The food processing industry highlights the daily generation of large amounts of eggshell solid residue. In this way, this residue becomes a non renewable raw material to be reused as an additive in red ceramics, in order to reduce the volume of disposal to the environment and improve the physical properties of the product. The objective of this work was to evaluate the forming moisture, linear shrinkage of drying and shrinkage of drying burning of ceramic test pieces (CS’s) with formulations with 2% and 3% of white eggshell residue (ER) incorporated in clay. The clay and ER were collected in the city of Pelotas-RS. The ER sample was analyzed by X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD). After pressing, natural and artificial drying was carried out and the CS’s were burned. These were evaluated through normative parameters C-020/95, C-021/95 and C-026/95. The values obtained for the forming moisture were between 5.82 and 8.78%, for the linear shrinkage of drying between 0.10 and 0.43% and, for the linear contraction burning between -0.29 and 0.08%. The results showed that the addition of ER to the ceramic mass helped in the reduction of the forming moisture and the linear shrinkage of the ceramic test pieces.

To improve conversion efficiency of silicon nanowire (SiNW) solar cells, it is very important to reduce the surface recombination rate on the surface of SiNWs, since SiNWs have a large surface area. We tried to cover SiNWs with aluminum oxide (Al2O3) and titanium oxide (TiO2) by atomic layer deposition (ALD), since Al2O3 grown by ALD provides an excellent level of surface passivation on silicon wafers and TiO2 has a higher refractive index than Al2O3, leading to the reduction of surface reflectance. The effective minority carrier lifetime in SiNW arrays embedded in a TiO2/Al2O3 stack layer of 94 μsec was obtained, which was comparable to an Al2O3 single layer. The surface reflectance of SiNW solar cells was drastically decreased below around 5% in all of the wavelength range using the Al2O3/TiO2/Al2O3 stack layer. Heterojunction SiNW solar cells with the structure of ITO/p-type hydrogenated amorphous silicon (a-Si:H)/n-type SiNWs embedded in Al2O3 and TiO2 stack layer for passivation/n-type a-Si:H/back electrode was fabricated, and a typical rectifying property and open-circuit voltage of 356 mV were successfully obtained.

Copper growth for the development of electroplating technique as a low-temperature soldering procedure represents a useful method for the formation of metal deposits, allowing modification of the thickness and morphology of the soldering joints. The approach is particularly useful for soldering electronic components to a plastic 3D printed substrate. To accelerate the soldering process hydrogen assisted electroplating (HAE) method was employed at room temperature. The experiments were designed by making a small electrochemical cell around the gap on a printed circuit board (PCB) or a 3D printed conductive track. During the experiment, water electrolysis was observed, which released hydrogen bubbles. The hydrogen bubbles caused the structure of the electroplated layer to be more porous, but with a similar conductivity as solid copper and a remarkable mechanical strength suitable for use as interconnects on an electronic circuit. Our electrochemical data and video recorded images show a fast and reliable copper electrodeposition in less than 1 minute. The morphology of copper deposits on a 3D printed structure was studied with the scanning electron microscopy (SEM). A reliable soldering process was demonstrated for a surface mount light emitting diode (LED) on a PCB. Further experiments are required to optimize the soldering process for faster and more reliable electroplating, particularly for 3D printed substrates.

The aim of this research was to investigate the influence of substrate roughness on the adhesion and tribological performance of thin TiN coatings obtained by physical vapor deposition. For that purpose, substrates of AISI H13 steel with surface finishes of 0.06, 0.28 and 0.90 μm in Ra were coated with TiN under the same coating conditions. The chemical composition of the steel, as well as that of the TiN coating, were obtained using EDS analysis. Adhesion tests were carried out following the procedure of BSi 1071-8 standard while hardness was evaluated by ASTM C 1327-03. On the other hand, dry sliding friction tests were conducted with a pin-on-disk tribometer, according to the ASTM G 99-05 standard. This study showed that the roughness of the coating increases as the substrate roughness increases. Regarding adhesion and hardness, all the samples showed an adhesion class 1 according to the standard and a hardness value of 14.51 GPa. Nevertheless, the highest substrate roughness produced the best adhesion. On the other hand, the lowest values for the friction coefficient and wear behavior were obtained by the sample with the lowest substrate roughness of 0.06 µm. In addition, it was found that friction and wear increase when the substrate roughness increases.

Over the last decade, polymer composites reinforced with natural fibers gained interest, both from the academic world and from various industries. Due to the demanding needs for environmentally friendly composites, the automotive industry is now searching for biodegradable and renewable composite materials and products. There are a wide variety of different natural fibers which can be applied as reinforcement or fillers, showing potential as a replacement for inorganic fibers in automotive components. The fact that plastics are often economical to produce implies an advantage especially in very complex shapes, make them promising for obtaining composite materials, achieving short demolding times, as no chemical reaction is required. Moreover, polymers are used increasingly for stressed tribological components, whereby plastic parts replace metallic bearings, gear wheels or sliding elements. In this regard, the objective of this work was to produce composite materials based on natural fibers and to characterize the influence of the addition of different amounts of filler. To do so, composites of high-density polyethylene (HDPE) and peanut shells (PS), at different proportions (2, 4 6, 8 and 10% wt.), were prepared. The composites were produced by injection molding and molded into a particular tension test simple mold. Although the FTIR presented an increment on the O-H vibration and a band around 1600 cm-1, the HDPE structure did not present modification. The mechanical properties of the HDPE were affected with the inclusion of the fibers. The tensile performance of the HDPE decrease with the increment of the fibers inclusion whiles the elastic modulus increases. The sample with 2% of natural fibers presented the lowest wear rate (k) and coefficient of friction (µ).

A combination of dimensional analysis and finite element modeling was invoked to characterize the indentation behavior of transversely isotropic thin films on substrate materials. Through indentation simulations of over 13,500 combinations of properties for the thin film system, functional relationships that connect the indentation responses of the thin films with the elastic and plastic properties of the thin films were obtained. The forward algorithms that predict the indentation response characteristics from known material properties and the reverse algorithms that predict the material properties from known indentation responses were verified to be very accurate. Thus, the viability of using the indentation method to determine the elastic and plastic properties of transversely isotropic thin films on substrate materials was demonstrated.

Immobilization of bulk liquid high level radioactive waste (HLW) in Synroc ceramic is well-known reliable way for final isolation of dangerous long-lived radionuclides from biosphere. The alternative method of Synroc-like ceramic synthesis has been proposed. Radionuclide incorporation into crystalline titanate host-phases can be provided as a result of direct radionuclide sorption from liquid HLW using non-selective sorbent – layered hydrazinium titanate (LHT-9). Such an approach allows excluding expensive multi-stage procedure of precursor preparation. The precipitate obtained after sorption can be easily transformed into Synroc-like ceramic by cold pressing followed with sintering in air at 1000-1200°C. The highly radioactive samples of titanate ceramic loaded with real HLW have been synthesized and preliminary studied at KRI hot-cell facility. Chemical durability of this sample has been studied using static leach test in distilled water at 90°C and the leach rates for 154Eu, 241Am, 244Cm were (in g·m-2·day-1) from 2·10-4 to 5·10-3. Normalised 137Cs mass loss was 0.3 g·m-2 for 110 days at the same conditions.

The exotic characteristics of nanoscopic metallic materials bestows diverse functionalities that are increasingly being utilized for a broad range of applications. Polymer substrates present robust architectures for nanoparticle anchoring as well as modulating attendant size-induced aggregation. However, in principle, interfacial adhesion of a polymer-metal material system is weak, making the susceptibility to delamination a challenge. We have deposited copper particles on model polymer thin film and fibrous architectures to study adhesion behavior on these distinct geometries. The average sizes of copper nanoparticles deposited on electrospun fibers for metallization times of 3 and 5 minutes were 13 and 10 nm, whereas the metal island sizes under same metallization times on thin films was 79nm and 81nm. Scratch tests using a nanoindentation system were unable to generate macroscopic film delamination, but did exhibit apparent removal of individual particles, with adhesion forces of 14.9μN, 36μN, and 28.8μN obtained for films metallized for 1, 3, and 5 minutes respectively. Macroscopic tensile testing of fiber mats showed the metallization maintains conformity with the polymer ligament, albeit, with intermittent fracture of the conformal metal coating, signifying substantial adhesion exists between the metallic layer and the PAN fiber.

This study reports a high-performance tin (Sn)-coated vertically aligned carbon nanofiber array anode for lithium-ion batteries. The array electrodes have been prepared by coaxial sputter-coating of tin (Sn) shells on vertically aligned carbon nanofiber (VACNF) cores. The robust brush-like highly conductive VACNFs effectively connect high-capacity Sn shells for lithium-ion storage. A high specific capacity of 815 mAh g-1 of Sn was obtained at C/20 rate, reaching toward the maximum value of Sn. However, the electrode shows poor cycling performance with conventional LiPF6 based organic electrolyte. The addition of fluoroethylene carbonate (FEC) improve the performance significantly and the Sn-coated VACNFs anode shows stable cycling performance. The Sn-coated VACNF array anodes exhibit outstanding capacity retention in the half-cell tests with electrolyte containing 10 wt.% FEC and could deliver a reversible capacity of 480 mAh g-1 after 50 cycles at C/3 rate.

Recently the use of nanomaterials for the diagnosis and detection of malignant diseases has increased due to the versatility and properties of these nanostructures. For this work 60 nm commercial gold nanoparticles (TED PELLA inc.) and Nanostars manufactured by chemical synthesis (precursor reagent: HAuCl4, cationic surfactant: CTAB) of 117 nm were used for coating. Malachite green Isotyocianate (MGITC), mPEG-SH and ortho-pyridyldisulfide-polyethylene glycol-N-succinimidyl propionate (OPSS-PEG-NHS) was used. A SERS active nanoparticle complex was obtained by addition of a solution of MGITC to the gold nanoparticles colloidal solution in a 1:6 ratio. Later, an mPEG-SH solution was added to the mix. The nanoparticle-MGITC-mPEG-SH complex stability was revised using a UV-Vis spectrophotometer and a JEOL JEM 1000 transmission electron microscope. The SERS spectra were registered with a Raman Thermoscientific DXR microscopy system. Amplified bands associated with OPSS-PEG-NHS were identified in 389, 622, 859, 929, 1080, 1283, 1360, 1443, 1490 and 1450 cm-1. The results indicate that through this methodology it is possible to identify gold nanomaterials coated with polymer through the Raman technique. In addition, greater amplification is observed with the use of nanostars compared to gold spheres. Finally, these nanomaterials are available for the marking of specific membrane for the study of different types of cancer by the SERS technique.

Much of the global agricultural by products go waste, especially in developing nations where much of their revenues depend on the exports of raw agricultural products. Such waste streams, if converted to “value added” products could serve as additional source of revenue while simultaneously having a positive impact on the socio-economic well being of the people. We present a preliminary investigation on utilizing chemical activation technique and ball milling to convert agricultural waste streams such as cocoa pod, coconut husk, palm midrib and calabash commonly found in Ghana into ultra-high surface area activated carbon. Such activated carbons are suitable for myriads of applications in environmental remediation, climate management, energy storage and conversion systems (batteries and supercapacitors), and improving crop productivity. We achieved BET surface area as high as ∼ 3000 m2/g.

Recent strategy in the electronics sector is to ascertain the ways to make cheap, flexible and environmentally friendly electronic devices. The 3D inkjet printing technology is based on the Additive Manufacturing concept and it is with no doubt capable of revolutionising the whole system of manufacturing electronic devices including: material selection; design and fabrication steps and device configuration and architecture. Thus, 3D inkjet printing technology (IJP) is not only one of the most promising technologies to reduce the harmful radiation/ heat generation but also achieve reductions in manufacturing cost. Here, we explore the potential of 3D – inkjet printing technology to provide an innovative approach for electronic devices in especially information storage elements by seeking to manufacture and characterise state-of-art fully inkjet printed two terminal electronic memory devices. In this work, ink-jettable materials (Ag and PEDOT:PSS) were printed by a piezoelectric Epson Stylus P50 inkjet printing machine on a flexible substrate. All components of the memory cells of a simple metal/active layer/metal structure were deposited via inkjet printing. The quality of the printed layers was first assessed by Nikon LABOPHOT-2 optical microscope, fitted with Nikon Camera DS-Fi1. Furthermore, an in-depth electrical characterisation of the fabricated memory cells was carried out using HP4140B picoammeter.

The effect of tunnel cations on tunnel size in α-MnO2 structured (hollandite, cryptomelane) materials has long been of interest, as the tunnel size effects catalytic and transport properties. Previous research on the tunnel size has focused on potassium cryptomelane (KxMn8O16). This paper uses synthetic control of silver content in AgxMn8O16 to investigate the effect that tunnel silver occupancy has on the lattice parameters. Materials with silver (x) content between 1.14 and 1.66 were synthesized, synchrotron diffraction and Rietveld Refinement was used to determine lattice parameters. The lattice parameters were found to contract as silver content increases (from 9.774 Å to 9.738 Å), in contrast to previous investigations of other tunnel cations.

Optical antennas made out of materials with hyperbolic dispersion is an alternative approach to realizing efficient subwavelength scatterers and may overcome limitations imposed by plasmonic and all-dielectric designs. Recently emerged natural hyperbolic material hexagonal boron nitride supports phonon-polariton excitations with low optical losses and high anisotropy. Here we study scattering properties of the hyperbolic-medium (HM) antennas, and in particular, we consider a combination of two types of the particles - HM bars and silicon spheres - arranged in a periodic array. We analyze excitation of electric and magnetic resonances in the particles and effect of their overlap in the array. We theoretically demonstrate that decrease of reflectance from the array can be achieved with appropriate particle dimensions where electric and magnetic resonances of different particle types overlap, and the resonance oscillations are in phase. In this case, generalized Kerker condition is satisfied, and particle dimers in the array efficiently scatter light in the forward direction. The effect can be used in designing metasurfaces based on hexagonal boron nitride scatterers with an application in mid-infrared photonics.

Here we report the use of luminescence thermometry to measure the temperature decay from single gold structure into the substrate of AlGaN:Er3+ film. We looked at Er3+ ion photoluminescence upon illumination by modulated 532 nm laser and recorded time-resolved luminescence of 2H11/2 → 4I15/2 and the 4S3/2 → 4I15/2 energy transitions. We calculated the heat generated from gold microdisk and observed the rate of heat dissipation to the environment. We directly calculated the absolute thermal conductivity of 1.7 W/mK for AlGaN: Er3+ film which was in agreement with the literature.

(Ga55In45)2S300 and (Ga54.59In44.66Er0.75)2S300 single crystals were successfully grown with the aim of exploring their potential for laser induced third harmonic generation (THG) and piezo-optical applications. Their Raman and luminescence spectra in the 150-300 K temperature range were studied. Influence of different gamma ray doses on the nonlinear optical properties were also explored. The optical properties of these crystals exhibit strong variation with temperature. It is concluded that (Ga54.59In44.66Er0.75)2S300 may be applied as promising materials for dosimetry applications in γ - radiation and optical temperature sensors.

In most materials, surfaces and interfaces present a significant portion of the workable area, but this area has often been erroneously perceived as a challenge in processing and thus, largely ignored. Surfaces and interfaces, however, present a network of energetically mismatched (sometimes metastable) molecules that can be exploited to either control surface reactions, engineer bulk stability or reveal new fundamental details of otherwise not well understood processes or systems as described herein. This perspective captures the role of i) structure, ii) chemistry and iii) thermodynamics at the interface in fabricating functional materials. Engineering substrate morphology enables tunable wettability either through the substrate or an adsorbed self-assembled monolayer (SAM), the latter being largely due to effect of sub-nanoscale roughness on conformational defects and overall order in the SAM. Surface roughness and chemistry also dictates the nature and amount of adventitious contaminants on a surface, and this was used to control volume of adsorbed water leading to controlled and tunable step-growth polymerization. The chemical treatment renders the paper amphiphobic, which could be used for self-cleaning surfaces and nucleation of water microdroplets for water harvesting. Finally, creating a self-passivating polished thin (∼0.7-2 nm) shell on a molten metal microdroplet kinetically frustrates solidification leading to significant undercooling. The ambient undercooled liquid metal is used for mechanically-triggered heat-free solder and smart composites. These three cases demonstrate key aspects of surface and interface engineering in integrating well-known concepts for the development of functional materials.