Diameter-driven crossover in resistive behaviour of heavily doped self-seeded germanium nanowires

• Stephen Connaughton,
• Maria Koleśnik-Gray,
• Richard Hobbs,
• Olan Lotty,
• Justin D. Holmes and
• Vojislav Krstić

Beilstein J. Nanotechnol. 2016, 7, 1284–1288, doi:10.3762/bjnano.7.119

• ]. To describe our findings, we first recall that in self-seeded Ge NWs the majority charge carriers are free holes whose concentration depends on the number of charge traps at the NW core/shell interface [11][18]. In particular, for larger diameter NWs those free holes will be predominantly located in

• coordinates [20][21] and for simplicity assuming a constant free-hole concentration nh. One finds the expression [22] where Φ0 is the electrostatic potential at the core/shell interface, ε0 is the vacuum permittivity, εr the dielectric constant of germanium, and e the elementary charge. The confinement of

• free holes into the space-charge region close to the NW surface only, however, cannot remain for all diameters. The available volume for the free holes and the number of charge-traps at the core/shell interface scale with NW diameter. Therefore, with decreasing diameter the holes will extend further

Mesoporous hollow carbon spheres for lithium–sulfur batteries: distribution of sulfur and electrochemical performance

• Anika C. Juhl,
• Artur Schneider,
• Boris Ufer,
• Torsten Brezesinski,
• Jürgen Janek and
• Michael Fröba

Beilstein J. Nanotechnol. 2016, 7, 1229–1240, doi:10.3762/bjnano.7.114

• mg·cm−2 was investigated. Results and Discussion Silica template and hollow carbon spheres Hollow carbon spheres with a mesoporous shell were obtained by impregnation of silica spheres with a core–shell structure with phenol and formaldehyde (first step in Figure 1). Carbonization under inert atmosphere

• [35]. In the second step a mesoporous shell was grown on the spheres by employing tetraethyl orthosilicate in presence of cetyltrimethylammonium bromide (CTAB) as a structure-directing agent. Combustion of CTAB in air generated the core–shell silica spheres. The diameter of the solid core was

• determined to be 380 nm by dynamic light scattering, while the diameter of the core–shell particles was about 515 nm. From SEM images (Figure S1 in Supporting Information File 1) a diameter of about 490 nm was determined for the core–shell spheres. Further characterization of the SCMS silica can be found in

Development of highly faceted reduced graphene oxide-coated copper oxide and copper nanoparticles on a copper foil surface

• Rebeca Ortega-Amaya,
• Yasuhiro Matsumoto,
• Andrés M. Espinoza-Rivas,
• Manuel A. Pérez-Guzmán and
• Mauricio Ortega-López

Beilstein J. Nanotechnol. 2016, 7, 1010–1017, doi:10.3762/bjnano.7.93

• the particle size and shape strongly depend on the process temperature. Characterization with transmission electron microscopy and scanning electron microscopy indicates that Cu or Cu2O nanoparticles take rGO sheets from the rGO network to form core–shell Cu–rGO or Cu2O–rGO nanostructures. It is noted

• ; copper(II) oxide; core–shell; reduced graphene oxide; Introduction In the last years, graphene oxide (GO) and reduced graphene oxide (rGO) have emerged as suitable candidates to prepare graphene-based nanocomposites [1][2], including those based on GO/inorganic nanoparticles [3]. The opportunity to

• or metal oxide nanoparticles [11]. In particular, rGO–Cu core–shell nanostructures have been synthesized by CVD [12][13], hydrothermal synthesis [14] and pyrolysis of an organocopper compound [15][16][17]. In a previous work, the authors reported the effective reduction of chemically exfoliated GO

Selective photocatalytic reduction of CO₂ to methanol in CuO-loaded NaTaO₃ nanocubes in isopropanol

• Tianyu Xiang,
• Feng Xin,
• Jingshuai Chen,
• Yuwen Wang,
• Xiaohong Yin and
• Xiao Shao

Beilstein J. Nanotechnol. 2016, 7, 776–783, doi:10.3762/bjnano.7.69

• irradiation at 25 °C. Ru-Shi Liu and co-workers [19] prepared a series of nanostructured core–shell materials (Ni@NiO/N-doped InTaO4 photocatalysts) for the reduction of CO2 to methanol in pure water. In these structures, the core–shell nanostructure might offer a new reaction center transferred from the

Early breast cancer screening using iron/iron oxide-based nanoplatforms with sub-femtomolar limits of detection

• Dinusha N. Udukala,
• Hongwang Wang,
• Sebastian O. Wendel,
• Aruni P. Malalasekera,
• Thilani N. Samarakoon,
• Asanka S. Yapa,
• Gayani Abayaweera,
• Matthew T. Basel,
• Pamela Maynez,
• Raquel Ortega,
• Yubisela Toledo,
• Leonie Bossmann,
• Colette Robinson,
• Katharine E. Janik,
• Olga B. Koper,
• Ping Li,
• Massoud Motamedi,
• Daniel A. Higgins,
• Gary Gadbury,
• Gaohong Zhu,
• Deryl L. Troyer and
• Stefan H. Bossmann

Beilstein J. Nanotechnol. 2016, 7, 364–373, doi:10.3762/bjnano.7.33

• is a vital strategy for early cancer detection. Water-dispersable Fe/Fe3O4-core/shell based nanoplatforms for protease detection are capable of detecting protease activity down to sub-femtomolar limits of detection. They feature one dye (tetrakis(carboxyphenyl)porphyrin (TCPP)) that is tethered to

• of detecting protease activities over a wide activity range down to sub-femtomolar LOD’s. These nanoplatforms consist of dopamine-covered, water-dispersable iron/iron oxide core/shell nanoparticles, to which one fluorescent dye (TCPP, tetrakis(carboxyphenyl)porphyrin) is tethered via a consensus

• central core/shell nanoparticle. For these specific consensus sequences, this effect exceeds the quenching effects (SET and FRET). Therefore, these two nanoplatforms show decreases of TCPP fluorescence upon cleavage. However, this decrease can still be utilized to measure the activities of uPA and MMP 9

Hydration of magnesia cubes: a helium ion microscopy study

• Ruth Schwaiger,
• Johannes Schneider,
• Gilles R. Bourret and
• Oliver Diwald

Beilstein J. Nanotechnol. 2016, 7, 302–309, doi:10.3762/bjnano.7.28

• , the MgO cubes have expanded presumably due to the formation of MgO/Mg(OH)2 core–shell structures, and a thick Mg(OH)2 layer coats the MgO cubes, leading to a partial fusion of the particles. As shown in Figure 3, the expansion of the MgO cubes is significant. We measured an average edge length

• substrate for imaging. Depending on their size the MgO-based cubes [21] become subject to significant volume expansion effects (up to a factor of 2.5) that are attributed to oxide transformation into hydroxides and the generation MgO/Mg(OH)2 core–shell structures as a result of the Kirkendall effect. These

Case studies on the formation of chalcogenide self-assembled monolayers on surfaces and dissociative processes

• Yongfeng Tong,
• Tingming Jiang,
• Azzedine Bendounan,
• Makri Nimbegondi Kotresh Harish,
• Angelo Giglia,
• Stefan Kubsky,
• Fausto Sirotti,
• Luca Pasquali,
• Srinivasan Sampath and
• Vladimir A. Esaulov

Beilstein J. Nanotechnol. 2016, 7, 263–277, doi:10.3762/bjnano.7.24

• chalcogenized interface layer on which molecules are then adsorbed. One can expect that capping nanoparticles with these molecules would lead to formation of metal–metal chalcogenide, core/shell nanoparticles, which has been shown to have interesting specific properties. In the case of chalcogenophene molecules

pH-Triggered release from surface-modified poly(lactic-co-glycolic acid) nanoparticles

• Manuel Häuser,
• Klaus Langer and
• Monika Schönhoff

Beilstein J. Nanotechnol. 2015, 6, 2504–2512, doi:10.3762/bjnano.6.260

• . We present here the idea of a two-step delivery system consisting of core–shell nanoparticles. The outer shell is susceptible to changes of the pH value, such that the release of a membrane-toxic cationic compound is triggered by a reduced pH value in the endolysosomal compartment of the cells. The

Surface-enhanced Raman scattering by colloidal CdSe nanocrystal submonolayers fabricated by the Langmuir–Blodgett technique

• Alexander G. Milekhin,
• Larisa L. Sveshnikova,
• Tatyana A. Duda,
• Ekaterina E. Rodyakina,
• Volodymyr M. Dzhagan,
• Ovidiu D. Gordan,
• Sergey L. Veber,
• Cameliu Himcinschi,
• Alexander V. Latyshev and
• Dietrich R. T. Zahn

Beilstein J. Nanotechnol. 2015, 6, 2388–2395, doi:10.3762/bjnano.6.245

• previously observed for several CdSe-based NCs, including pure CdSe and core–shell CdSe/CdZnS NCs deposited on Au or Ag substrates of various morphology [20][21][22][23]. Resonant SERS enables the observation of LO phonon modes of the CdSe core in a monolayer of core–shell CdSe/ZnS NCs deposited on

Silica-coated upconversion lanthanide nanoparticles: The effect of crystal design on morphology, structure and optical properties

• Uliana Kostiv,
• Miroslav Šlouf,
• Hana Macková,
• Alexander Zhigunov,
• Hana Engstová,
• Katarína Smolková,
• Petr Ježek and
• Daniel Horák

Beilstein J. Nanotechnol. 2015, 6, 2290–2299, doi:10.3762/bjnano.6.235

• . Compared with the initial 10 nm OM–NaYF4:Yb3+/Er3+ nanoparticles, the TEM micrograph (Figure 9) showed that the size of the NaYF4:Yb3+/Er3+&SiO2 particles had increased to 17 nm due to the presence of the silica shell on the surface. The NaYF4:Yb3+/Er3+&SiO2 nanoparticles had a clear core–shell structure

Mapping bound plasmon propagation on a nanoscale stripe waveguide using quantum dots: influence of spacer layer thickness

• Chamanei S. Perera,
• Alison M. Funston,
• Han-Hao Cheng and
• Kristy C. Vernon

Beilstein J. Nanotechnol. 2015, 6, 2046–2051, doi:10.3762/bjnano.6.208

• an emission wavelength of 655 nm were obtained from invitrogen (Cat. No: Q21321MP). These carboxyl QDs are made from CdSe nanocrystals shelled with a ZnS layer. The core–shell material is further coated with a polymer layer to allow for better dispersion of the QDs in aqueous solution. These QDs have

Simulation of thermal stress and buckling instability in Si/Ge and Ge/Si core/shell nanowires

• Suvankar Das,
• Amitava Moitra,
• Mishreyee Bhattacharya and
• Amlan Dutta

Beilstein J. Nanotechnol. 2015, 6, 1970–1977, doi:10.3762/bjnano.6.201

• employs the method of atomistic simulation to estimate the thermal stress experienced by Si/Ge and Ge/Si, ultrathin, core/shell nanowires with fixed ends. The underlying technique involves the computation of Young’s modulus and the linear coefficient of thermal expansion through separate simulations

• proposed methodology can be extended to other materials and structures and helps with the prediction of the conditions under which a nanowire-based device might possibly fail due to elastic instability. Keywords: atomistic simulation; buckling; core–shell nanowire; thermal stress; Introduction In recent

• years, a drastic rise in the research activities on semiconductor core/shell nanowires (CSNWs) made of silicon and germanium has occurred. Such studies are often motivated by the excellent charge transport properties of the materials [1][2][3][4], for which they are now seen as prospective candidates

Nanofibers for drug delivery – incorporation and release of model molecules, influence of molecular weight and polymer structure

• Jakub Hrib,
• Jakub Sirc,
• Radka Hobzova,
• Zuzana Hampejsova,
• Zuzana Bosakova,
• Marcela Munzarova and
• Jiri Michalek

Beilstein J. Nanotechnol. 2015, 6, 1939–1945, doi:10.3762/bjnano.6.198

• the materials enables to control the final structure of the prepared materials [6][20]. Generally, nanofibers that carry drugs follow several basic designs – nanofibers with homogenous structures in which the drug is dispersed throughout the polymer matrix, core–shell nanofibers for which the matrix

• primary factors that affect the diffusion mechanism and drug release. For homogenous nanofibers, the rate of release decreases with time, because the drug must travel progressively longer distances to diffuse to the fiber periphery, which requires more time. Contrary, the core–shell design provides the

A facile method for the preparation of bifunctional Mn:ZnS/ZnS/Fe₃O₄ magnetic and fluorescent nanocrystals

• Houcine Labiadh,
• Tahar Ben Chaabane,
• Romain Sibille,
• Lavinia Balan and
• Raphaël Schneider

Beilstein J. Nanotechnol. 2015, 6, 1743–1751, doi:10.3762/bjnano.6.178

• , 54001 Nancy Cedex, France 10.3762/bjnano.6.178 Abstract Bifunctional magnetic and fluorescent core/shell/shell Mn:ZnS/ZnS/Fe3O4 nanocrystals were synthesized in a basic aqueous solution using 3-mercaptopropionic acid (MPA) as a capping ligand. The structural and optical properties of the

• diodes [6][7] or solar cells [8]. Conventional QDs systems have a core/shell architecture. The shell, generally constituted of a wide band gap material such as ZnS, prevents degradation and preserves the optical properties [3][4]. Magnetic nanoparticles have many advantages, especially for biological

• shell (CdSe or CdS) of thickness between 2–7 nm resulting in either spherical core/shell nanoparticles or heterodimers [20][21][22]. The PL QY of the resulting bifunctional nanoparticles is generally low (typically <5%) due to the quenching effect of the magnetic domain [20][21]. Herein, we describe a

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

• range and their properties become different from those of the bulk material [38]. Surface features Transmission electron microscopy (TEM) has been used to determine the distribution and morphology of hexaferrite nanoparticles and polymer. A clear picture of a core–shell morphology can be seen in the TEM

Synthesis, characterization and in vitro biocompatibility study of Au/TMC/Fe₃O₄ nanocomposites as a promising, nontoxic system for biomedical applications

• Hanieh Shirazi,
• Maryam Daneshpour,
• Soheila Kashanian and
• Kobra Omidfar

Beilstein J. Nanotechnol. 2015, 6, 1677–1689, doi:10.3762/bjnano.6.170

• synthesize and optimize a combined nanocomposite containing both. By using various polymers such as chitosan, some of the problems of classic core–shell structures (such as reduced saturation magnetization and thick coating) have been overcome. In the present study, chitosan and one of its well-known

• steps, it is possible to prepare Au nanoparticles of different sizes and shapes that will enhance their efficacy and usage in different applications [33]. It is expected that the nanocomposites developed herein will have advantages over other hybrid Fe3O4 and gold core–shell structures. This is

• derivatives, TMC. This system not only takes advantage of the combined useful properties of both Fe3O4 and Au nanoparticles, but also has promising characteristics that resolve many of the previously reported shortcomings of classic core–shell structures [34]. Fe3O4 nanoparticles as the magnetic core Among

Structural and magnetic properties of iron nanowires and iron nanoparticles fabricated through a reduction reaction

• Marcin Krajewski,
• Wei Syuan Lin,
• Hong Ming Lin,
• Katarzyna Brzozka,
• Sabina Lewinska,
• Natalia Nedelko,
• Anna Slawska-Waniewska,
• Jolanta Borysiuk and
• Dariusz Wasik

Beilstein J. Nanotechnol. 2015, 6, 1652–1660, doi:10.3762/bjnano.6.167

• nanoparticles reveal core–shell structures and they are composed of crystalline iron cores that are covered by amorphous or highly defected phases of iron and iron oxides. Magnetic properties have been measured using a vibrating sample magnetometer. The obtained values of coercivity, remanent magnetization

• . Both nanomaterials reveal core–shell structures and are constructed of crystalline α-Fe cores, which are covered by a layered structure composed of: amorphous iron, amorphous iron oxides and distorted iron oxides (the layer order from core to surface). Additionally, iron nanowires are built from the

Thermal treatment of magnetite nanoparticles

• Beata Kalska-Szostko,
• Urszula Wykowska,
• Dariusz Satula and
• Per Nordblad

Beilstein J. Nanotechnol. 2015, 6, 1385–1396, doi:10.3762/bjnano.6.143

• and crystallinity, which in turn, was reflected in their thermal durability. The particles were obtained by coprecipitation from Fe chlorides and decomposition of an Fe(acac)3 complex with and without a core–shell structure. Three types of ferrite nanoparticles were produced and their thermal

• analysis of the magnetite and core–shell nanoparticles was performed on a Mettler Toledo differential scanning calorimeter (DSC). A Quantum Design MPMS SQUID magnetometer was used for the magnetization measurements. Mössbauer spectra (MS) were obtained using a conventional spectrometer working in constant

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

• , the oxidation process started with the formation of a thin layer of bismuth oxide on the outer skin of the bismuth nanoparticle (Figure 7a). An off-centered, single void was then formed at the bismuth/bismuth oxide core/shell interface. As the oxidation process proceeds in time, the void was found to

• a solid state reaction, occurring upon thermal annealing of core–shell ZnO/Al2O3 nanowires [23][62]. In such a process, the material forming the nanotube is defined by the two initial compounds constituting the core and the shell. As it can be seen in Figure 8, the formation of voids occurs at the

• on the outer skin of the metal nanowire resulting in the formation of a thin layer of metal oxide (Figure 9a). After the formation of a metal/metal oxide core/shell nanowire, the metal ions diffuse outward through the oxide layer until reaching the outer surface. Simultaneously, the oxygen adsorbed

Growth and morphological analysis of segmented AuAg alloy nanowires created by pulsed electrodeposition in ion-track etched membranes

• Ina Schubert,
• Loic Burr,
• Christina Trautmann and
• Maria Eugenia Toimil-Molares

Beilstein J. Nanotechnol. 2015, 6, 1272–1280, doi:10.3762/bjnano.6.131

• currently being intensively investigated. It has become evident that the combination of several materials in one nanostructure gives rise to specific functionalities that are not exhibited by the individual single components [1][2][3][4]. Different types of heterostructures such as core–shell, axially

• enhanced sensing resolution compared to pure Au nanowires [35] while Au@Ag core shell nanorods allow to adjust the resonance frequency by varying the shell thickness [36]. Furthermore, optical applications include the readout of striping patterns in AuAg segmented nanowires via optical brightfield

Addition of Zn during the phosphine-based synthesis of indium phospide quantum dots: doping and surface passivation

• Natalia E. Mordvinova,
• Alexander A. Vinokurov,
• Oleg I. Lebedev,
• Tatiana A. Kuznetsova and
• Sergey G. Dorofeev

Beilstein J. Nanotechnol. 2015, 6, 1237–1246, doi:10.3762/bjnano.6.127

• luminescence quantum yield through the reduction of phosphorous dangling bonds. A scenario for the growth of the colloidal InP(Zn) QDs was proposed and discussed. Keywords: core–shell nanoparticles; doped semiconductor nanocrystals; InP(Zn) quantum dots; luminescence; zinc; Introduction Colloidal quantum

• . In the low-magnification HAADF-STEM image (Figure 4a), the size of the QDs is close to that of the bright-field TEM images (Figure 3). However, upon close inspection using high resolution HAADF-STEM (Figure 4b–g), the core–shell structure of Zn/InP QDs can be clearly distinguished and confirmed. The

• particles in Figure 4b–g definitely exhibit a core–shell structure with a core diameter approximately about 2 nm, with mainly {111}-type surface facets (Figure 4b,d,f). The shape of the majority of the NPs is almost spherical. However, some of the NPs exhibit an elongated shape (Figure 4e,g). The core of

Synthesis, characterization and in vitro effects of 7 nm alloyed silver–gold nanoparticles

• Simon Ristig,
• Svitlana Chernousova,
• Wolfgang Meyer-Zaika and
• Matthias Epple

Beilstein J. Nanotechnol. 2015, 6, 1212–1220, doi:10.3762/bjnano.6.124

• resonance peak shows one maximum due to the distribution of the metals throughout the whole particle. Core–shell nanoparticles or individual silver or gold nanoparticles show two distinct plasmon resonance peaks [21][36][37]. As it is depicted in Figure 3, the absorption spectra show only one narrow peak

• obtained from the standard synthesis protocol are shown. The trend is almost linear, suggesting a good homogeneity of the alloyed metals, although some gradient in the composition within the nanoparticle cannot be ruled out. However, a core–shell structure with distinct, separate silver and gold regions

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

• shift of the hysteresis loops recorded after field cooling the samples from temperatures above the Néel temperature (TN) of CoO. Since its discovery the EB has been observed in numerous FM/AFM combinations such as core/shell clusters [5][6], thin film systems [7][8] and also cluster/matrix combinations

• ·nm−1. This straightforward relation between Heb and R of the embedded clusters has never been shown to that degree in any FM/AFM cluster/matrix system. As a comparison, one can look at the closely related core/shell nanoparticles featuring a FM core and an AFM shell. In that case a theoretical study

Interaction of electromagnetic radiation in the 20–200 GHz frequency range with arrays of carbon nanotubes with ferromagnetic nanoparticles

• Agylych Atdayev,
• Alexander L. Danilyuk and
• Serghej L. Prischepa

Beilstein J. Nanotechnol. 2015, 6, 1056–1064, doi:10.3762/bjnano.6.106

• (CNT) is considered within the model of distributed random nanoparticles with a core–shell morphology. The approach is based on a system composed of a CNT conducting resistive matrix, ferromagnetic inductive nanoparticles and the capacitive interface between the CNT matrix and the nanoparticles, which

From lithium to sodium: cell chemistry of room temperature sodium–air and sodium–sulfur batteries

• Philipp Adelhelm,
• Pascal Hartmann,
• Conrad L. Bender,
• Martin Busche,
• Christine Eufinger and
• Juergen Janek

Beilstein J. Nanotechnol. 2015, 6, 1016–1055, doi:10.3762/bjnano.6.105