We study effects of deposition temperature on growth mode and surface morphologyof hetero-epitaxial (ZnO)x(InN)1-x (ZION) films on ZnOtemplates. ZION films deposited at low temperature of RT-250oC growtwo dimensionally, whereas ZION films deposited at high temperature of350-450oC grow three dimensionally. Growth mode is changed fromtwo-dimensional growth mode to three-dimensional one, because the criticalthickness where film strain begin to relax decreases with increasing thedeposition temperature. At high deposition temperatures, the number of pointdefects in ZION films decreases because migration of adatoms on the growingsurface is enhanced. The strain energy in ZION films increases with increasingthe deposition temperature, since the strain energy is not released by pointdefects. Therefore, lattice relaxation for the higher deposition temperaturebegins at the smaller film thickness to release the strain energy. As a result,ZION films with atomically-flat surface were obtained even at RT.

Covalent functionalisation of collagen has been shown to be a promising strategyto adjust the mechanical properties of highly swollen collagen hydrogels. At thesame time, secondary interactions between for example, amino acidic terminationsor introduced functional groups also play an important role and are oftenchallenging to predict and control. To explore this challenge, 4-vinylbenzylchloride (4VBC) and methacrylic anhydride (MA) were reacted with type Icollagen, and the swelling and rheological properties of resultingphoto-activated hydrogel systems investigated. 4VBC-based hydrogels showedsignificantly increased swelling ratio, in light of the lower degree of collagenfunctionalisation, with respect to methacrylated collagen networks, whilstrheological storage moduli were found to be comparable between the two systems.To explore the role of benzyl groups in the mechanical properties of the4VBC-based collagen system, model chemical force microscopy (CFM) was carriedout in aqueous environment with an aromatised probe against an aromatisedgold-coated glass slide. A marked increase in adhesion force(F: 0.11±0.01 nN) was measured between aromatisedsamples, compared to the adhesion force observed between the non-modified probeand a glass substrate (F: 2.64±1.82 nN). These resultssuggest the formation of additional and reversible π-πstacking interactions in aromatic 4VBC-based networks and explain the remarkablerheological properties of this system in comparison to MA-based hydrogels.

Percolation of blood and of interstitial fluids into implantable continuous glucose sensors (CGS) for diabetics presently limits sensor lifetime between 3 and 7 days. Na+ mobile ions in body fluids damage Si-based CGS sensors electronics. The direct detection of Na percolation is investigated by Ion Beam Analysis (IBA) and Proton Induced X-ray Emission (PIXE) in previously used CGS. Based on these results, a new technology called HemaDropTM is then tested to prepare small volume (5-10 µL) of blood for IBA. A species’s detectability by IBA scales with the square of the ratio of element’s atomic number Z to that of the substrate. Because Na has a low atomic number (Z=11), Si signals from sensor substrates can prevent Na detection in Si by 2 mega electron volt (MeV) IBA.

Using 4.7 MeV 23Na (α, α)23Na nuclear resonance (NR) can increase the 23Na scattering cross section and thus its detectability in Si. The NR energy, width, and resonance factor, is calibrated via two well-known alpha (α) particle signals with narrow energy spreads: a 5.486 ± 0.007 MeV 241Am α-source (ΔΕ = 0.12%) and the 3.038 ± 0.003 MeV 16O(α, α)16O NR (ΔΕ = 0.1%). Next, the NR cross section is calibrated via 100 nm NaF thin films on Si(100) by scanning the beam energy. The23Na (α, α) NR energy is found to be 4.696 ± 0.180 MeV, and the NR/RBS cross section 141 ± 7%. This is statistically significant but small compared to the 4.265 MeV 12C NR (1700%) and 3.038 MeV 16O NR (210%), and insufficient to detect small amounts of 23Na in Si. Next, a new method of sample preparation HemaDropTM, is tested for detection of elements in blood, such Fe, Ca, Na, Cl, S, K, C, N, and O, as an alternative to track fluid percolation and Na diffusion in damaged sensors. Detecting more abundant, heavier elements in blood and interstitial fluids can better track fluid percolation and Na+ ions in sensors. Both Na detection and accuracy of measured blood composition by IBA is greatly improved by using HemaDropTM sample preparation to create Homogeneous Thin Solid Films (HTSFs) of blood from 5-10 µL on most substrates. HTSF can be used in vacuo such as 10-8 –10-6 Torr).

Cr, V, and Fe amino borohydride complexes were synthesized using a solution based approach. Thermogravimetric Analysis with simultaneous Differential Scanning Calorimetry was used to investigate their decomposition behavior. The synthesized Cr and Fe complexes exhibited significant hydrogen release around 100 °C. The synthesized V complex showed a large mass loss at temperatures between 50 °C and 100 °C and release of amine byproducts. FTIR of decomposed intermediates showed the decomposition of Cr amino borohydride occurs through the simultaneous loss of hydrogen from both the borohydride and amino ligands, while the Fe complex displays preferential dehydrogenation of the borohydride over the amino ligand. The decomposed products take on a BN type structure when heated to 400 °C.

Removing residual moisture in lithium-ion battery electrodes is essential for desired electrochemical performance. In this manuscript, the residual moisture in LiNi0.5Mn0.3Co0.2O2 cathodes produced by conventional solvent-based and aqueous processing is characterized and compared. The electrochemical performance has also been investigated for various residual moisture contents. It has been demonstrated that the residual moisture lowers the first cycle coulombic efficiency, but its effect on short term cycle life is insignificant.

This study focuses on understanding the influence of incorporating Ammonium Acetate into the chemical bath used for the deposition of CdS thin films, on its optical, morphology, and microstructural properties. Thus, CdS thin films were deposited on 1” × 2” microscopic glass substrates using chemical bath deposition (CBD) technique. The deposition process was carried out in a double jacket beaker with fixed chemical bath temperature of 90°C for a deposition time of 40 min. The chemical bath solution consisted of fixed concentrations of Cadmium Acetate, Thiourea, and Ammonium Hydroxide; with corresponding values of 4.8×10-4M; 0.97×10-4M; and 0.2M, respectively. However, Ammonium Acetate was incorporated into the deposition bath with concentrations that were varied from 3.0 mM to 12.2 mM. Meanwhile, for comparison purposes associated to the initial physical and chemical properties of the CdS films; reference CdS films were deposited under the same above chemical bath conditions, but in the absence of Ammonium Acetate. The pH of the chemical bath was measured during the deposition process. The films’ morphology and the chemical composition were examined by Field Emission Scanning Electron Microscopy (FE-SEM), and the Energy Dispersive spectrometer (EDS), respectively. The X-Ray Diffraction (XRD) θ/2θ technique was applied to study the structure of the films, including the lattice parameters. Atomic Force Microscopy (AFM) was used to examine the films topography and to determine the root-mean-square (RMS) surface roughness of the films as well as the grain size. Dektak Surface Profilometer was used to determine the CdS films’ thickness, where the films’ optical properties were measured using UV-Vis-NIR spectrometer. Optical energy band gap (Eg), and absorption coefficient (α) were calculated from the transmission spectral data.

With the recent terrorist attacks in Paris and the continued use of IED’s employing TATP for delivering these threats, there is a real need for explosives detection at trace levels. This work describes the fabrication and characterization of metal oxide nanowires used as catalysts for the detection of energetic materials at trace levels. Recently, several oxide nanowires, based on zinc oxide and copper oxide, have been incorporated into our solid-state gas sensors as catalysts. These nanowire catalysts produced a dramatic increase in sensor response with improved selectivity for threat molecules of interest. The improved responses were attributed to a large increase in surface area available for catalyst/analyte interaction. Zinc oxide and copper oxide nanowires were grown by hydrothermal and controlled oxidation reactions, and were characterized using XRD, XPS and SEM to determine extent of crystallinity, oxidation state and morphology. Results indicated that energetic materials such as TATP and 2-6 DNT could be detected at the part per billion level using these nanowire catalysts. Other oxide nanowires are being considered as catalysts for the detection of explosives and are discussed as well.

A severe plastic deformation (SPD) technique was applied to an Al-7075 alloy reinforced with 10 vol.% Al2O3. This processing method of high-pressure torsion (HPT) was performed at room temperature under a pressure of 6.0 GPa through a total number of up to 20 turns. The metal matrix composite (MMC) showed a significant grain refinement from an initial average grain size of ∼8 μm to ∼300 nm after processing by HPT through 20 turns which led to an increase in the average values of Vickers microhardness at room temperature.

A new high rate deposition method has been used to fabricate thin film CdTe photovoltaic devices using pulsed dc magnetron sputtering. The devices have been deposited in superstrate configuration on to a commercial fluorine doped tin oxide transparent conductor on soda lime glass. The cadmium sulphide and cadmium telluride thin films were deposited from compound targets. The magnetrons were mounted vertically around a cylindrical chamber and the substrate carrier rotates so that the layers can be deposited sequentially. The substrates were held at 200°C during deposition, a process condition previously found to minimize the stress in the coatings. Optimization of the process involved a number of parameters including control of pulse frequency, power and working gas pressure. The devices deposited using the process are exceptionally uniform enabling the CdTe absorber thickness to be reduced to ∼1um. The as-deposited material is dense and columnar. The cadmium chloride treatment increases the grain size and removes planar defects. The microstructure of the films before and after activation has been characterized using a number of techniques including transmission electron microscopy, Energy Dispersive mapping and these measurements have been correlated to device performance. The deposition rate is much higher than can be obtained with radio-frequency sputtering and is comparable with methods currently used in thin film CdTe module manufacturing such as Vapour Transport Deposition and Close Space Sublimation.

Zinc oxide has recently been touted as a material that may prove useful for high-power and high-frequency electron device applications. Unfortunately, at the present moment at least, zinc oxide’s electron transport results are based upon material parameter selections that remain disputed, i.e., their exact values have yet to be satisfactorily resolved. In order to establish how the expected range of disputed material parameter values influence the corresponding electron transport results, this paper assesses the sensitivity of the electron transport results associated with zinc oxide to variations in these disputed material parameters. The disputed material parameters that we focus on for the purposes of this particular analysis include the non-parabolicity coefficient associated with the lowest energy conduction band valley, the conduction band inter-valley energy separation, and the effective mass associated with the electrons in the upper energy conduction band valleys. For the purposes of this analysis, steady-state electron transport results are the focus of this sensitivity analysis, the velocity-field characteristic associated with zinc oxide being the principal metric of concern. We find that increases in the non-parabolicity coefficient associated with the lowest energy conduction band valley lead to increases in the peak field of the velocity-field characteristic and initially an increase and then a decrease in the peak electron drift velocity of this material. Increases in the conduction band inter-valley energy separation are instead found to result in increases in the peak field and concomitant increases in the peak electron drift velocity. Finally, increases in the effective mass associated with the electrons in the upper energy conduction band valleys are found to lead to a sharpening of the slope of the velocity-field characteristic in the region beyond the peak field, greater effective mass leading to a greater magnitude slope. Based on the magnitude of these variations, we conclude that zinc oxide may indeed be considered as a material for high-power and high-frequency electron device applications even when the variations in these disputed material parameters have been accounted for.

Reversible, suction based adhesion employed by many marine organisms may provide unique, adaptable technologies for biologically inspired grasping devices that function in difficult submerged environments. Here a theoretical framework based on measurable structural, material, and topological properties is developed to better understand a critical aspect of suction based attachment strategies: the leakage rate. The utility of the approach is demonstrated on an experimental apparatus designed to mimic the flow conditions experienced by a suction-based attachment device. Furthermore, the sealing effectiveness of a remora fish on sharkskin is investigated as a biological example.

Recent nuclear forensics cases have focused primarily on plutonium (Pu) and uranium (U) materials. By definition however, nuclear forensics can apply to any diverted nuclear material. This includes neptunium (Np), an internationally safeguarded material like Pu and U, that could offer a nuclear security concern if significant quantities were found outside of regulatory control. This case study couples scanning electron microscopy (SEM) with quantitative analysis using newly developed specialized software, to evaluate a non-traditional nuclear forensic sample of Np. The results of the morphological analyses were compared with another Np sample of known pedigree, as well as other traditional actinide materials in order to determine potential processing and point-of-origin.

We here report the fabrication of high-quality nanostructured electrodes based on surfactant-capped ITO colloidal nanocrystals and their implementation in self-powered bi-functional smart devices which are simultaneously capable of generating electric energy as a photovoltaic system as well as of controlling the intensity of incoming thermal radiation by means of a smart variation of their optical transmittance. A reversible modulation of the solar transmittance in the NIR range higher than 60% has been experimentally demonstrated.

Here, we report the controllable fabrication of transparent conductive films (TCFs) for moisture-sensing applications based on heating-rate-triggered, 3-dimensional porous conducting networks of single-walled carbon nanotube (SWCNT)/poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS). How baking conditions influence the self-assembled microstructure of the TCFs is discussed. The sensor presents high-performance properties, including a reasonable sheet resistance (2.1 kohm/sq), a high visible-range transmittance (> 69 %, PET = 90 %), and good stability when subjected to cyclic loading (> 1000 cycles, better than indium tin oxide film) during processing. Moreover, the benefits of these kinds of TCFs were verified through a fully transparent, highly sensitive, rapid response, noncontact moisture-sensing device (5×5 sensing pixels).

A new organometallic halide perovskite (OHP) synthesis method, whereby a polymer melt is used to thermodynamically drive the reaction that forms OHP crystallites, is demonstrated. The synthesis method allows for the facile encapsulation of moisture-sensitive OHP without the loss of simplicity during fabrication, which makes OHP materials so attractive for the photovoltaic industry. Degradation of OHP crystallites embedded in a polystyrene matrix was studied using UV-Vis absorbance over a period of several days. The OHP crystallites degrade as a result of the reversible nature of the reaction that forms the crystallites. After the reversion to precursors (PbI2 and CH3NH3I) the CH3NH3I irreversibly degrades [2] allowing the degradation to be tracked via optical interrogation. Additionally, surface morphology and elemental analysis of fabricated samples was carried out using SEM/EDS techniques.

Tin(Sn) and its alloys have been attracting attentions as a negative electrodematerial for sodium-ion secondary batteries with high theoretical capacity(Na15Sn4, ca. 847 mAh/g) and highelectromotiveforce. There still remains the issue as regards the dischargecapacity decrease with increasing the number of cycles. In order to improvecycle performance, there are many studies such as using Sn-Ni alloy, however,using Sn based alloy as negative electrode materials and it suffer from thedisadvantage of lowering of discharge capacity. In this study, a depositionprocess for making Sn film which consists of amorphous structure for negativeelectrode of sodium ion secondary batteries utilizing electordeposition fromaqueous bath was developed. The effect of additives on the surface morphologyand microstructure of Sn film was investigated. Furthermore, we evaluated theeffect of amorphous structure in the Sn film on cycle performance of the Snnegative electrode. Sn film has a good cycle characteristic (>50cycles) and discharge capacity (> 400 mAh/g). Amorphous structure inthe Sn film showed a microscopic effect on the volume change by sodiation anddesodiation.

This paper introduces the design and simulated operation of a capacitive hydration sensor for integration into textile-based electronics. The multilayer patch is composed of a textile layer and an attached series of serpentine-interdigitated electrodes. The model used for simulations incorporated this design onto a representative model of skin. The serpentine-interdigitated electrodes are electrodes for capacitive measurement of skin hydration. In this study, the capacitance change relative to skin hydration was simulated using finite element analysis. The simulation results suggest the fabric layer had little effect on the capacitance of the sensor. Furthermore, the frequency domain simulations indicated that the capacitance of the sensor decreased with increasing frequency, and the decrease in capacitance was more significant for the dry skin compared to the wet skin. Therefore, the variation in the capacitance value of the serpentine-interdigitated electrodes can be employed for continuous skin hydration detection.

Copper Indium Sulfide (CIS)-based quantum dots (QDs) are considered as a safer alternative compared to carcinogenic cadmium- and lead-based QDs. Here, we present a facile, high throughput, and non-injection method of synthesizing CIS-based QDs. The structure, shape, size, and crystalline structure of the synthesized QDs were studied using high resolution transmission electron microscopy (HRTEM). The effects of temperature and compositional dependency on the structure and optical properties of the resulting QDs were investigated using elemental, absorption, photoluminescence (PL), and time-resolved spectroscopic analyses. We observed that a gradient increase of temperature during the core growth, as well as addition of excess indium (In) and zinc (Zn) precursors during core and core/shell synthesis, at low growth temperatures, resulted in QDs with improved PL and lifetime. The large Stokes shift, broad emission spectra, and long-lived emission of the synthesized QDs reveal their potential applicability to third generation photovoltaic and optoelectronic devices.

While graphene has unique electrical and mechanical properties, it is not soluble in most common solvents. Partially reducing graphene oxide (prGO) will remove some of the functional groups while still maintaining solubility, producing an intermediate between graphene oxide and reduced graphene oxide. This research investigated the properties of prGO as well as those of prGO sheets incorporated with gold and platinum nanoparticles (Au/Pt-prGO) using FTIR, Raman, TEM and HRTEM.

The multiferroic material YbMnO3 has been reported to exhibit bothferroelectric and antiferromagnetic orders in the ground state. Of these twoorders, the ferroelectric order is associated with theP63/mmc-to-P63cm structural transition, which occursaround 1270 K. The interesting feature of the ferroelectric state is that acloverleaf domain structure with a pseudo-six-fold symmetry is observed intransmission electron microscopy images with the beam incidence parallel to thehexagonal axis. To understand the origin of the formation of the cloverleafdomain structure, we have examined the crystallographic features of theferroelectric state in YbMnO3 by transmission electron microscopy. Inthis study, particularly, we adopted the experimental condition that electronbeam incidences are perpendicular to the hexagonal axis. It was, as a result,found that there existed various ferroelectric domain structures including thecloverleaf domain structure under the present condition. The notable feature ofdomain structures found in this study is that each domain structure basicallyconsists of six domains, whose domain boundaries are terminated at one point.Because this feature makes us reminiscent of a discommensurate structure in anincommensurate state, we took high-resolution electron micrographs of areasincluding domain boundaries. Their analysis indicated that a domain boundarycould be identified as a discommensuration with a phase slip of π/3.It is thus understood that the cloverleaf domain structure should be one ofdomain morphologies for a discommensurate structure, which is related to thebreak of the translational symmetry.