We report the Eu doping induced improvement on the second harmonic generation (SHG) of ZnO nanowires and correlates with the structural modification and corresponding linear absorption. A non-monotonic enhancement in the SHG emission is observed with the increase of Eu concentration. To understand the underlying mechanism, the effective second order non–linear coefficient (deff) is calculated from the theoretical fitting with considering the absorption effect. The highest deff (19.09±0.11 pm/V) is obtained for the 1 at.% Eu doped ZnO nanowires, which is several times larger than the standard SHG material β-BaB2O4 (BBO). Dependence of the deff with the Eu doping, structural modification and absorption magnitude are systematically discussed.

In order to improve shape memory properties of Au-Cu-Al based shape memory alloys, the possibility to utilize thermo-mechanical treatment was investigated in this study, and effects of heat-treatment temperature on microstructure, martensitic transformation and mechanical properties of cold-rolled Au-30Cu-18Al-2Fe (AuCuAlFe) alloy were clarified by X-ray diffraction analysis (XRD, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and tensile tests at room temperature (RT). Here, Fe addition to AuCuAl improves ductility. Cold rolling with the thickness reduction of 30% was successfully carried out in AuCuAlFe at RT. An exothermic heat was observed in DSC at temperature from 402K, suggesting that recovery started at 402K. Besides, the transformation temperature hysteresis increased by the cold-rolling. The alloy was completely recrystallized after the heat treatment at 573K for 3.6ks. Tensile tests revealed that the yield stress was raised by cold rolling and largely by the subsequent heat treatment at 433K, which corresponded to the recovery start temperature by DSC. The yield stress decreased with increasing heat treatment temperature over 453K, probably due to recrystallization. AuCuAlFe cold-rolled and subsequent heat-treated at 573K exhibited the lowest yield stress as well as stress-plateau region, indicating that the thermo-mechanical treatment is effective to improve shape memory properties of Au-Cu-Al based alloys.

Seventy six speckled greenstone items have been recovered on the surrounding structures of the Aztec precinct of the Great Temple of Tenochtitlan. Several researchers have identified the material as marble. Also, these objects have been labeled as Mixtec style due to the raw materials involved in their manufacture as well as their apparent similarity with other known Mixtec objects. The main objective of this essay is to determine the raw materials and the technology employed on its manufacture. Based on earlier composition analysis using Infrared spectroscopy (FTIR) and X-ray Fluorescence (XRF), it became clear that all items are made of the same calcite-serpentine mineral alloy, which probably comes from the Oaxaca region. It is interesting the homogeneity and standardization among these pieces by analyzing them with experimental archaeology and the characterization of their manufacturing traces. Comparing their raw material, morphology and techniques with those of Mixtec sites, the analysis revealed that they are not in fact related at all; however they do coincide with the manufacturing process of Tenochca (Aztec) style objects. This fact might point towards the actual origin of the raw materials, their obtainment and the technology behind the elaboration of luxury goods at Tenochtitlan.

Surprisingly little is known about the mechanism and symmetry of superconducting pairing in PuCoGa5. A common thread with other unconventional superconductors is the presence of spin fluctuations in the normal state, which in this particular case is controlled by strong spin–orbit coupling split bands. The many and anisotropic Fermi surfaces make the guessing of the potential spin-fluctuation nesting vector and resulting symmetry of the pairing function a nontrivial task. To provide much needed guidance for the identification of the pairing symmetry in this multiband superconductor, we perform first-principles based magnetic spin susceptibility calculations to identify the dominant nesting vectors that potentially give rise to interband pairing with nodal d- or s±-wave gap functions.

The low resistance layer called p-type Surface Conductive Layer (PSCL) is formed when the nitrogen dioxide (NO2) was absorbed onto hydrogen-terminated surface, although the diamond is generally isolator. The PSCL conductance is dependent on NO2 concentration in the atmosphere, and this reaction has reversibility. The diamond having these characteristics can apply to gas sensor. In this study, the gas responsivity of PSCL was improved by surface treatment. The changes in the responsivity were evaluated from serial measurements of the conductance in the gas atmosphere. From this evaluation, it was observed that the adsorption and desorption of NO2 were faster via the surface conditions variation by treatment.

KNbO3 films were prepared at 100 - 240°C on (100)cSrRuO3//(100)SrTiO3 substrates by hydrothermal method using KOH and Nb2O5 as source materials. The incubation time before starting deposition and the deposition rate after starting deposition increased and decreased with decreasing deposition temperature, respectively. Epitaxial {100}c-oriented KNbO3 films with 300 nm thick were successfully obtained at 100°C on (100)cSrRuO3//(100)SrTiO3 substrates for 144 h. We observed the typical butterfly-shape strain curves originated from the piezoelectricity for the first time for KNbO3 films deposited down to 120°C.

In this paper we report the properties of the anodic silicon dioxide film formed using light-induced anodisation (LIA) method and its potential to be used as surface passivation layer of p-type silicon surfaces of silicon solar cells. The high uniformity of the formed oxide is possibly due to the uniform drift of the positive charge carriers in the silicon to the surface being anodised. The oxide grows at higher rate than that in nitric acid, an oxide layer with thickness of 18 nm can be formed by anodising for 10 min with 15 V bias in 0.5 M sulphuric acid. After annealing in oxygen and then forming gas at 400 °C for 30 min, an average effective carrier lifetime of 120 μs was measured by quasi-steady state photoluminance on 180 μm p-type 3-5 Ohm cm Cz silicon wafers, with a value of 110 μs being measured for the same wafers passivated by a thermally-grown oxide of the same thickness. The properties of the anodic silicon dioxide layers formed by LIA have been characterized by ellipsometry, x-ray photoelectron spectroscopy, quasi-steady state photoluminance and Fourier transform infrared spectroscopy.

Semi-crystalline structures were prepared from different processing condition. Biaxial oriented melt were crystallized at 375 K and atmospheric pressure for 10 nanoseconds (ns), to generate a lamellar semi-crystalline structure. Similar structures were also prepared from deformation of a cubic amorphous initial structure isothermally at 375 K. For comparison, two different thermostats, the constant stress (NPT) and constant volume (NVT) conditions were applied to the system during 10 ns of crystallization. The semi-crystalline samples shared common morphological features such as in the crystallinity, crystal orientation, lamellae thickness and density distribution, etc. However, during the subsequent uniaxial tensile deformation test of the samples to strain of 0.5, different stress-strain behaviors were demonstrated. By combining the observations of morphologies during deformation tests and analysis of the stress-strain curves, conclusions were made that the effectiveness of the network had a strong influence on the mechanical property and strain hardening behavior. The oriented network from the constant stress crystallization, owing to the taut chains, gave rise to optimal mechanical response with substantial strain-hardening.

In the current research, we have utilized sol-gel electrophoresis technique to grow PbTiO3 nanotube arrays in porous anodic alumina template channels. By using this method high quality and more condense nanotubes are obtained compared with other usual sol-gel methods. Also, the effect of the anodizing parameters on the diameter of the template pores, and effect of electrophoresis voltage on wall thickness were investigated.

The optical properties and electronic structure of AlPO4, SiO2, Type I collagen, and DNA were examined to gain insight into the van der Waals-London dispersion behavior of these materials. Interband optical properties of AlPO4 and SiO2 were derived from vacuum ultraviolet spectroscopy and spectroscopic ellipsometry, and showed a strong dependence on the crystals’ constituent tetrahedral units, with strong implications for the role of phosphate groups in biological materials. The UV-Vis decadic molar absorption of four DNA oligonucleotides was measured, and showed a strong dependence on composition and stacking sequence. A film of Type I collagen was studied using spectroscopic ellipsometry, and showed a characteristic shoulder in the fundamental absorption edge at 6.05 eV. Ab initio calculations based on density functional theory corroborated the experimental results and provided further insights into the electronic structures, interband transitions and vdW-Ld interaction potentials for these materials.

Aluminum doped ZnO (AZO) has been deposited on (100), (110) and (111) oriented n-type Si and on fused silica by atomic layer deposition (ALD). The films have been post deposition annealed in the temperature range 200-500 οC. The AZO films have been characterized by X-ray diffraction (XRD), Hall and transmittance measurements. Circular diodes have been fabricated from the AZO/Si structures and characterized by current-voltage (IV) and deep level transient spectroscopy (DLTS). The AZO films form Schottky junctions with the Si substrates for all the crystallographic orientations. It is established that after post deposition annealing the structure AZO/n-Si (110) is distinguished as the system with largest rectification.

Grain boundaries (GBs) in polycrystalline silicon (poly-Si) thin film solar cells are frequently found to be detrimental for device performance. Biaxiallytextured silicon with grains that are well-aligned in-plane and out-of-plane can possess fewer GB defects. In this work, we use TCAD Sentaurus device simulator and known experimental work to investigate and quantify the potential performance gains of biaxially-textured silicon. Simulation shows there can be performance gain from well-aligned grains when GB defects dominate carrier recombination or when grains are small. On the other hand, when intra-grain defects dominate recombination and grains are large, well-aligned grains do not lead to much performance gain. Another important result from our simulation is when intra-grain and GB defects are few, Jsc is almost independent of grain size while Voc drops with decreasing grain size.

The key material behavior of graphene, a single layer of carbon lattice, is extremely sensitive to its dielectric environment. We demonstrate improvement in electronic performance of graphene nanowire interconnects with full encapsulation by lattice-matching, chemically inert, 2D layered insulator hexagonal boron nitride (h-BN). A novel layer-based transfer technique is developed to construct the h-BN/MLG/h-BN heterostructures. The encapsulated graphene wires are characterized and compared with that on SiO2 or h-BN substrate without top passivating h-BN layer. Significant improvements in maximum current-carrying density, breakdown threshold, and maximum power density in encapsulated graphene wires are observed. These critical improvements are achieved without compromising the carrier transport characteristics in graphene. Furthermore, graphene wires exhibit electrical behavior much less insensitive to ambient conditions, as compared with the non-passivated ones. Overall, h-BN/graphene/h-BN heterostructure presents a robust material platform towards the implementation of high-performance carbon-based interconnects.

The topic of Urban Solid Waste (USW) has become increasingly controversial in our times due to the high volumes being produced and not disposed properly; one effective way to reduce the generation of USW is finding new ways to recycling. This study proposes a means of recycling Tetra Brik® (TBr) cartons and high density polyethylene recycled containers (HDPEr), by generating an agglomerate with optimal mechanical properties in comparison with other TBr-based agglomerates. For the analysis of this material’s mechanical properties, two types of evaluation tests are carried out; flexure and screw pull-out test. Results show significant mechanical advantages over other TBr-based laminates by the integration of an HDPEr matrix to the system, thereby improving mechanical properties.

The iridescent colors of Morpho butterflies have captured scientific intrigue for over a century. However, only recently photonic structures of the wing scales of Morpho butterflies have inspired new ideas in the diverse areas of technology including sensing. In this study, we performed theoretical and experimental evaluation of vapor-induced reflectance changes of the Morpho scales. These experiments provided additional details of the origin and the magnitude of vapor response selectivity in these natural photonic nanostructures and facilitated our design and fabrication of highly selective biomimetic photonic nanostructures.

We report simulation of optical properties of hybrid geometry comprised of multilayer graphene shell encapsulated gold nanoparticles loaded with carbon nanotubes. The discrete dipole approximation (DDA) method was employed. The results indicated that the optical properties of encapsulated gold nanoparticles were not suppressed by the carbon material coating. Furthermore, low scattering effects were also observed. The simulation method helped visualize the near-surface normalized electric field, which is directly related to the intensity of hot spots on the surface of these hybrid nanoarchitectures.

Magnetic/fluorescent (magnetofluorescent) materials have become one of the most important tools in the imaging modality in vivo using magnetic resonance imaging (MRI) and fluorescence imaging. We succeeded in fabricating magnetofluorescent nanoparticles (MFNPs) consisting of silicon/magnetite composite nanoparticles. Our unique synthetic approach can control simultaneously the magnetic and fluorescence behaviors by varying the particle size, demonstrating the superparamagnetic behavior and green fluorescence for the MFNPs having mean diameter of 3.0 nm, and the ferromagnetic behavior without fluorescence for the MFNPs having mean diameter more than 5.0 nm. More intriguingly, the MFNPs with superparamagnetism can detect green fluorescence even after the magnetic guidance of MFNPs by the commercial neodymium magnet. Additionally, the MFNPs having two magnetic behaviors also possess good biocompatibility.

Taking the advantage of nanomaterials to protect the environment and avoiding the side effect need a fundamental understanding of the growth mechanism of the nanomaterials. Here, the van der Waals interaction between a nanoparticle and a nanotube in the oriented-attachment growth of nanotubes is quantitatively evaluated for the first time. In particular, the correlation between van der Waals interaction and the growth parameters is investigated in depth. Our work opens up the opportunity of studying the important interparticle interactions in the oriented attachment growth of nanotubes.

The accumulation of boron within the porous nickel ferrite (NiFe2O4, NFO) deposits on nuclear fuel rods is a major technological problem with important safety and economical implications. In this work, first-principles results are combined with experimental thermochemical data to analyze the energetics of vacancy formation in NFO and the possibility of B incorporation into the structure of NFO. Under solid-solid equilibrium conditions, the calculations suggest that vacancy formation and B incorporation into the NFO structure is energetically unfavorable, the main limiting factors being the narrow stability domain of NFO and the precipitation of B2O3, Fe3BO5, and Ni3B2O6 as secondary phases. Assuming solid-liquid equilibrium between NFO and the surrounding aqueous solution saturated with respect to NFO, the calculations predict that in operating PWR environment, Ni vacancies are likely to form. Under these conditions the possibility of B incorporation at the Ni vacancy sites cannot be excluded.