Synthesis of cobalt nanowires in aqueous solution under an external magnetic field

• Xiaoyu Li,
• Lijuan Sun,
• Hu Wang,
• Kenan Xie,
• Qin Long,
• Xuefei Lai and
• Li Liao

Beilstein J. Nanotechnol. 2016, 7, 990–994, doi:10.3762/bjnano.7.91

• pressures, cobalt nanowires were synthesized by chemical reduction in aqueous solution with the assistance of polyvinylpyrrolidone (PVP) as surfactant under moderate conditions for the first time, while an external magnetic field of 40 mT was applied. Uniform linear cobalt nanowires with relatively smooth

• surfaces and firm structure were obtained and possessed an average diameter of about 100 nm with a coating layer of PVP. By comparison, the external magnetic field and PVP were proven to have a crucial influence on the morphology and the size of the synthesized cobalt nanowires. The prepared cobalt

• nanowires are crystalline and mainly consist of cobalt as well as a small amount of platinum. Magnetic measurements showed that the resultant cobalt nanowires were ferromagnetic at room temperature. The saturation magnetization (Ms) and the coercivity (Hc) were 112.00 emu/g and 352.87 Oe, respectively

Thickness dependence of the triplet spin-valve effect in superconductor–ferromagnet–ferromagnet heterostructures

• Daniel Lenk,
• Vladimir I. Zdravkov,
• Jan-Michael Kehrle,
• Günter Obermeier,
• Aladin Ullrich,
• Roman Morari,
• Hans-Albrecht Krug von Nidda,
• Claus Müller,
• Mikhail Yu. Kupriyanov,
• Anatolie S. Sidorenko,
• Siegfried Horn,
• Rafael G. Deminov,
• Lenar R. Tagirov and
• Reinhard Tidecks

Beilstein J. Nanotechnol. 2016, 7, 957–969, doi:10.3762/bjnano.7.88

• layer was sputtered from the same target as the metallic Co layer, however, oxygen gas was mixed into the chamber atmosphere to achieve reactive growth of cobalt oxide. For more details on the sputtering procedures see [8][9][41]. The heterostructure obtained was then cut perpendicular to the thickness

• values for the splitting of the metallic and oxide cobalt signals, cross-checked with the RBS spectra for plausibility and slightly adapted to yield the best fit to the RBS spectra. Furthermore, we conducted superconducting quantum interference device (SQUID) magnetometry investigations on several SF1NF2

Magnetic switching of nanoscale antidot lattices

• Ulf Wiedwald,
• Joachim Gräfe,
• Kristof M. Lebecki,
• Maxim Skripnik,
• Felix Haering,
• Gisela Schütz,
• Paul Ziemann,
• Eberhard Goering and
• Ulrich Nowak

Beilstein J. Nanotechnol. 2016, 7, 733–750, doi:10.3762/bjnano.7.65

• films (cf. Figure 5b). All materials show very similar trends. It is noticeable that Py exhibits the smallest coercive fields for all antidot diameters, while the coercive fields for Iron and Cobalt are approximately on the same level for antidot diameters below d = 95 nm. For larger antidots, the

Hemolysin coregulated protein 1 as a molecular gluing unit for the assembly of nanoparticle hybrid structures

• Tuan Anh Pham,
• Andreas Schreiber,
• Elena V. Sturm (née Rosseeva),
• Stefan Schiller and
• Helmut Cölfen

Beilstein J. Nanotechnol. 2016, 7, 351–363, doi:10.3762/bjnano.7.32

• gluing unit for the assembly of often linear, hybrid structures of plasmonic gold (Au NP), magnetite (Fe3O4 NP), and cobalt ferrite nanoparticles (CoFe2O4 NP). Furthermore, the assembly of Au NPs into linear structures using Hcp1_cys3 is investigated by UV–vis spectroscopy, TEM and cryo-TEM. One key

• Hcp1_cys3 as a connecting unit is extended to magnetite NPs (Fe3O4 NPs) and cobalt ferrite NPs (CoFe2O4 NPs). The synthesis of magnetite NPs with a size of about 8 nm and the ligand exchange followed the protocol of Cabrera et al. [36], with results as shown in the TEM images of Figure S4, Supporting

• the blank Fe3O4 NPs. A third NP system demonstrates that our concept of the utilization of Hcp1_cys3 as a gluing unit between the NPs to fabricate a linear structure is universal. We synthesized cobalt ferrite NPs (CoFe2O4 NPs) following the protocol of Cabrebra [36] and exchanged the oleic acid

Synthesis and applications of carbon nanomaterials for energy generation and storage

• Marco Notarianni,
• Jinzhang Liu,
• Kristy Vernon and
• Nunzio Motta

Beilstein J. Nanotechnol. 2016, 7, 149–196, doi:10.3762/bjnano.7.17

• metal catalyst such as cobalt [48]. The nanotubes are typically bound together by strong van der Waals interactions and form tight bundles. The second method, laser ablation, uses continuous wave [49] or pulsed [50] lasers to ablate a carbon target in a 1200 °C tube furnace. A laser beam evaporates a

• graphite sample containing 1% nickel and cobalt catalyst particles [51]. In the resulting vapor, the metal aggregates into carbon-saturated catalyst nanoparticles, which instigate the growth of CNTs [48]. These catalyst particles are necessary to produce SWNTs rather than MWNTs [52]. The relative amount of

• types, as well as the operating temperature [54]. The production of MWNTs typically involves ethylene or acetylene feedstock with an iron, nickel or cobalt catalyst and operating temperatures of 550–750 °C. SWNTs are produced by using methane or ethane feedstock, similar catalysts, and operating

Effects of spin–orbit coupling and many-body correlations in STM transport through copper phthalocyanine

• Benjamin Siegert,
• Andrea Donarini and
• Milena Grifoni

Beilstein J. Nanotechnol. 2015, 6, 2452–2462, doi:10.3762/bjnano.6.254

• enormous anisotropies in both spin and orbital dipole moments [9]. Furthermore, recent experimental findings for cobalt pththalocyanine in a scanning tunneling microscopy (STM) setup [10] suggest that many-body correlations play an important role in the interpretation of the transport measurements. In a

Self-assembly mechanism of Ni nanowires prepared with an external magnetic field

• Xiaoyu Li,
• Hu Wang,
• Kenan Xie,
• Qin Long,
• Xuefei Lai and
• Li Liao

Beilstein J. Nanotechnol. 2015, 6, 2123–2128, doi:10.3762/bjnano.6.217

• , electronic, sensor and electrochemical devices [1][2][3][4][5][6]. In particular, Ni nanowires have been the focus of intense research due to their easy preparation compared with iron and cobalt nanowires. There are several reported routes for the preparation of Ni nanowires including template-based

• cobalt nanowires using a gamma irradiation technique under an external magnetic field. Li et al. [15] synthesized nickel chains under a weak magnetic field by hydrazine reduction in ethylene glycol. Smooth Ni nanowires were prepared by Hu et al. [16] under a stronger magnetic field. Soumare et al. [17

• ][21] proposed a possible mechanism of self-assembly speculated from the morphology of nickel and cobalt nanowires. Meng et al. [22] proposed a similar mechanism. However, no related experiments were designed to prove their proposed self-assembly mechanism. Herein, Ni nanowires are synthesized in

Paramagnetism of cobalt-doped ZnO nanoparticles obtained by microwave solvothermal synthesis

• Jacek Wojnarowicz,
• Sylwia Kusnieruk,
• Tadeusz Chudoba,
• Stanislaw Gierlotka,
• Witold Lojkowski,
• Wojciech Knoff,
• Malgorzata I. Lukasiewicz,
• Bartlomiej S. Witkowski,
• Anna Wolska,
• Marcin T. Klepka,
• Tomasz Story and
• Marek Godlewski

Beilstein J. Nanotechnol. 2015, 6, 1957–1969, doi:10.3762/bjnano.6.200

• -142 Warsaw, Poland Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland 10.3762/bjnano.6.200 Abstract Zinc oxide nanopowders doped with 1–15 mol % cobalt were produced by the microwave solvothermal synthesis (MSS) technique. The obtained nanoparticles were

• , likely related to the precipitation of metallic Co in nanoparticles. Keywords: cobalt-doped zinc oxide; ferromagnetism; magnetic properties; microwave solvothermal synthesis (MSS); paramagnetism; Introduction Nanomaterials have drawn the attention of researchers from all over the world due to their new

• of the concentration of Co2+ ions in solution (nominal concentration) is shown in Figure 4 and Table 1. The actual doping level is approximately 10% lower than the Co concentration in the precursor solution. The difference between the theoretical and the measured concentration of cobalt in the Zn1

The role of low-energy electrons in focused electron beam induced deposition: four case studies of representative precursors

• Rachel M. Thorman,
• Ragesh Kumar T. P.,
• D. Howard Fairbrother and
• Oddur Ingólfsson

Beilstein J. Nanotechnol. 2015, 6, 1904–1926, doi:10.3762/bjnano.6.194

• to previously performed gas phase and surface studies of four organometallic FEBID precursors: trimethyl(methylcyclopentadienyl)platinum(IV) (MeCpPtMe3) [15][20][21], tetrakis(trifluorophosphine)platinum(0) (Pt(PF3)4) [13][14][22][23], cobalt tricarbonyl nitrosyl (Co(CO)3NO) [10][24][25] and tungsten

• . 4.3 Cobalt tricarbonyl nitrosyl; [Co(CO)3NO] and tungsten hexacarbonyl [W(CO)6] Cobalt tricarbonyl nitrosyl [Co(CO)3NO] was initially introduced in CVD as a liquid, easy-to-handle Co source. [76][77][78]. In CVD, Crawford et al. [78] reported an average composition of CoN0.5O0.9 with only traces of

• carbon when using Ar or N2 as carrier a gas at deposition temperatures below 380 °C. Above 400 °C, the authors found the deposits to consist of a mixture of CoO and Co metal. Deposition under hydrogen atmosphere, on the other hand, was found to result in pure cobalt deposits already at 350 °C [76][77

Predicting cytotoxicity of PAMAM dendrimers using molecular descriptors

• David E. Jones,
• Hamidreza Ghandehari and
• Julio C. Facelli

Beilstein J. Nanotechnol. 2015, 6, 1886–1896, doi:10.3762/bjnano.6.192

• techniques in this field. For instance, Liu et al. analyzed a number of attributes of a variety of nanoparticles in order to predict the 24 hour postfertilization mortality in zebrafish [3]. Horev-Azaria and colleagues used predictive modeling to explore the effect of cobalt–ferrite nanoparticles on the

Focused particle beam-induced processing

• Michael Huth and
• Armin Gölzhäuser

Beilstein J. Nanotechnol. 2015, 6, 1883–1885, doi:10.3762/bjnano.6.191

• on platinum [4]. The postprocessing of copper-based FEBID structures by vacuum annealing is presented by Aleksandra Szkudlarek and collaborators [5]. Additionally, high electric current densities can be used to induce structural changes in suspended nanowires, as is shown for cobalt deposits in the

• nanowires [7]. In the article by Oleksandr Dobrovolskiy and colleagues [8], different postgrowth purification treatments for platinum and cobalt FEBID structures are employed to fine-tune the magnetic properties of heterostructures. A novel application of electron beam-induced deposition of amorphous carbon

Radiation losses in the microwave K_u band in magneto-electric nanocomposites

• Talwinder Kaur,
• Sachin Kumar,
• Jyoti Sharma and
• A. K. Srivastava

Beilstein J. Nanotechnol. 2015, 6, 1700–1707, doi:10.3762/bjnano.6.173

• paper, we have used the versatile citrate precursor method to synthesize La–Co-substituted barium hexaferrite. Lanthanum and cobalt are used as substituents to enhance the magnetic properties of barium hexaferrite and then emulsion polymerization is employed for the synthesis of nanocomposites. The

The Kirkendall effect and nanoscience: hollow nanospheres and nanotubes

• Abdel-Aziz El Mel,
• Ryusuke Nakamura and
• Carla Bittencourt

Beilstein J. Nanotechnol. 2015, 6, 1348–1361, doi:10.3762/bjnano.6.139

• observation: symmetrical conversion mechanism The formation of hollow Kirkendall nanospheres was first reported by Yin et al. in 2004 [7]. They observed the formation of hollow nanospheres while exploring the sulfidation of cobalt nanoparticles by injecting a solution of sulfur in 1,2-dichlorobenzene into hot

• mechanism is the pioneering work of Yin et al. on the selenization of cobalt nanoparticles [7]. They have shown that the conversion reaction starts by the formation of a very thin cobalt selenide shell on the outer skin of the Co nanoparticle (Figure 3). As the reaction proceeds in time, the Co atoms tend

• to diffuse outward through the cobalt selenide shell until reaching the outer surface of the nanoparticle. Simultaneously, the Se atoms were reported to diffuse inward through the shell until reaching the Co core. Due to the high outward diffusion flux of Co compared to the slower inward flux of Se

Influence of the shape and surface oxidation in the magnetization reversal of thin iron nanowires grown by focused electron beam induced deposition

• Luis A. Rodríguez,
• Lorenz Deen,
• Rosa Córdoba,
• César Magén,
• Etienne Snoeck,
• Bert Koopmans and
• José M. De Teresa

Beilstein J. Nanotechnol. 2015, 6, 1319–1331, doi:10.3762/bjnano.6.136

• exciting research topic [1][2]. In this technique, a scanning electron microscope (SEM) dissociates the precursor molecules delivered into the area of interest by a gas-injection system, producing a deposit [3][4][5][6]. The use of precursor molecules containing cobalt [7][8][9][10] or iron [11][12][13][14

• producing the magnetization reversal. Most of magnetic devices work by producing a voltage output when the magnetization reversal occurs. In the case of cobalt deposits, it was previously found that the coercive field is governed by shape anisotropy [24] due to the polycrystalline microstructure [25], and

• is thus a function of the deposit dimensions [26]. However, more detailed studies subsequently emphasized the role played by the halo and the effective magnetic shape in the coercive field of cobalt nanowires [27][28][29]. In brief, the halo structure around the main deposit (caused by proximity

Structural transitions in electron beam deposited Co–carbonyl suspended nanowires at high electrical current densities

• Gian Carlo Gazzadi and
• Stefano Frabboni

Beilstein J. Nanotechnol. 2015, 6, 1298–1305, doi:10.3762/bjnano.6.134

• graphitized C. The breakdown current density is found at 2.1 × 107 A/cm2. The role played by resistive heating and electromigration in these transitions is discussed. Keywords: cobalt; electromigration; focused electron beam induced deposition (FEBID); metallic nanowires; Introduction The growing importance

• ) and third (111) most intense reflections of CoO FCC, suggests that such a phase is not present. This comparison indicates that the deposited material is a mixture of FCC (a larger fraction) and HCP cobalt nanograins. EDX analysis was also performed by TEM. The measured spectrum, in Figure 1c, shows

• resistivity obtained considering SNW 1 alone drops from 1.6 × 104 μΩ·cm, before the transition, to about 110 μΩ·cm, a value to be compared to 6 μΩ·cm for bulk cobalt. SEM inspection after this measurement shows no further difference from the picture in Figure 2b. TEM structural analysis after these electrical

Heterometal nanoparticles from Ru-based molecular clusters covalently anchored onto functionalized carbon nanotubes and nanofibers

• Deborah Vidick,
• Xiaoxing Ke,
• Michel Devillers,
• Claude Poleunis,
• Arnaud Delcorte,
• Pietro Moggi,
• Gustaaf Van Tendeloo and
• Sophie Hermans

Beilstein J. Nanotechnol. 2015, 6, 1287–1297, doi:10.3762/bjnano.6.133

• more expensive than iron, hence other alternatives such as cobalt were explored [49]. Zhenwei et al. have studied supported Ru–M (M = Fe, Co, Ni, Mo) with potassium as a promoter for ammonia synthesis [50]. They found that the Ru–Co catalysts have the highest activity, hence we incorporated this

Magnetic properties of iron cluster/chromium matrix nanocomposites

• Arne Fischer,
• Robert Kruk,
• Di Wang and
• Horst Hahn

Beilstein J. Nanotechnol. 2015, 6, 1158–1163, doi:10.3762/bjnano.6.117

• , and is usually accompanied by an increase of coercivity (Hc) and of the blocking temperature (TB). The EB was first described by Meiklejohn and Bean in 1956 [4]. They investigated clusters with a FM cobalt core and an AFM cobalt oxide (CoO) shell and consequently observed the characteristic horizontal

Charge carrier mobility and electronic properties of Al(Op)₃: impact of excimer formation

• Andrea Magri,
• Pascal Friederich,
• Bernhard Schäfer,
• Valeria Fattori,
• Xiangnan Sun,
• Timo Strunk,
• Velimir Meded,
• Luis E. Hueso,
• Wolfgang Wenzel and
• Mario Ruben

Beilstein J. Nanotechnol. 2015, 6, 1107–1115, doi:10.3762/bjnano.6.112

• additional electrons, and thus, Al(Op)3, should be characterized by both lower HOMO and LUMO energy levels as compared to Alq3. In a recent work, Al(Op)3 deposited on a magnetic cobalt substrate was investigated by means of ultraviolet photoemission spectroscopy (UPS) and near-threshold photoemission

• spectroscopy (NT-PS) [16]. The purpose was to study the spin-dependent properties of the Co/Al(Op)3 hybrid interface in comparison with the Co/Alq3 hybrid interface [17]. Due to the difference in the aromatic structures of Al(Op)3 and Alq3, which influences the chemisorption onto the cobalt substrate, it was

• calculated to be −5.93 eV, in fairly good agreement with the HOMO energy previously estimated by UPS on 1.5 and 5 nm films of Al(Op)3 deposited on cobalt which are −6.5 and −6.9 eV, respectively [16]. According to the same procedure, the HOMO–LUMO gap and the HOMO energy of Alq3 were estimated to be 2.82 and

High sensitivity and high resolution element 3D analysis by a combined SIMS–SPM instrument

• Yves Fleming and
• Tom Wirtz

Beilstein J. Nanotechnol. 2015, 6, 1091–1099, doi:10.3762/bjnano.6.110

• re-sputtered and extracted by the secondary optics of the mass spectrometer. Titanium carbonitride-based cermet The titanium carbonitride-based cermet consists of Ti(C,N) grains with a cobalt binder percolating the ceramic grains [21]. Figure 3 shows two snapshots of a Ti(C,N) sample analysed by

Tunable magnetism on the lateral mesoscale by post-processing of Co/Pt heterostructures

• Oleksandr V. Dobrovolskiy,
• Maksym Kompaniiets,
• Roland Sachser,
• Fabrizio Porrati,
• Christian Gspan,
• Harald Plank and
• Michael Huth

Beilstein J. Nanotechnol. 2015, 6, 1082–1090, doi:10.3762/bjnano.6.109

• hard-magnetic behavior for post-processed Co/Pt nano-stripes with coercive fields up to 850 Oe. We attribute the observed effects to the locally controlled formation of the CoPt L10 phase, whose presence has been revealed by transmission electron microscopy. Keywords: cobalt; focused electron beam

• . The employed purification procedure of heating at 300 °C in H2 atmosphere in conjunction with electron irradiation relies upon the Fischer–Tropsch reaction [30][43]. In this chemical process, cobalt serves as a catalyst, while volatile hydrocarbons and water are produced, effectively oxidizing the

Fabrication of high-resolution nanostructures of complex geometry by the single-spot nanolithography method

• Alexander Samardak,
• Margarita Anisimova,
• Aleksei Samardak and
• Alexey Ognev

Beilstein J. Nanotechnol. 2015, 6, 976–986, doi:10.3762/bjnano.6.101

• were sputtered with a magnetron in vacuum with a 20 nm-thick cobalt film. This resulted in 3D magnetic nanostructures with unusual spin configurations that potentially can be used in magnetic sensing technologies, memory, logic and biomedical applications [20]. Moreover, the single-spot nanolithography

Magnetic properties of self-organized Co dimer nanolines on Si/Ag(110)

• Lisa Michez,
• Kai Chen,
• Fabien Cheynis,
• Frédéric Leroy,
• Alain Ranguis,
• Haik Jamgotchian,
• Margrit Hanbücken and
• Laurence Masson

Beilstein J. Nanotechnol. 2015, 6, 777–784, doi:10.3762/bjnano.6.80

• edge, located at 779.4 eV. The XAS spectra, which clearly show no trace of cobalt silicides [30][31], are characteristic of metallic Co [32]. Such a lineshape has been seen in numerous structures composed of a thin Co layer grown on a metallic substrate [1][4][32][33][34] or an insulating support [35

Influence of gold, silver and gold–silver alloy nanoparticles on germ cell function and embryo development

• Ulrike Taylor,
• Daniela Tiedemann,
• Christoph Rehbock,
• Wilfried A. Kues,
• Stephan Barcikowski and
• Detlef Rath

Beilstein J. Nanotechnol. 2015, 6, 651–664, doi:10.3762/bjnano.6.66

•  3). A possible explanation might be that those agglomerates geometrically interfere with oocyte–sperm interactions. Interestingly, a study investigating the effect of silver, titatium dioxide and cobalt nanoparticles on sea urchin sperm observed no impact on sperm fertilising capability, but

Filling of carbon nanotubes and nanofibres

• Reece D. Gately and
• Marc in het Panhuis

Beilstein J. Nanotechnol. 2015, 6, 508–516, doi:10.3762/bjnano.6.53

• surface area (SSA, 1315 m2/g) [6] makes MWCNTs an ideal material for application in hydrogen storage [7], capacitors [8] and sensing [9]. Single-walled carbon nanotubes (SWCNTs) were discovered during investigations into the filling of MWCNTs with iron and cobalt [10][11]. Rather than producing a filled

• within the core of a filled MWCNT. This was achieved by first filling a MWCNT with iron, cobalt, nickel, or an iron–cobalt alloy using capillary action. Following this step, the sample was placed inside a transmission electron microscope (with the sample stage temperature set at 600 °C) and subjected to

Hematopoietic and mesenchymal stem cells: polymeric nanoparticle uptake and lineage differentiation

• Ivonne Brüstle,
• Thomas Simmet,
• Gerd Ulrich Nienhaus,
• Katharina Landfester and
• Volker Mailänder

Beilstein J. Nanotechnol. 2015, 6, 383–395, doi:10.3762/bjnano.6.38

• oxide with a dextran shell), no toxicity and normal differentiation behavior was shown for hHSCs [6][7][8]. A study with diverse inorganic nanoparticles of different sizes showed distinct toxicity for some particles (cobalt, antimony oxide) as well as some negative influence on the differentiation