystalline and disordered C60 and C70 fullerites.2005In: Diamond and Related Materials vol. 14, special Issue (3-7): Proceedings of Diamond'04, 15th European Conference on Diamond and Diamond-Like Materials, Riva del Garda, Italy 2004., Elsevier B.V. , 2005, 896-901 p.Conference paper (Refereed)
    Abstract [en]

    Crystalline and disordered 3D-polymeric C60 and C70 with different lattice parameters and with densities in the range of 2.2÷3.25 g cm−1 were obtained by high-pressure-high-temperature treatment at P=11.5÷15 GPa, T=670÷1800 K. Their d.c. electrical conductivity was investigated at temperatures 30÷350 K. The variable range hopping mechanism dominates in all samples up to room temperature. A temperature activated conductivity via delocalized states was observed at T>160÷260 K in crystalline C60 samples and in some samples with disordered structure. The evaluated band gap value is Eg=0.28÷0.54 eV for different crystalline structures and 0.06÷0.25 eV for disordered ones

  • 6. Danishevskii, AM
    et al.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sitnikova, AA
    Shanina, BD
    Characteristics of magnetism in nanoporous carbon with palladium clusters2011In: Physics of the solid state, ISSN 1063-7834, E-ISSN 1090-6460, Vol. 53, no 5, 1017-1024 p.Article in journal (Refereed)
    Abstract [en]

    The magnetic properties of samples of nanoporous carbon with palladium clusters prepared from polycrystalline SiC have been studied over a wide range of temperatures. The specific magnetic moment rapidly decreases with increasing temperature. The obtained experimental magnetization curves have a nonlinear character but do not reach saturation even in a field of 10 kOe. Being constructed as functions of H/T, they lie on a universal curve, which suggests superparamagnetism of the system. The experimental curves have a hysteresis. The coercive force, first, decreases with increasing temperature and, then (in the range of 5–20 K), increases, thus forming a notch singularity. On the contrary, the residual magnetization rapidly decreases with increasing temperature. A conclusion on the prevailing contribution of superparamagnetic clusters to the magnetic subsystem is made.

  • 7.
    Han, Kyoo-Hyun
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Physics.
    Zakharova, I.B.
    Serenkov, I.T.
    Sakharov, V.I.
    Proton bombardment of Hard Carbon2006In: Fullerenes, Nanotubes and Carbon Nanostructures vol. 14 issue 2&3: Proceedings of the International Workshop on Fullerenes and Atomic Clusters 2005 (IWFAC2005), St. Petersburg, 2006, 381-384 p.Conference paper (Refereed)
  • 8.
    Han, Kyoo-Hyun
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Talyzin, Alexandr
    Umeå University, Faculty of Science and Technology, Physics.
    Dzwilewski, Andrzej
    Umeå University, Faculty of Science and Technology, Physics.
    Makarova, Tatiana
    Höhne, Roland
    Esquinazi, Pablo
    Spemann, D.
    Dubrovinsky, Leonid S.
    Magnetic properties of carbon phases synthesized using high-pressure high-temperature treatment.2005In: Physical Review B, Vol. 72, 224424- p.Article in journal (Refereed)
  • 9.
    Iwasiewicz-Wabnig, Agnieszka
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Makarova, Tatiana L.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Department of Physics.
    No insulator-metal transition in Rb4C60 under pressure below 2 GPaIn: Physical Review BArticle in journal (Refereed)
  • 10.
    Iwasiewicz-Wabnig, Agnieszka
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Absence of an insulator-metal transition in Rb4C60 up to 2 GPa2008In: Physical Review B, ISSN 0163-1829, Vol. 77, no 8, 085434- p.Article in journal (Refereed)
    Abstract [en]

    We present the results of direct resistance measurements on Rb4C60 under pressures up to 2 GPa. At all pressures covered by this study and over the temperature range of 90–450 K Rb4C60 is a semiconductor with a weakly pressure dependent band gap near 0.7 eV. We do not observe the insulator-to-metal transition previously reported to occur below 1.2 GPa, although we cannot rule out the possibility that such a transition might occur at some significantly higher pressure. The measured resistivity is surprisingly low and is dominated by carriers excited over a 0.1 eV gap. Because the corresponding conductivity increases with deformation of the sample, we assign these states to structural or orientational defects. The known structural transformation below 0.5 GPa leads to a decrease in resistivity under high pressure, but the material remains semiconducting. A Rb6C60 control sample showed a similar behavior, also being a semiconductor under all conditions studied. At temperatures above 460 K, Rb was partially lost from our samples, resulting in metallization by a transformation into Rb3C60.

  • 11. Kvyatkovskii, E.
    et al.
    Zacharova, I.B.
    Shelankov, Andrei
    Umeå University, Faculty of Science and Technology, Physics.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Physics.
    Spin-transfer mechanism of ferromagnetism in polymerized fullerenes: Ab initio calculations2005In: Physical Review B, Vol. 72, no 21, 214426- p.Article in journal (Refereed)
  • 12. Kvyatkovskii, O.E.
    et al.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Physics.
    Zacharova, I.B.
    Shelankov, Andrei
    Umeå University, Faculty of Science and Technology, Physics.
    Quantum-chemical ab initio calculations of the structure, energetics, and electronic properies of the calculations C60 neutral and charged dimers2004In: AIP Conference Proceedings vol. 723, 2004, 385- p.Conference paper (Refereed)
  • 13. Kvyatkovskii, Oleg E
    et al.
    Zacharova, Irina B
    Shelankov, Andrei
    Umeå University, Faculty of Science and Technology, Department of Physics. A.F. Ioffe Physico‐Technical Institute of the RAS , St. Petersburg, Russia .
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Department of Physics. A.F. Ioffe Physico‐Technical Institute of the RAS , St. Petersburg, Russia .
    Magnetic transition in the polymerized fullerene matrix2006In: Fullerenes, Nanotubes and Carbon Nanostructures vol. 14, issue 2&3: Proceedings of the International Workshop on Fullerenes and Atomic Clusters 2005 (IWFAC2005), St. Petersburg, Taylor & Francis, 2006, Vol. 2-3, 373-380 p.Conference paper (Refereed)
    Abstract [en]

    A mechanism of the ferromagnetism in the polymerized fullerene phase is proposed. We show that non‐magnetic defects and impurities give rise to a magnetic transition in the polymerized fullerene matrix. In our model, C60 molecules acquire spin and charge and become magnetically active due to the spin and charge transfer from non‐magnetic dopants. The interaction between magnetic moments of the arising paramagnetic species (C60 ± ions or C60 R radical adducts) dispersed in the polymeric network is inspected by using ab initio Hartree‐Fock and B3LYP hybrid density functional methods. It is revealed that the interaction is ferromagnetic and large enough for creating the high‐T c magnetism.

  • 14. Kvyatkovskii, Oleg E
    et al.
    Zakharova, Irina B
    Shelankov, Andrei L
    Umeå University, Faculty of Science and Technology, Department of Physics. A. F. Ioffe Physico‐Technical Institute of the RAS , St. Petersburg, Russia .
    Makarova, Tatiana L
    Umeå University, Faculty of Science and Technology, Department of Physics. A. F. Ioffe Physico‐Technical Institute of the RAS , St. Petersburg, Russia .
    Magnetic properties of polymerized fullerene doped with hydrogen, fluorine and oxygen2006In: Fullerenes, nanotubes, and carbon nanostructures (Print), ISSN 1536-383X, E-ISSN 1536-4046, Vol. 14, no 2-3, 385-389 p.Article in journal (Refereed)
    Abstract [en]

    We have presented recently a mechanism of ferromagnetism in polymeric fullerene phases based on spin and charge transfer from nonmagnetic donor or acceptor centers into fullerene molecules. In this work, the interaction between magnetic moments of the paramagnetic C60R radical adducts (R = H, F, OH) dispersed in the 2D polymeric network is examined by using UB3LYP hybrid density functional method at 3-21G level. The results show that the interaction is ferromagnetic, strong and long-range.

  • 15.
    Liu, Bingbing
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Physics.
    Nyeanchi, Emmanuel B.
    Umeå University, Faculty of Science and Technology, Physics.
    Makarova, Tatiana L.
    Umeå University, Faculty of Science and Technology, Physics.
    Zhu, Xiaomei
    Umeå University, Faculty of Science and Technology, Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Physics.
    Yang, R.
    Li, D.
    Gao, C.
    Yang, H.
    Zou, Guangtian
    Li, H.-D.
    Olsson, Eva
    Synthesis and characterization of single-walled nanotubes produced with Ce as catalyst2000In: Molecular Materials: Molecular Crystals and Liquid Crystals Section C, vol. 13: Proceedings of the 4th International Workshop on Fullerenes and Atomic Clusters (IWFAC'99), St. Petersburg 1999, Overseas Publishers Association N.V. , 2000, 75-80 p.Conference paper (Refereed)
    Abstract [en]

    We have studied the effect of using rare-earth elements C (typically +4 oxide state) and Eu (typically +2 oxide state) together with nanometer Ni as catalysts to synthesize SWNT in high yield by arc evaporation. A black collar deposit containing mainly SWNT was formed in the presence of Ce/Ni while only nanometer carbon particles were formed using Eu/Ni, as identified by SEM, TEM and Raman spectra. The Raman spectra of our SWNT mats show difference from spectra shown in the literature in a low frequency range, indicating that our mats contain chiral tubes. The temperature dependent resistance of SWNT mats was also measured. A semiconducting behaviour was observed with a negative dR/dT and no resistance minimum from 2 to 350 K. The resistance follows a 2D variable range hopping behaviour.

  • 16. Lubchik, SB
    et al.
    Khodorkovskii, M
    Makarova, T
    Umeå University. Umeå University, Faculty of Science and Technology, Physics.
    Waste conversion into activated carbon for heavy metal removal from waste water2008In: RECENT ADVANCES IN ADSORPTION PROCESSES FOR ENVIRONMENTAL PROTECTION AND SECURITY: Nato Science for Peace and Security Series C - Environmental Security, 2008, 133-146 p.Chapter in book (Other (popular science, discussion, etc.))
  • 17.
    Makarova, T. L.
    Umeå University.
    Graphite under the magnetic force microscope2007In: Physica status solidi. B, Basic research, ISSN 0370-1972, Vol. 244, no 11, 4138-4142 p.Article in journal (Refereed)
  • 18.
    Makarova, T. L.
    Umeå University.
    Magnetic properties of nanocarbon2007In: Diamond and related materials, ISSN 0925-9635, Vol. 16, no 10, 1841-1846 p.Article in journal (Refereed)
  • 19. Makarova, T
    et al.
    Lyubchik, SB
    Lyubchik, AI
    Lygina, ES
    Lyubchik, SI
    Vital, J
    do Rego, AMB
    Fonseca, IM
    Simultaneous removal of 3d transition metals from multi-component solutions by activated carbons from co-mingled wastes2008In: : SEPARATION AND PURIFICATION TECHNOLOGY, 60 (3): 264-271 MAY 6 2008, Vol. 60, no 3, 264-271 p.Article in journal (Refereed)
    Abstract [en]

    The main purpose of the present work was to study the simultaneous removal of 3d transition metals from multi-component solutions by novel porous material obtained from carbon-containing liquid and solid waste. The activated carbon was prepared from co-mingled natural organic waste: 25% sunflower husks, 50% petroleum waste and 25% low-grade bituminous coal. The porous carbon material was obtained via stages of pre-oxidation with binary eutectic Na/K carbonates (in order to avoid melting and coke formation), followed by "step by step" carbonization at 100-400 degrees C in an inert atmosphere and activation with steam at 850 degrees C.The adsorption of the 3d transition metals: copper (II), cobalt (III), nickel (II), iron (III), and chromium (III), on novel activated carbons has been investigated using multi-component model solutions. Experiments have been carried out on the thermodynamics of the simultaneous adsorption of the 3d transition metals in a static mode. The total metal removal combines the process of metal hydroxide precipitation in the solution with the metal cation adsorption on negatively charged carbon surface in a single operation unit. The carbon/metals interaction at the surface of spent adsorbents is discussed.

  • 20.
    Makarova, T
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zakharova, IB
    Separation of intrinsic and extrinsic contribution to fullerene magnetism2008In: Fullerenes, nanotubes, and carbon nanostructures, Vol. 16, no 5, 567-573 p.Article in journal (Refereed)
    Abstract [en]

    Magnetic and structural properties of pressure-polymerized fullerenes have been systematically studied by means of magnetometry, electron spin resonance (ESR), X-ray diffractometry and Raman spectroscopy. For several samples, the magnetization values were higher than those expected from the metallic contamination. We followed in situ the depolymerization process through the temperature dependence of the ESR signal and observed simultaneous changes in the g-factor, Raman spectra and X-ray patterns. On cooling, the magnetization values of the depolymerized samples dropped several times. Thus, the magnetic signal is directly connected with the polymerized fullerene phase and cannot be attributed to iron compounds.

  • 21.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Ferromagnetic Carbon Nanostructures2008In: Progress in Industrial Mathematics at ECMI 2006 / [ed] Luis L. Bonilla, Miguel Moscoso, Gloria Platero, Jose M. Vega, Berlin, Heidelberg: Springer-Verlag Berlin Heidelberg , 2008, 467-476 p.Conference paper (Refereed)
  • 22.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Physics.
    Ferromagnetic carbonaceous compounds2006In: Carbon based magnetism: an overview of the magnetism of metal free carbon-based compounds amd materials, Elsevier Science , 2006, 541-562 p.Chapter in book (Other academic)
  • 23.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Fullerenes: magnetic behavior: Chapter 1202009In: Dekker encyclopedia of nanoscience and nanotechnology, Taylor & Francis, 2009, 2, 1352-1359 p.Chapter in book (Other academic)
  • 24.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Magnetic behaviour of polymerized fullerenes2004In: Dekker Encyclopedia of Nanoscience and Nanotechnology, New York: Marcel Dekker , 2004, 1655-1664 p.Chapter in book (Refereed)
  • 25.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Magnetic nanocarbon: Chapter 1712009In: Dekker encyclopedia of nanoscience and nanotechnology, Taylor & Francis, 2009, 2, 1939-1950 p.Chapter in book (Other academic)
  • 26.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Physics.
    Magnetic properties of carbon structures2004In: Semiconductors, Vol. 38, no 6, 615-638 p.Article, review/survey (Other (popular science, discussion, etc.))
  • 27.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Physics.
    Magnetism in polymerized fullerenes2004In: Journal of Magnetism and Magnetic Materials vol. 272-276, Suppl. 1, Elsevier , 2004, E1263-E1268 p.Conference paper (Refereed)
  • 28.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nanomagnetism in otherwise nonmagnetic materials2010In: Handbook of Nanophysics: Vol. 1. Principles and Methods / [ed] Sattler, Klaus D., Boca Raton, Fla.: Taylor and Francis , 2010, 25-30 p.Chapter in book (Other academic)
  • 29.
    Makarova, Tatiana
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Reproducible synthesis of magnetic carbon through ion implantation2011In: Solid State Phenomena, ISSN 1012-0394, Vol. 168-169, 505-513 p.Article in journal (Refereed)
    Abstract [en]

    Comparative study of magnetic properties of highly oriented pyrolytic graphite irradiatedwith different particles suggests that ions (H+, He+, C+) with the energy in the range of hundredskeV yield larger values of induced magnetization compared to the protons with the energy of severalMeV. These values increase with ion fluence but abruptly decrease when the concentration ofinterstitial defects becomes so large that the graphite stacking sequence is collapsed.

  • 30.
    Makarova, Tatiana L
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Han, K.-H.
    Umeå University, Faculty of Science and Technology, Physics.
    Esquinazi, P
    da Silva, R.R.
    Kopelevich, Yakov
    Zakharova, I.B.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Physics.
    Magnetism in photopolymerized fullerenes2003In: Carbon, ISSN 0008-6223, Vol. 41, no 8, 1575-1584 p.Article in journal (Refereed)
    Abstract [en]

    The phototransformation of bulk C-60 and laser- and electron-beam treatment of C-60 films in air changes their magnetic properties. Nonlinear magnetization is observed only for samples irradiated in the presence of oxygen, while, in the case of pressure-polymerized C-60, oxygen adversely affects the magnetic properties. The contrasting roles of oxygen in these processes are discussed. Magnetic force microscopy shows that laser- and electron-beam irradiation of fullerene films produces magnetic images which are highly correlated with the topographic images.

  • 31.
    Makarova, Tatiana L.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Kvyatkovskii, Oleg E.
    Zakharova, Irina B.
    Buga, Sergei G.
    Voklov, Aleksandr P.
    Shelankov, Andrei L.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Laser controlled magnetism in hydrogenated fullerene films2011In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 109, no 8, 083941-7 p.Article in journal (Refereed)
    Abstract [en]

    Room temperature ferromagnetic-like behavior in fullerene photopolymerized films treated with monatomic hydrogen is reported. The hydrogen treatment controllably varies the paramagnetic spin concentration and laser induced polymerization transforms the paramagnetic phase to a ferromagnetic-like one. Excess laser irradiation destroys magnetic ordering, presumably due to structural changes, which was continuously monitored by Raman spectroscopy. We suggest an interpretation of the data based on first-principles density-functional spin-unrestricted calculations which show that the excess spin from mono-atomic hydrogen is delocalized within the host fullerene and the laser-induced polymerization promotes spin exchange interaction and spin alignment in the polymerized phase.

  • 32.
    Makarova, Tatiana L.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Kvyatkovskii, Oleg E.
    Zakharova, Irina B.
    Buga, Sergei G.
    Volkov, Aleksandr P.
    Shelankov, Andrei L.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Response to "Comment on 'Laser controlled magnetism in hydrogenated fullerene films'" [J. Appl. Phys. 113, 036101 (2013)]2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 3, 036102- p.Article in journal (Other academic)
  • 33.
    Makarova, Tatiana L
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Liu, Bingbing
    Umeå University, Faculty of Science and Technology, Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Physics.
    AC susceptibility of some neutral C60 polymers2001In: Electronic Properties of Novel Materials - Science and Technology of Molecular Nanostructures: Proceedings of the XV International Winter School on Electronic Properties of Novel Materials, Kirchberg 2001, American Institute of Physics , 2001, 57-60 p.Conference paper (Refereed)
    Abstract [en]

    We have measured the temperature dependence of the magnetic susceptibility of photopolymerized and pressure-polymerized neutral C60 fullerenes. The data on C60 are diamagnetic. The observed magnetic response of both types of polymers is paramagnetic.

  • 34.
    Makarova, Tatiana L
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Scharff, Peter
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Physics.
    Narymbetov, B.
    Kobayashi, H.
    Tokumoto, M.
    Davydov, V.A.
    Rakhmanina, A.V.
    Kashevarova, L.S.
    Anisotropic metallic properties of highly-oriented rhombohedral C60 polymer.2001In: Synthetic Metals vol. 121: Proceedings of the International Conference on the Science and Technology of Synthetic Metals (ICSM2000), Gastein 2000, Amsterdam: Elsevier B.V. , 2001, 1099-1100 p.Conference paper (Refereed)
    Abstract [en]

    The pure rhombohedral phase of C60 polymer displays highly anisotropic electrical properties. Conductivity in the polymerized (001) planes exhibits a metal-insulator transition and shows the features of 2D weak localization. Anisotropy ratio is temperature-dependent and reaches 10_6. Dysonian ESR lineshape is consistent with the metallic nature of the samples.

  • 35.
    Makarova, Tatiana L.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Shelankov, Aandrei L.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Lyubchik, Svetlana B.
    Serenkov, Igor T.
    Sakharov, Vladimir I.
    Induced Ferromagnetism in Helium-Bombarded Graphite2012In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, Vol. 12, no 6, 5051-5053 p.Article in journal (Refereed)
    Abstract [en]

    Irradiation with helium ions is an effective method for triggering ferromagnetism in graphite. Chemical inertness of helium suggests that local magnetic moment formation is determined solely by the intrinsic carbon defects created during the target damage. Interacting moments are located in two places: in the vicinity of the sample surface and near the point of maximum defect generation.

  • 36.
    Makarova, Tatiana. L.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Shelankov, Andlei L.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Serenkov, I. T.
    Sakharov, V. I.
    Boukhwalov, D. W.
    Anisotropic magnetism of graphite irradiated with medium-energy hydrogen and helium ions2011In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 83, no 8, 085417-8 pages p.Article in journal (Refereed)
    Abstract [en]

    We have studied the changes in the magnetic behavior of highly oriented pyrolytic graphite (HOPG) samples subjected to medium-energy proton and helium irradiation. The variations of the ferromagneticlike magnetization curves with the irradiation dose have been studied for two configurations: magnetic fields parallel and perpendicular to graphitic planes. For high irradiation doses, the values of magnetization at saturation are close for both geometries. At low irradiation fluences an orientationally dependent magnetic response is obtained. Directional dependence of magnetization indicates that the magnetism in irradiated graphite is triggered by vertically aligned intrinsic carbon defects induced by irradiation. This physical picture has been verified by the observation of a local stray field near linear defects by means of magnetic force microscopy. Similar results obtained with hydrogen and helium ions confirm that the chemical nature of projectiles is not crucial for formation of ferromagnetic order in oriented graphite. The dependence of induced magnetic moment versus irradiation dose shows a maximum; the optimal dose is an order of magnitude less for helium ions than for protons, being in line with simulations showing that He+ generates 8 times more defects than H+. Raman studies indicate that the degradation of magnetic ordering at large irradiation doses occurs much earlier than graphite amorphization but coincides with the destruction of graphene sheet stacking.

  • 37.
    Makarova, Tatiana L
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Physics.
    Höhne, Roland
    Esquinazi, Pablo
    Kopelevich, Yakov
    Scharff, Peter
    Davydov, Valerii A.
    Kashevarova, Ludmila S.
    Rakhmaninova, Aleksandra V.
    Magnetic Carbon2001In: Nature, ISSN 0028-0836, Vol. 413, no 6857, 716-718 p.Article in journal (Refereed)
    Abstract [en]

    Paper retracted.

  • 38.
    Makarova, Tatiana L
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Physics.
    Kopelevich, Yakov
    Magnetism in C60 induced by polymerization2002In: Fullerenes vol. 12: The Exciting World of Nanocages and Nanotubes: Proceedings of the 201st ECS Meeting, Symposia V1-V9: Fullerenes, Nanotubes, and Carbon Nanoclusters, Pennington: The Electrochemical Society , 2002, 664-678 p.Conference paper (Refereed)
  • 39.
    Makarova, Tatiana L
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Physics.
    Kopelevich, Yakov
    Structural studies of magnetic polymerized fullerenes2003In: Synthetic Metals volume 137: Proceedings of the International Conference on Science and Technology of Synthetic Metals, Shanghai 2002, Amsterdam: Elsevier B.V. , 2003, 1335-1337 p.Conference paper (Refereed)
    Abstract [en]

    X-ray and Raman measurements have been performed on samples of polymerized fullerenes which show weak ferromagnetism. For pressure-polymerized fullerenes, ferromagnetic features are observed in a narrow temperature range very close to the limit of stability of the cages. Raman spectra show that the type of polymerization is probably of less importance. Strong structural inhomogeneity of the samples suggests that the magnetic phase forms a minority phase in a non-magnetic matrix.

  • 40.
    Makarova, Tatiana L
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Scharff, Peter
    Gaevski, M.E.
    Olsson, Eva
    Davydov, V.A.
    Rakhmanina, A.V.
    Kashevarova, L.S.
    Electrical properties of two-dimensional fullerene matrices2001In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 39, no 14, 2203-2209 p.Article in journal (Refereed)
    Abstract [en]

    The electrical properties of two-dimensionally polymerized C60 fullerenes were studied. Fullerene matrices consisting of randomly oriented domains are compared to the highly-oriented rhombohedral phase. The conductivity of the randomly oriented polymers obeys the Arrhenius law and can be described in a multiple trapping model. The oriented phase of polymeric C60 shows a distinct anisotropy in the electrical properties with a metallic-like in-plane conductivity at high temperatures.

  • 41.
    Makarova, Tatiana L
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Physics.
    Agafonov, V.
    Davydov, V.A.
    Rakhmanina, A.V.
    Kashevarova, L.S.
    Electrical properties of the rhombohedral C60 polymers1999In: Fullerenes: Recent Advances in the Chemistry and Physics of Fullerenes and Related Materials, vol. 7: Proceedings of the Symposium "Fullerenes: Chemistry, Physics, and New Directions XII", 195th Meeting of the Electrochemical Society, Seattle 1999, Pennington, NJ: The Electrochemical Society , 1999, 628-639 p.Conference paper (Refereed)
    Abstract [en]

    Electrical properties of polymerized fullerenes C60 are governed by the type of polymerization which is in turn determined by the initial (P or H) orientation of molecules, the pressure and the temperature of polymerization. The mixed tetragonal - rhombohedral polymerized structure shows a semiconductor-like behavior. An increase in the polymerization temperature results in a decrease in the activation energy and an increase in conductivity. The conductivity prefactor and the activation energy are interconnected by the Meyer-Neldel rule. The pure rhombohedral phase shows highly anisotropic electrical properties. The conductivity in the polymerized (111) planes exhibits a metal-insulator transition and shows the features of 2D weak localization.

  • 42.
    Makarova, Tatiana L
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zhu, Xiaomei
    Nyeanchi, Emmanuel B.
    Gaevski, M.E.
    Olsson, Eva
    Agafonov, V.
    Davydov, V.A.
    Rakhmaninova, A.V.
    Kashevarova, L.S.
    Conductivity of two-dimensional C60 polymers2000In: Proceedings of the 4th International Workshop on Fullerenes and Atomic Clusters (IWFAC'99), St. Petersburg 1999, Overseas Publishers Association N.V. , 2000, 151-156 p.Conference paper (Refereed)
    Abstract [en]

    The general trend in the shift of electronic properties as the result of polymerization has been studied with the aid of temperature dependences of conductivity. Samples representing the pure rhombohedral phase exhibit great anisotropy in their electrical properties. The main features of the behaviour of these samples are: (i) in the z-direction the resistivity is of the order of several kOhm cm and decreases with temperature; (ii) in the x-y direction resistivity is less than 1 Ohm cm and shows a minimum at a certain temperature.

  • 43.
    Makarova, Tatiana L
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zagaynova, Valeria
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Inan, G
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Okotrub, AV
    Chekhova, GN
    Pinakov, DV
    Bulusheva, LG
    Structural evolution and magnetic properties of underfluorinated C2F2012In: Journal of Superconductivity and Novel Magnetism, ISSN 1557-1939, Vol. 25, no 1, 79-83 p.Article in journal (Refereed)
    Abstract [en]

    A series of layered inclusion compounds based on fluorinated graphite C2F x (x≤1) was obtained by a room temperature synthesis. Inclusion compounds (intercalates) of fluorinated graphite matrix were n-hexane and dichloromethane, i.e., organic guest molecules that differ in size and symmetry. The changes in C2F x stoichiometry are shown to have a decisive effect on magnetic properties of produced complexes. The spin concentration decreases with the increase of fluorine content in fluorocarbon matrix. All samples have groups of correlated spins; at the temperatures 1.75–5 K nonlinear magnetization is observed, indicating a high-spin state. Application of the Langevin formula shows that the clusters consist of 10–20 interacting spins.

  • 44.
    Makarova, Tatiana L.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zakharova, I. B.
    State Polytechnical University, St Petersburg, Russia.
    Kvyatkovskii, O. E.
    Ioffe Physico-Technical Institute, St Petersburg, Russia.
    Buga, S. G.
    Technological Institute for Superhard and Novel Carbon Materials, Troitsk, Russia.
    Volkov, A. P.
    Technological Institute for Superhard and Novel Carbon Materials, Troitsk, Russia.
    Shelankov, Andrei L.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Experimental realization of high spin states in dilutely hydrogenated fullerenes2009In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 246, no 11-12, 2778-2781 p.Article in journal (Refereed)
    Abstract [en]

    A novel method for preparing dilutely hydrogenated fullerenes H:C60 is presented. DFT calculations of the Raman spectra at the B3LYP/3-21G level are compared with the experimental data. Under the laser treatment these phases form a rich variety of dimeric and polymeric structures, quite in contrast to pristine C60 which forms dimers and polymers bonded through the [2 + 2] addition, and in contrast to heavily hydrogenated fullerenes which do not polymerize at all. Dilutely hydrogenated fullerenes polymerize differently, forming both double bonded structures and single bonded dimers. We have shown that dilute hydrogenation of C60 creates large amount of unpaired spins which disappear due to the formation of diamagnetic single bonded dimers.

  • 45.
    Makarova, Tatiana
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Ricco, Mauro
    Pontiroli, Daniele
    Mazzani, Marcello
    Belli, Matteo
    Goffredi, Angelo
    Ageing effects in nanographite monitored by Raman spectroscopy2008In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 245, no 10, 2082-2085 p.Article in journal (Refereed)
    Abstract [en]

    The structural relaxation of nanographite ball-milled in argon atmosphere and stored in evacuated ampoules, has been studied by monitoring the evolution of the Raman spectra. Reduction of some Raman bands associated with “in-plane” structural defects, such as vacancies, dislocations or grain boundaries, and those associated with “out-of-plane” defects, such as stacking faults, is accompanied by the rise of new bands around 1180 and 2000 cm–1. The development of these bands is suppressed in nanographite samples exposed to a flux of pure anhydrous hydrogen.

  • 46.
    Makarova, Tatiana
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Shelankov, Andlei L.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Serenkov, Igor T.
    Sakharov, Vladimir I.
    Magnetism in graphite induced by irradiation of hydrogen and helium atoms: a comparative study2010In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 247, no 11-12, 2988-2991 p.Article in journal (Refereed)
    Abstract [en]

    To identify the origin of defect-induced magnetism in ion-irradiated graphite, a comparative study of samples of graphite irradiated with hydrogen H+ and helium He+ ions is performed. Directionally dependent magnetic properties, atomic/magnetic force microscopy studies suggest that the induced magnetic moments are located along the vertically aligned grain boundaries. Compared to the case of the hydrogen ion irradiation, the optimal helium irradiation dose is an order of magnitude lower. From this we conclude that the hydrogen chemistry is essentially irrelevant, and the ferromagnetic-like response of the irradiated graphite is due to structural defects regardless of their origin.

  • 47.
    Makarova, Tatiana
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Physics.
    Electrical and magnetic properties of undoped fullerene polymers2002In: Frontiers of Multifunctional Nanosystems: Proceedings of the NATO Advanced Research Workshop on Frontiers in Molecular-Scale Science and Technology of Fullerence, Nanotube, Nanosilicon, Biopolymer (DNA, Protein) Multifunctional Nanosystems, Kyiv, Ukraine, 9-12 September 2001, Dordrecht: Springer/Kluwer , 2002, 291-312 p.Conference paper (Refereed)
    Abstract [en]

    Carbon has a wide range of transport properties which are strongly dependent on the graphitic (sp(2)) to tetrahedral (Sp(3)) carbon bonding ratio, Fullerenes comprise the third class of pure carbon, after diamond and graphite. The conductivity of van der Waals fullerene solids is governed by a thermal activation mechanism. Polymerization modifies the band structure with a decrease of activation energy. At certain conditions a transition to a metallic behavior is observed experimentally. Polymerization of fullerenes also results in a transition from diamagnetic to paramagnetic behavior.

  • 48.
    Makarova, Tatiana
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Physics.
    Pressure-induced ferromagnetism of fullerenes2003In: High Pressure Research vol. 23, issues 1-3: Proceedings of the 40th European High Pressure Research Group Meeting on Advances in High Pressure Research, Edinburgh 2002, London: Taylor & Francis , 2003, 135-141 p.Conference paper (Refereed)
    Abstract [en]

    Ferromagnetic behavior of polymerized fullerenes appears quite close to the boundary where the fullerene molecules are destroyed. However, when the presence of a disordered or graphitic phase is detectable by the standard characterisation methods, the ferromagnetic features quickly disappear.

  • 49.
    Makarova, Tatiana
    et al.
    Umeå University.
    Vozmediano, M. A. H.
    Minisymposium "Ferromagnetic Carbon Nanostructures"2008In: Progress in Industrial Mathematics at ECMI 2006 / [ed] Luis L. Bonilla, Miguel Moscoso, Gloria Platero, Jose M. Vega, Berlin, Heidelberg: Springer-Verlag Berlin Heidelberg , 2008, 466-467 p.Conference paper (Other (popular science, discussion, etc.))
  • 50.
    Makarova, Tatiana
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zagaynova, Valeria
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Okotrub, AV
    Kurenya, AG
    Komogortsev, SV
    Bulusheva, LG
    Magnetic properties of carbon nanotubes with low content of Fe2010In: Fullerenes, nanotubes, and carbon nanostructures (Print), ISSN 1536-383X, E-ISSN 1536-4046, Vol. 18, no 4-6, 569-573 p.Article in journal (Refereed)
    Abstract [en]

    Films of oriented carbon nanotubes containing different concentrations of ferrocene (0.5%, 1%, 1.5%, 2%, 2.5% and 5%) have been synthesized by CVD method and studied by means of SQUID and force microscopy. Strong dependence of magnetization process on nanotubes parameters is observed. Magnetic anisotropy of low-doped nanotubes is shown to have an easy magnetic axis perpendicular to the aligned nanotubes.

12 1 - 50 of 68
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