Intrinsic Terahertz Plasmons and Magnetoplasmons in Large Scale Monolayer Graphene

We show that in graphene epitaxially grown on SiC the Drude absorption is transformed into a strong terahertz plasmonic peak due to natural nanoscale inhomogeneities, such as substrate terraces and wrinkles. The excitation of the plasmon modifies dramatically the magneto-optical response and in particular the Faraday rotation. This makes graphene a unique playground for plasmon-controlled magneto-optical phenomena thanks to a cyclotron mass 2 orders of magnitude smaller than in conventional plasmonic materials such as noble metals.Comment: to appear in Nano Letter

Avoiding Loss of Catalytic Activity of Pd Nanoparticles Partially Embedded in Nanoditches in SiC Nanowires

Nanoditches from selective etching of periodically twinned SiC nanowires were employed to hinder the migration and coalescence of Pd nanoparticles supported on the nanowires, and thus to improve their catalytic stability for total combustion of methane. The results show that the etched Pd/SiC catalyst can keep the methane conversion of almost 100% while the unetched one has an obvious decline in the catalytic activity from 100 to 82% after ten repeated reaction cycles. The excellent catalytic stability originates from the limitation of the nanoditches to the migration and growth of Pd nanoparticles

Effect of Defects on Graphitization of SiC

Epitaxial graphene and carbon nanotubes (CNTs) grown on SiC have shown big potential in electronics. The motivation to produce faster and smaller electronic devices using less power opened the way to a study of how to produce controlled epitaxial graphene and CNTs on SiC. Since defects are among the important tools to control the properties of materials, the effects of defects on the carbon formation on SiC have been analyzed. In this study, the effects of defects on the carbon formation on SiC have been analyzed. We produced carbon films on the surface of four different SiC materials (polycrystalline sintered SiC disks, single crystalline SiC wafers, SiC whiskers, and nanowhiskers) by chlorination and vacuum annealing with the goal to understand the effects of surface defects on the carbon structure and the SiC decomposition rate. We have shown that grain boundaries, dislocations, scratches, surface steps, and external surfaces may greatly enhance the reaction rate and affect the final structure of carbon derived from SiC

Noncatalytic Synthesis of Carbon Nanotubes, Graphene and Graphite on SiC

Graphene and carbon nanotubes (CNT) can be produced by vacuum decomposition of SiC, but discrepancies and conflicting data in the literature limit the use of this method for CNT synthesis. A systematic study of the effects of SiC surface morphology and carbon transport through the gas phase leads to reproducible and controlled growth of arrays of small-diameter (1-4 walls) nanotubes, which show pronounced radial breathing modes in Raman spectra, on either carbon (0 0 0 over(1, -)) or silicon (0 0 0 1) face of 6H SiC wafers at 1400-1900 °C. These nanotube arrays have a very high density and are catalyst-free with no internal closures. They show a higher oxidation resistance compared to CNTs produced by catalytic chemical vapor deposition (CVD). Their integration with graphite/graphene or silica layers on SiC wafers is possible in a simple 2-step process and opens new horizons in nanoscale device fabrication

Characteristic Properties of Dy-Eu-Ce Co-Doped ZrO2 Nanofibers Fabricated via Electrospinning

2nd International Conference on Computational and Experimental Science and Engineering (ICCESEN) -- OCT 14-19, 2015 -- Kemer, TURKEYWOS: 000384810700079Zirconium oxide (ZrO2) is one of the widely studied oxide materials because of its excellent electrical, mechanical and optical properties. In this study, undoped and Dy-Eu-Ce co-doped ZrO2 nanofibers were fabricated by electrospinning method and their crystal structure, surface morphology, optical properties, electrical and electronic properties, and chemical properties have been analyzed using X-ray diffraction, scanning electron microscope (SEM), UV/VIS spectrometer, four point probe technique ( FPPT) energy dispersive X-ray (EDX) measurements, respectively

New constraints on micro-seismicity and stress state in the western part of the North Anatolian Fault Zone: Observations from a dense seismic array

With the aim of extensively investigating the crustal structure beneath the western segment of the North Anatolian Fault Zone where it splays into northern and southern branches, a temporary seismic network (dense array for North Anatolia-DANA) consisting of 70 stations was deployed in early May 2012 and operated for 18 months in the Sakarya region during the FaultLab experiment. Out of 2437 events contaminated by explosions, we extracted 1371 well located earthquakes. The enhanced station coverage having a nominal station spacing of 7 km, lead to a minimum magnitude calculation of 0.1. Horizontal and vertical location uncertainties within the array do not exceed 0.8 km and 0.9 km, respectively. We observe considerable seismic activity along both branches of the fault where the depth of the seismogenic zone was mostly confined to 15 km. Using our current earthquake catalog we obtained a b-value of 1. We also mapped the b-value variation with depth and observed a gradual decrease. Furthermore, we determined the source parameters of 41 earthquakes with magnitudes greater than 1.8 using P-wave first motion polarity method. Regional Moment Tensor Inversion method was also applied to earthquakes with magnitudes greater than 3.0. Focal mechanism solutions confirm that Sakarya and its vicinity is stressed by a compressional regime showing a primarily oblique–slip motion character. Stress tensor analysis indicates that the maximum principal stress is aligned in WNW–ESE direction and the tensional axis is aligned in NNE–SSW direction