Properties Of Novel Nanostructures Research Articles

Stress‐Induced Structural Phase Transition in Polystyrene/NaYF4: Eu3+ Photoluminescent Electrospun Nanofibers

Polystyrene (PS) composite nanofibers were successfully fabricated by embedding NaYF4: Eu3+ nanophosphor into the PS matrix via electrospinning. The photoluminescence spectra, surface morphology and crystal structure of nanofibers were characterized by photoluminescence spectroscopy, scanning electron microscopy, and X‐ray diffractometer, respectively. Stress‐induced α‐NaYF4: Eu3+ (cubic) to β‐NaYF4: Eu3+(hexagonal) structural phase transformation was observed in the nanofibers. The stress‐induced phase transformation provides enough space for tailoring the properties of novel nanostructures. The composite nanofibers exhibited blue emission with 239 nm excitation wavelength. The XRD pattern of espun nanofibers confirmed the successful incorporation of 5% NaYF4: Eu3+ nanophosphors into the PS matrix. Brilliant values of the chromaticity coordinates of the prepared photoluminescent nanofibers (PLNs) predict their possible use in blue solid‐state lighting applications.

Linear scaling approach for atomistic calculation of excitonic properties of 10-million-atom nanostructures

Numerical calculations of excitonic properties of novel nanostructures, such as nanowire and crystal phase quantum dots, must combine atomistic accuracy with an approachable computational complexity. The key difficulty comes from the fact that excitonic spectra details arise from atomicscale contributions that must be integrated over a large spatial domain containing a million and more of atoms. In this work we present a step-by-step solution to this problem: combined empirical tight-binding and configuration interaction scheme that unites linearly scaling computational time with the essentials of the atomistic modeling. We benchmark our method on the example of wellstudied self-assembled InAs/GaAs quantum dot. Next, we apply our atomistic approach to crystal phase quantum dots containing more than 10 million atoms.

Mechanical properties of hybrid boron nitride–carbon nanotubes

Hybrid boron nitride–carbon nanotubes (BN-CNTs) have attracted considerable attention in recent research. In this effort, molecular dynamics simulations were performed to study the fundamentals of BN-CNTs in tensile tests, i.e. Young’s modulus and fracture strength (strain). Particular attention was paid to the influence of the atomic structure, hybrid style, and BN concentration on the tensile properties. The morphological changes were also investigated for the BN-CNTs at the onset of fracture. It is noted that the Young’s modulus of BN-CNTs decreases almost linearly with increasing the BN concentration with a rate of change independent of the hybrid style. In contrast, the sensitivity of the fracture strength and fracture strain to the variation of BN concentration depends strongly on the hybrid style of BN-CNTs. These results are expected to significantly expand the knowledge of the elastic and fracture properties of novel nanostructures and facilitate their applications in bandgap-engineering.

Special issue: Electronic Properties of Novel Nanostructures

AbstractThis special issue of physica status solidi (b) contains contributions presented at the International Winterschool/Euroconference on Electronic Properties of Novel Materials (IWEPNM 2007). The meeting was held in March 2007 in Kirchberg, Austria.The articles in this issue provide essential information on a wide spectrum of topics, including quantum information, Raman spectroscopy and optics of nanotubes, synthesis of carbon nanotubes, carbon nanotubes and DNA, graphite and graphene, electron and heat transport in carbon nanostructures, composites with carbon nanotubes, as well as on theory and applications of these materials.As in previous years, the meeting was attended by many outstanding researchers from around the world and from a wide spectrum of scientific disciplines. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Special issue: Electronic Properties of Novel Nanostructures

AbstractThis special issue of physica status solidi (b) contains contributions presented at the International Winterschool/Euroconference on Electronic Properties of Novel Materials (IWEPNM 2006). The twentieth anniversary meeting was held in March 2006 in Kirchberg, Austria.The articles in this issue provide essential information on a wide spectrum of topics, including mechanical and electronic properties of carbon nanotubes, graphene, fullerenes and fulleroides, ab initio calculations for molecular nanostructures, single molecule experiments, scanning electron microscopy of molecular nanostructures, applications, composites and chemistry of molecular nanostructures, molecular machines and molecular motors, and template grown molecular nanomaterials.As in previous years, the meeting was attended by many outstanding researchers from around the world and from a wide spectrum of scientific disciplines. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Syntheses, characterization and properties of novel nanostructures consisting of Ni/titanate and Ni/titania

Ni/titanate one-dimensional nanostructures and Ni/titania nanocrystal composites were produced by a facile synthetic procedure using protonic titanate nanotubes as the precursor templates. The formation mechanisms for the nanostructures were proposed. The nickel ions first enter into the titanate matrix through three approaches, ion-exchanges reaction with the interlayered hydrogen ions, capillary forces from the microcavities, and electrostatic adsorptions due to the negatively charged outer surface of the titanate nanotubes. The following metallic nickel nucleation and growth may have occurred for these three kinds of the nickel ions reduced under hydrogen gas flow at elevated temperatures. The supports' titanate nanotubes may phase transform into the anatase titania nanocrystals and further into the mixture of anatase and rutile titania along with the increases of temperature. The Ni/titanate nanocomposites demonstrate paramagnetic behaviors and the Ni/titania nanocrystals display typical ferromagnetic behaviors. The Ni/titania sample reduced at 550 °C containing 14.5% rutile has higher photocatalytic activities than the sample reduced at 350 °C containing pure anatase, which is ascribed to a synergistic effect between anatase and rutile. The ferromagnetic characteristics of the Ni/titania products make them available as magnetically separable photocatalysts, which can be separated and recovered quickly by applying an external magnetic field.