Covalent functionalization of reduced graphene oxide (rGO) with the photosynthetic reaction center (RC) from Rhodobacter sphaeroides R26 via click chemistry reaction has been performed. The hybrid system was characterized by flash photolysis and infrared spectroscopy and the RC was found to retain its photoactivity and structural integrity. The strategy is applicable for the fabrication of hybrid bio-electronic devices capable of absorbing and converting solar energy.

Flame spray pyrolysis (FSP) was applied to produce nanopowders of Ti1-xMxO2 and Sn1-xMxO2, where x = 0.05 and M = Nb/Sb, for use as catalyst support materials in PEM fuel cells/ electrolysers. FSP powders in the SnO2-IrO2 system were produced for the same applications. Homogenous particle size distribution (5-20 nm) was demonstrated by TEM, supported by BET and XRD analysis. Whereas two polymorphs were indicated for the Ti-based oxides, the Sb/Nb-doped SnO2 powders were single phase. FSP powders of Mn3O4 intended for supercapacitors were produced and the influence of the precursor/solvent mixtures on the physical and electrochemical properties evaluated.

Periodically arrayed rows of fine Fe2Hf Laves phase particles were found to form in 9Cr ferritic steel. Microstructural observation demonstrates that the particles were formed on cooling through the interphase precipitation on the phase transformation from the δ ferrite to the γ austenite along the eutectoid transformation route of δ → γ+Fe2Hf and subsequently a phase transformation from the austenite to the α ferrite took place. This eutectoid route is expected to be effectively used for improving the long term creep strength of ferritic steels with Laves phase.

Undergraduate students from Engineering, Physics, Geology & Chemistry come together to form multidisciplinary teams as part of an undergraduate research opportunity through a sequence of independent study classes within the Department of Engineering at James Madison University. The undergraduate research groups typically contain students from freshman to senior years, totaling approximately three to eight students per academic year per group. One of the primary objectives is to provide a high-level research experience for undergraduates in a nurturing environment within the academic year. Peer-mentoring is integral piece to the team dynamics. The course sequence that facilitates the research opportunity is constructed in order for students to produce research that can be applied to obtaining a minor in Materials Science. Methodologies employed in the course range from problem-based learning, inquiry-based learning, and collaborative efforts with outside entities. The course objectives are geared towards developing critical & creative thinking, technical writing and oral communication skills through the development of planned action & experiments with data analysis as well as submitting findings to be presented at regional and national conferences.

A comparison between reported analytical results with experimental data of the magnetic flux density on cylindrical tin inclusions of elliptical cross-section embedded in a copper matrix under external thermal excitation is presented. By changing the aspect ratios b/a designated by e of the elliptical inclusions, a wide range of real situation such as slender inclusions can be simulated. The experimental magnetic field distribution illustrated the potential for the non contacting thermoelectric technique to detect and characterize metallic inclusions of different geometries based on their magnetic signature. Preliminary results on a cylindrical hard alpha (TiN) inclusion embedded in Ti–6Al–4V matrix is also presented to demonstrate that the proposed non-destructive method might be applicable to a wide range of alloys including high-strength, high-temperature engine materials.

Alkaline earth aluminosilicate glasses (AeAS) with different MoO3 additions have been produced and assessed. MoO3 solubility increases with the equimolar substitution of smaller to larger alkaline earths and reaches 5.34 mol% in magnesium aluminosilicate glass (MAS). All visibly homogeneous glasses are X-ray amorphous, while the partially crystallised glasses exhibit some small X-ray diffraction peaks which are probably due to corresponding molybdates. The addition of MoO3 decreases glass transition and crystallisation temperatures and creates two broad Raman bands which are assigned to vibrations of MoO4 2‒ tetrahedra. The intensities of these bands increase along with MoO3 incorporation until the maximum solubility is reached. Electron microscopy shows that these separated particles are spherical, with sub-micron diameters and are randomly dispersed within glass. The separated phases are formed through liquid-liquid separation and thereafter crystallisation. Overall AeAS glasses look quite promising for molybdate immobilisation with MAS glasses being particularly attractive.

Surfactant-free SnS nanoparticles were synthesized using continuous spray pyrolysis (CoSP) technique and used as sensitizers on electro-deposited ZnO nanowire arrays for fabrication of extremely thin absorbing (ETA) layers. The high-surface-area nanowire layer on ITO substrate was directly over-coated by SnS nanoparticles. The morphology of the ZnO/SnS nanostructures showed the coverage of orthorhombic SnS nanocrystals on hexagonal ZnO prismatic nanowires. The crystalline phase of the ZnO/SnS nanostructures was studied using X-ray diffraction. Conducting AFM showed a nonlinear characteristics confirming the junction formation.

We have studied electrochemical Li deposition/dissolution processes at amorphous solid electrolyte (LiPON) interfaces with 30-nm-thick-Cu-current collectors at different current densities by in-situ scanning electron microscopy (SEM). When the current density is smaller than 300 μA cm−2, Li islands continue to grow under a Cu film without coalescing with their neighbors. Consequently, they produce small cracks in the Cu film leading to isolated Li rod growth from the cracks. On the other hand, a current density of 1.0 mA cm−2 provokes the nucleation of Li islands with a higher number density. They rapidly coalesce under a Cu film in all lateral directions before cracking the Cu film. High current density conditions therefore suppress Li rod growths.

A generalized route encompassing a facile hybrid physical/chemical approach is reported for fabricating size and shape selective nanowires of technologically important ferroelectric perovskite oxides (Pb(Zr0.52Ti0.48)O3 (PZT) and Pb-free ZnSnO3) on industrially feasible large-area substrates. The approaches involve depositing nano-seed layers (50 - 100 nm in thickness) of the desired materials (Ti for PZT and ZnO for ZnSnO3) by pulsed laser deposition and RF sputtering techniques followed by oriented growth of nanowire arrays of these materials by solvothermal processes by varying solvent compositions and ratios. Similar crystal symmetry between the seed-layers facilitated the growth of well-aligned nanowire arrays of the targeted materials homogeneously on the substrates with a high packing density. Measurements of the electronic (field-emission), and ferroelectric properties of the materials are performed and discussed in terms of understanding their potential for future technological applications. The facile, low-cost method for fabricating high quality nanowires may expand the outreach of probes for understanding the structure-property relations in other perovskite materials.

Composites of silicone rubber and vertically-aligned carbon nanotubes were produced by capillary infiltration of PDMS. The electrical properties of silicone membranes and carbon nanotubes were investigated by impedance spectroscopy. Gauge factor was evaluated by different ways from Nyquist plots, and reached values up 8.

Titanium oxide photoelectrodes have been used for water splitting for a few decades, but have low solar-to-hydrogen efficiencies. Perovskite halides (e.g., CH3NH3PbI3) have recently emerged as an efficient light absorber system. We try to combine the two materials to create new photoelectrodes to achieve a higher efficiency for hydrogen production. The photoelectrodes are investigated for water-splitting hydrogen production under Xe light irradiation by photoelectrochemical (PEC) reaction. Since perovskite halides are favorable light harvesters under UV and visible light irradiation, the composite films of titania and perovskite halide would achieve efficient water splitting. The hydrogen production rate using the composite films is higher than that using anatase TiO2 electrode. However, the composite films are not stable in water under light irradiation and the perovskite halide gradually decomposes into lead halide.

Chemical and structural characterization of four representative samples of an ore deposit located in the eastern of Hidalgo State was carried out. According with the results, it could be appreciate some areas showing silicified zones with abundant amounts of disseminated pyrites that are part of a rock unit from early Jurassic consisting in inter - bedded black shales and sandstones. Thus, the contents of base metal were greater than 30 ppm Zn and 9 ppm Cu. Chemical analysis of rock gave the following results; 82 ppm of Ba, 1.64 % Wt. Fe, 0.08 % Wt. Ti, 40.8 % Wt. Si, 20 ppm of Ce, 2.2 ppm Co, 30 ppm Cr, 2.7 ppm Cs, 0.9 ppm Er, 2.5 ppm Ga, 1.6 ppm Gd , 1.5 ppm Ge, 9 ppm La, 71 ppm Li, 104 ppm Mn, 10 ppm Nd , 17 ppm Rb, 2 ppm Se, 9 ppm Sr, 10 ppm Ta, 6 ppm Te, 28 ppm V, 9 ppm Y, and 0.7 ppm Yb, among others. Finally, the values found for precious metals, were; Au < 0.02 ppm, Pd <0.05 ppm, Pt <0.05 ppm. It was inferred that the low content of base metals in outcrop studied, are due to the alteration of the black shales. According to these results, we can consider a stratiform – type mineralization of Pb-Zn which could be prospective for SEDEX – Type deposit. By means of XRD, it was possible to identify; pyrite, chalcopyrite, pyrrhotite, and minor amounts of sphalerite and Co -Ni arsenide.

The storage and transportation barriers of hydrogen are cleared by sodium metal “Source of Hydrogen” produced from warm seawater discharged at the nuclear power plant. The warm seawater is electrolyzed to produce sodium hydroxide; which is then subjected to molten-salt electrolysis by surplus power of the plant to produce sodium metal “a hydrogen generator”. The seawater contains salt most after fresh water; which is the raw material of sodium metal and is never drained. The sodium metal is transported to the electric power station in a consumption place, where a large amount of hydrogen is generated immediately by adding water on the sodium metal for power generation. Salt, the raw material of sodium metal, is in the sea over the world, and it is not necessary to worry about the maldistribution and exhaustion.

A number of applications call for the organization of resistive non-volatile memory (NVM) into large, densely-packed crossbar arrays. While resistive-NVM devices often possess some degree of inherent nonlinearity (typically 3-30× contrast), the operation of large (>1000×1000 device) arrays at low power tends to require large (> 1e7) ON-to-OFF ratios between the currents passed at high and at low voltages. Such large nonlinearities can be implemented by including a distinct access device together with each of the state-bearing resistive-NVM elements. While such an access device need not store data, its list of requirements is almost as challenging as the specifications demanded of the memory device.

We review our work on high-performance access devices based on Cu-containing Mixed-Ionic-Electronic Conduction (MIEC) materials [1–7]. (This version focuses only on the MIEC-based access device itself; previously-published longer versions of this work [8–10] also include more extensive surveys of competing devices as well.) These devices require only the low processing temperatures of the Back-End-Of-the-Line (BEOL), making them highly suitable for implementing multi-layer crossbar arrays. MIEC-based access devices offer large ON/OFF ratios (>1e7), a significant voltage margin Vm (over which current < 10nA), and ultra-low leakage (<10pA), while also offering the high current densities needed for PCM and the fully bipolar operation needed for high-performance RRAM. Scalability to critical dimensions (CD) <30nm and thicknesses <15nm, tight distributions and 100% yield in large (512kBit) arrays, long-term stability of the ultra-low leakage states, and sub-50ns turn-ON times have all been demonstrated. Numerical modeling of these MIEC-based access devices shows that their operation depends on Cu+ mediated hole conduction. Circuit simulations reveal that while scaled MIEC devices are suitable for large crossbar arrays of resistive-NVM devices with low (<1.2V) switching voltages, a compact vertical stack of two MIEC devices in series could support large crossbar arrays for switching voltages up to 2.5V.

In this work, Polyaniline (PANI) was used as a sensing film for pH measures due to its characteristic of switching protonation states under acid and alkaline solutions. Equally produced films had their sensitivity (electric response versus pH) measured before and after being under the influence of a constant electric potential (from 3.5 to 6 V, one for each film) for the analysis on how the electric potential influenced the sensitivity. Then, the protonation caused by the application of the first potential was reversed by applying a constant 5 V reverse potential and the sensitivity was then evaluated again. The results show, on average, a constant relation between intensity of protonation and the potential applied and that the process of protonation is reversible by applying a higher opposite potential then the protonation one.

We have investigated an influence of positive polarization charges generated at an interface between GaN barrier/p-AlGaN EB (Electron Blocking) layer in a blue-LED. Simulation results suggested that such polarization charges caused an electron overflow from QWs. The simulation results also indicated that sufficient acceptor doping at the interface could neutralize the positive polarization charges and suppress the electron overflow. We then demonstrated the electron overflow caused by the positive polarization charges and its suppression with sufficient Mg doping at the interface by monitoring emissions from an additional second QW inserted between the p-EB layer and the p-GaN layer. Finally we conclude that the contribution of the electron overflow is not significant for the efficiency droop in blue-LEDs.

A new thermal imaging technique is characterized that uses an optically trapped erbium oxide nanoparticle cluster of approximately 150 nm. This technique can measure absolute temperature and has an imaging spatial resolution of the trapped particle. Scanning optical probe thermometry has been used to thermally image a cluster of gold nanowires that were excited with the trapping laser. Following a deconvolution of the measured thermal profile, a point spread function of the imaging technique has been determined to be a Gaussian with a FWHM of 165 nm. This width is a function of the clustering of Er2O3 nanoparticles used to image the nanowire. Optical probe thermometry has further been used to measure the temperature of nucleation events where a dichotomy of temperature for nucleated water occurs from degassed water and native water. Degassed water has been measured to nucleate at 555K confirming water adjacent to the gold nanoparticle superheats to the spinodal decomposition temperature before nucleating into a water vapor bubble. Following this event, the temperature inside the vapor bubble rises to the melting point of the gold nanoparticle, 1300 K which is followed by temperature stabilization. The rapid and significant temperature increase is attributed to the loss of a thermal dissipation pathway, to the surrounding water, previously available to the gold nanoparticle due to the insulator nature of the growing vapor envelope around the gold nanoparticle.

A new class of graphene–polyselenophene (PSe) hybrid nanocomposite was successfully synthesized using an in situ synthetic method. The synthesized graphene–PSe nanocomposite exhibited unique properties including a large voltage window, high conductivity, and good mechanical properties. The graphene–PSe nanohybrid reduced the dynamic resistance of electrolyte ions and enabled high charge–discharge rates, thereby enabling high-performance supercapacitance. The results were attributed to synergetic effects between graphene and conducting polymers (CPs), which enhanced charge transport, surface area, and hybrid supercapacitance by combining the properties of electrolytic double-layer capacitors (EDLCs) with those of psedocapacitors. Additionally, a flexible supercapacitor based on the graphene–PSe nanohybrid was successfully demonstrated. To fabricate binder-free supercapacitors, chemical vapor deposition (CVD) and vapor deposition polymerization (VDP) methods were employed. The fabricated all-solid-state supercapacitor exhibited outstanding mechanical and electrochemical performance, even after several bending motions. The novel graphene–PSe nanocomposite material is promising for new energy storage and conversion applications.