Deposition of metal particles onto semiconductor nanorods using an ionic liquid

• Michael D. Ballentine,
• Elizabeth G. Embry,
• Marco A. Garcia and
• Lawrence J. Hill

Beilstein J. Nanotechnol. 2019, 10, 718–724, doi:10.3762/bjnano.10.71

• [bmim][Tf2N] without needing to add a sacrificial reducing agent. The chemical species oxidized during platinum reduction and deposition onto these nanorods in [bmim][Tf2N] is not known at this time, though others have observed similar results. CoPt nanoparticles were previously formed in [bmim][Tf2N

Investigation of growth dynamics of carbon nanotubes

• Marianna V. Kharlamova

Beilstein J. Nanotechnol. 2017, 8, 826–856, doi:10.3762/bjnano.8.85

• [116], CoMn [117], Ni [118], Fe [119][120], CoPt [121], CoxMg1−xO [122], CoSO4 [123], WCo alloy [124][125] and Mo2C [126]. SiO2 or MgO were used as catalyst support. The synthesis was conducted using different carbon precursors: CO [105][106][107][108][112][113][114][115][117][118][119][122][123

• in the nanotube diameters and broadening of the chirality distribution [106][109][110][112][115][117][121][122]. The (6,5) nanotube dominated in the samples synthesized at temperatures around 500–700 °C, whereas such selectivity disappeared at higher temperatures. In [121], a bimetallic CoPt catalyst

• was suggested for the selective growth of the (6,5) tubes at synthesis temperatures as high as 800–850 °C. The formation of CoPt alloy and its improved stability was suggested to be responsible for the selective growth of small diameter SWCNTs with a narrow chirality distribution. The authors of

Cubic chemically ordered FeRh and FeCo nanomagnets prepared by mass-selected low-energy cluster-beam deposition: a comparative study

• Veronique Dupuis,
• Anthony Robert,
• Arnaud Hillion,
• Ghassan Khadra,
• Nils Blanc,
• Damien Le Roy,
• Florent Tournus,
• Clement Albin,
• Olivier Boisron and
• Alexandre Tamion

Beilstein J. Nanotechnol. 2016, 7, 1850–1860, doi:10.3762/bjnano.7.177

• enlarges the Bragg–Dirac peak distribution expected only for infinite crystals. So for both systems, a the CsCl-type (B2) structure was assumed for the simulations by using the Debye formula as previously developed on mass-selected L10 CoPt nanoparticles with truncated-octahedron shape, as shown in Figure

• compatible with those of B2 FeRh bulk material with a Debye–Waller (DW) factor decreasing with chemical ordering. However, possibly due to relaxation effects at the nanoscale (as already observed in CoPt nanoalloys [31]), the DW parameter is still large upon annealing. This does not allow a perfect crystal

Peptide-equipped tobacco mosaic virus templates for selective and controllable biomineral deposition

• Klara Altintoprak,
• Axel Seidenstücker,
• Alexander Welle,
• Sabine Eiben,
• Petia Atanasova,
• Nina Stitz,
• Alfred Plettl,
• Joachim Bill,
• Hartmut Gliemann,
• Holger Jeske,
• Dirk Rothenstein,
• Fania Geiger and
• Christina Wege

Beilstein J. Nanotechnol. 2015, 6, 1399–1412, doi:10.3762/bjnano.6.145

• virus (TMV) were used as templates for coating with inorganic materials including Pt, Au [28], Ag [29][30], Pd [31][32], TiO2 [33], SiO2 [34], NiO [35], CdS [21], CoPt, FePt, ZnS [27][36] and ZnO [37][38][39]. Among the virus-based templates, plant viruses are especially suitable nanostructured

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

• for ultrahigh-density data-storage media. Thus, driven by the need to accomplish the above demand, FePt magnetic nanoparticles were prepared using colloidal chemistry [35] and micellar methods [36]. The latter method was also extended to the preparation of CoPt nanoparticles [37]. Later on, it turned

• the formation of the CoPt L10 phase with strongly increased magnetic anisotropy compared to pure Co. Here, we employ direct writing of Pt and Co layers by FEBID and demonstrate by means of in situ post-processing how to locally tune the coercive field and the remanent magnetization of layered Co/Pt

Synthesis, characterization, and growth simulations of Cu–Pt bimetallic nanoclusters

• Subarna Khanal,
• Ana Spitale,
• Nabraj Bhattarai,
• Daniel Bahena,
• J. Jesus Velazquez-Salazar,
• Sergio Mejía-Rosales,
• Marcelo M. Mariscal and
• Miguel José-Yacaman

Beilstein J. Nanotechnol. 2014, 5, 1371–1379, doi:10.3762/bjnano.5.150

• bimetallic (Pt–Co, Pt–Fe, Pt–Ni, Pt–Pd) nanocrystals with octahedral and cubic shape and examined their facet-dependent catalytic performance for the oxygen reduction reaction (ORR). Guo and co-workers [33] synthesized FePt and CoPt nanowires by organic-phase decomposition and demonstrated that these systems

Tuning the properties of magnetic thin films by interaction with periodic nanostructures

• Ulf Wiedwald,
• Felix Haering,
• Stefan Nau,
• Carsten Schulze,
• Herbert Schletter,
• Denys Makarov,
• Alfred Plettl,
• Karsten Kuepper,
• Manfred Albrecht,
• Johannes Boneberg and
• Paul Ziemann

Beilstein J. Nanotechnol. 2012, 3, 831–842, doi:10.3762/bjnano.3.93

• distances below 20 nm. In turn, hard magnetic alloys such as FePt or CoPt have to be used for smaller defect periods. Such a further reduction of size has been tested by self-assembly of 40 nm Au nanoparticles and subsequent deposition of Co/Pt multilayer films on top. Although magnetic exchange coupling

Focused electron beam induced deposition: A perspective

• Michael Huth,
• Fabrizio Porrati,
• Christian Schwalb,
• Marcel Winhold,
• Roland Sachser,
• Maja Dukic,
• Jonathan Adams and
• Georg Fantner

Beilstein J. Nanotechnol. 2012, 3, 597–619, doi:10.3762/bjnano.3.70

• to the next section. Co–Pt FEBID structures As a second example of a binary FEBID experiment recent results on the Co–Pt system are reviewed [33]. The binary phase diagram of Co–Pt features several ferromagnetic intermetallic compounds. The most prominent of these is the L10 phase of CoPt, which has

• at room temperature [13]. It would be desirable to also have access to hard-magnetic structures via the FEBID route. In this regard CoPt in the L10 phase represents an excellent choice. Experimental: The experiments were performed in a dual-beam microscope with Schottky electron emitter (FIB/SEM, FEI

• formed, which can be unequivocally attributed to the L10 intermetallic phase of CoPt, as detailed in Porrati et al. [33]. Magnetic and transport properties: Selected results from the electronic transport measurements comprising the temperature-dependent conductivity and the magnetic field dependence of

Spontaneous dissociation of Co₂(CO)₈ and autocatalytic growth of Co on SiO₂: A combined experimental and theoretical investigation

• Kaliappan Muthukumar,
• Harald O. Jeschke,
• Roser Valentí,
• Evgeniya Begun,
• Johannes Schwenk,
• Fabrizio Porrati and
• Michael Huth

Beilstein J. Nanotechnol. 2012, 3, 546–555, doi:10.3762/bjnano.3.63

• CoPt-C structures with CoPt nanocrystallites having the L10 crystal structure with hard-magnetic properties [17]. Also, it has been shown that, under well-controlled conditions, Co line structures with a width down to 30 nm are feasible [18][19]. These findings make FEBID with the Co-precursor

Nanoscaled alloy formation from self-assembled elemental Co nanoparticles on top of Pt films

• Luyang Han,
• Ulf Wiedwald,
• Johannes Biskupek,
• Kai Fauth,
• Ute Kaiser and
• Paul Ziemann

Beilstein J. Nanotechnol. 2011, 2, 473–485, doi:10.3762/bjnano.2.51

• Physik IV, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany 10.3762/bjnano.2.51 Abstract The thermally activated formation of nanoscale CoPt alloys was investigated, after deposition of self-assembled Co nanoparticles on textured Pt(111) and epitaxial Pt(100) films on MgO(100) and SrTiO3(100

• formation of a CoPt phase with strongly increased magnetic anisotropy compared to pure Co. At higher temperatures, however, the Co atoms diffuse into a nearby surface region where Pt-rich compounds are formed, as shown by element-specific microscopy. Keywords: alloy; Co; CoPt; epitaxy; HRTEM; magnetometry

• above requirements were presented by Sun et al. applying colloidal chemistry [9] and Ethirajan et al. using micellar methods [10]. Due to the higher variability of the micellar approach with respect to the interparticle distance, this technique has been continually improved and also extended to CoPt NPs

Effect of large mechanical stress on the magnetic properties of embedded Fe nanoparticles

• Srinivasa Saranu,
• Sören Selve,
• Ute Kaiser,
• Luyang Han,
• Ulf Wiedwald,
• Paul Ziemann and
• Ulrich Herr

Beilstein J. Nanotechnol. 2011, 2, 268–275, doi:10.3762/bjnano.2.31

• , Keff is the effective anisotropy energy density, V is the volume of the particle and kBT the thermal energy. The loss of stability can, in principle, be avoided by the use of materials with high coercivity [4], such as chemically ordered FePt or CoPt alloys. However, the use of such materials is

Structural and magnetic properties of ternary Fe_1–xMn_xPt nanoalloys from first principles

• Markus E. Gruner and
• Peter Entel

Beilstein J. Nanotechnol. 2011, 2, 162–172, doi:10.3762/bjnano.2.20

• the exponential and thus allows a very effective way of decreasing V [13][14]. The most promising materials in this respect are probably L10 ordered FePt and CoPt [7][13][15][16][17][18]. For these materials, hypothetical lower limits for the particle diameters can be derived from Equation (1) being

• greater in CoPt, the second candidate discussed in the introduction. Here, segregated core–shell structures are the dominating lowest energy morphologies for N = 561 being up to 120 meV/atom lower than the L10 ordered isomers. Also the aforementioned onion-ring structure turns out to be much more

• valence electron concentration e/a [58]. While the L11 phase is energetically lowest in CuPt, the L10 phase is clearly favored for CoPt and even more so for FePt and MnPt. On the other hand, recent surface energy calculations [55] have shown that L11 FePt and CoPt alloys possess extremely low surface

Kinetic lattice Monte-Carlo simulations on the ordering kinetics of free and supported FePt L1₀-nanoparticles

• Michael Müller and
• Karsten Albe

Beilstein J. Nanotechnol. 2011, 2, 40–46, doi:10.3762/bjnano.2.5

• ordered L10 structures like FePt and CoPt are considered as candidate materials for magnetic storage media [1] and biomedical applications [2] because the superparamagnetic limit – where a thermally stable magnetization direction can be expected – is in the range of a 5–10 nm. It has been shown

Flash laser annealing for controlling size and shape of magnetic alloy nanoparticles

• Damien Alloyeau,
• Christian Ricolleau,
• Cyril Langlois,
• Yann Le Bouar and
• Annick Loiseau

Beilstein J. Nanotechnol. 2010, 1, 55–59, doi:10.3762/bjnano.1.7

• ONERA / CNRS, BP 72, 92322 Châtillon Cedex, France 10.3762/bjnano.1.7 Abstract We propose an original route to prepare magnetic alloy nanoparticles with uniform size and shape by using nanosecond annealing under pulsed laser irradiation. As demonstrated here on CoPt nanoparticles, flash laser annealing

• ; nanosecond pulsed laser annealing; order-disorder transformation; Introduction Future high-density recording systems require 10 nm magnetic grains with a high magnetic anisotropy (Ku) to insure their thermal stability [1]. CoPt and FePt nanoparticles (NPs) in the chemically ordered L10 structure [2] are

• applications depend on the ability to synthesize NPs with a very good control over the size distribution and the chemical composition. Up to now, only chemical synthesis is able to produce monodisperse CoPt [6] and FePt [7][8] NPs with a polydispersity (that is, standard deviation divided by the mean size) as

Preparation and characterization of supported magnetic nanoparticles prepared by reverse micelles

• Ulf Wiedwald,
• Luyang Han,
• Johannes Biskupek,
• Ute Kaiser and
• Paul Ziemann

Beilstein J. Nanotechnol. 2010, 1, 24–47, doi:10.3762/bjnano.1.5

• Ulf Wiedwald Luyang Han Johannes Biskupek Ute Kaiser Paul Ziemann Institut für Festkörperphysik, Universität Ulm, 89069 Ulm, Germany Materialwissenschaftliche Elektronenmikroskopie, Universität Ulm, 89069 Ulm, Germany 10.3762/bjnano.1.5 Abstract Monatomic (Fe, Co) and bimetallic (FePt and CoPt

• found for CoPt nanoparticles (NPs). These results are related to imperfect crystal structures as revealed by HRTEM as well as to compositional distributions of the prepared particles. Interestingly, the results demonstrate that the averaged effective magnetic anisotropy of FePt nanoparticles does not

• strongly depend on size. Consequently, magnetization stability should scale linearly with the volume of the NPs and give rise to a critical value for stability at ambient temperature. Indeed, for diameters above 6 nm such stability is observed for the current FePt and CoPt NPs. Finally, the long-term

Preparation, properties and applications of magnetic nanoparticles

• Ulf Wiedwald and
• Paul Ziemann

Beilstein J. Nanotechnol. 2010, 1, 21–23, doi:10.3762/bjnano.1.4

• FePt or CoPt, which are well known for their high anisotropies, this approach should allow enhancing the related blocking temperatures significantly above ambient even for corresponding NPs with diameters of 3 nm if the particle anisotropy keeps its bulk value. In practice, however, that is exactly the