First-order-reversal-curves (FORCs) are an elegant, nondestructive tool for characterizing the magnetic properties of materials comprising fine (micron- or nano-scale) magnetic particles. FORC measurements and analysis have long been the standard protocol used by geophysicists and earth and planetary scientists investigating the magnetic properties of rocks, soils, and sediments. FORC can distinguish between single-domain, multi-domain, and pseudo single-domain behavior, and it can distinguish between different magnetic mineral species [1]. More recently, FORC has been applied to a wider array of magnetic material systems because it yields information regarding magnetic interactions and coercivity distributions that cannot be obtained from major hysteresis loop measurements alone. In this paper, we will discuss this technique and present high-temperature FORC results for two magnetic nanoparticle materials: CoFe nanoparticles dispersed in a SiO2 matrix, and FeCo-based nanocrystalline amorphous/nanocomposites.

To classify the chemical form of stable carbon released from unirradiated stainless steel, which is the material used to simulate irradiated stainless steel, under highly alkaline and low-oxygen conditions, type 304 and 316 stainless-steel powders were immersed in 0.005 M NaOH solution. Gas and liquid samples were analyzed to identify the chemical form of carbon released from the stainless steel. The liquid samples were divided into unfiltered and filtered samples. In the gaseous phase, hydrocarbons such as methane and ethane were not detected. In the liquid phase, carboxylic acids (formic and acetic acids) were detected. However, the sum of the carbon concentrations of the carboxylic acids was significantly lower than the total organic carbon (TOC) concentration in the unfiltered samples. In the filtered samples, the TOC concentration was closer to the sum of the carbon concentrations than that for the unfiltered samples. In addition, the concentrations of the metallic elements (particularly Fe and Cr), which are the main constituents of the stainless steels, tended to decrease upon ultrafiltration. This suggests that the sorption of carbon on metallic compounds (e.g., colloidal iron hydroxide) may have occurred.

Enhancing the light absorption and improving the charge collection are considered as two major prerequisite for achieving highly efficient bulk heterojunction organic solar cells (BHJ OSCs). In the present study, we have explored Ga doped ZnO as an electron transport layer for improving the charge collection in one of the promising donor: acceptor system comprised of Poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b’]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)] (PTB7-Th):phenyl-C71-butyric acid methyl ester (PC70BM). With the inverted geometry having a configuration of ITO/GZO (40nm)/PTB7-Th: PC70BM (100nm)/MoO3 (10nm)/Ag (100nm), maximum power conversion efficiency (PCE) of 7.24% has been achieved, while it is limited at 6.89% for devices with undoped ZnO.It was found that PCE can be further improved to 8.35 % after V-grooved textured PDMS films were attached to the backside of OSC substrates. We attribute this performance enhancement in OSCs is due to increased total optical path length of the incident light within the device.

Terbium and ytterbium co-doped aluminum oxynitride thin films were grown onto silicon substrates using radiofrequency magnetron sputtering. Aluminum oxynitride samples doped with 4.6 at. % of Yb3+ and co-doped with 0.4 at. % of Tb3+ were obtained. The prepared samples were annealed from 150°C to 850°C in steps of 100°C. By using energy dispersive X-ray analysis we measured the sample composition and the doping concentration. The emission intensities at different annealing temperatures were characterized using photoluminescence measurements upon excitation at 325 nm. The 5D4 → 7F5 main transition of Tb3+ and the characteristic near infrared emission at 980 nm of Yb3+ were recorded. In order to study the luminescence behavior of the samples in terms of a down conversion process, we have plotted the integrated areas of the main transition peaks versus the annealing temperature.

The oxide interface SrTiO3/LaAlO3 supports a 2D electron liquid displaying superconductivity and magnetism, while allowing for a continuous control of the electron density using a gate. Our recent measurements have shown a similar surprising nonmonotonic behavior as function of the gate voltage (carrier density) of three quantities: the superconducting critical temperature and field, the inverse Hall coefficient, and the frequency of quantum oscillations. While the total density has to be monotonic as function of gate, the last result indicates that one of the involved bands has a nonmontonic occupancy as function of the chemical potential. We show how electronic interactions can lead to such an effect, by creating a competition between the involved bands and making their sturcture non-rigid, and thus account for all these effects. Adding Fock terms to our previous Hartree treatment makes this scenario even more generic.

Safety is one of the most crucial problems faced by the lithium-ion battery (LIBs) industry. In this work, we propose a strategy to avoid overcharging of a battery via the application of a solid-state combined cathode. The goal of this research is to produce LIBs with overcharge self-regulation capabilities. In order to achieve self-regulation functionality, 1,4-di-tert-butyl-2,5-dimethoxybenzene (DBB) is added to as-synthesized LiFePO4, post synthesis. DBB has a trigger voltage of 3.9 V. When this voltage is reached, DBB forms a reduced ion that is released into the electrolyte from the cathode side. The DBB ion transfers to the anode side where it oxidizes and transfers back to the cathode side. This process forms a redox shuttle and consumes the extra charges keeping the voltage at a safe level (i.e. 3.9 V). The DBB redox shuttle protects the LiFePO4-based LIBs with working voltage between 3.4 and 3.5 V. The cycleability of assembled batteries is tested using an Arbin Tester.

We have developed deposition of vertically aligned graphene sheets on Cu foils by surface wave microwave plasma CVD and the transfer from Cu foil to quartz substrate to evaluate optical reflectances and transmittances of the inherent vertical aligned graphene sheets. Both reflectance and transmittance spectra are almost independent of incident angles in the range between 300 and 800nm. The reflectance is lower than 0.067%, which is lower than those of the commercial black alumite plate. The transmittances are less than the detection limit of the system. It is considered that the obtained low reflectance is attributed to the unique structure of the vertically aligned graphene sheets.

In this work the electrical performance of a radiation hard designed 1T-1R resistive random access memory (RRAM) device is investigated in DC (voltage sweep) and AC (pulsed voltage) modes. This new device is based on the combination of an Enclosed Layout Transistor (ELT) used as selector device and a TiN/ HfO2/ Ti/TiN RRAM stack used as resistive device. The high cell to cell variability in the DC mode makes it difficult to define an electrical gap between the High Resistive State (HRS) and the Low Resistive State (LRS). The strong reduction of the variability by the use of Incremental Step Pulse with Verify Algorithm (ISPVA) makes the later a mandatory programming approach. The Quantum Point Contact (QPC) model defines an energy barrier located in the rupture point of the filament in HRS. The compensation between the width and height variations of this barrier during cycling could explain the stability of HRS and LRS. The good performance of the proposed device using the ISPVA programming approach makes it a good candidate for Rad-Hard Non Volatile Memories integration.

We have fabricated ZnInON (ZION), which is a pseudo-binary alloy of wurtzite ZnO and wurtzite InN and has a tunable band gap over the entire visible spectrum and a high optical absorption coefficient of 105 cm-1. ZION films grow two dimensionally at Ts = room temperature (RT) and 150°C, whereas they grow three dimensionally at Ts = 250 and 450°C. These films at RT and 150°C show a step-terrace structure with the step height of 0.27 nm, which corresponds to the height of a single-atomic-layer step and the half length of the c-lattice parameter of ZION. ZION film has the same a-lattice parameter of 0.325 nm as ZnO and a longer c-lattice parameter of 0.536 nm, indicating the coherent growth of ZION films on ZnO templates. ZION film grown at RT shows blue (2.89 and 3.08 eV) photoluminescence at RT.

Elemental powders of Cu and Ni, binary alloys (Cu-Ni and Cu-Zr) and ternary alloy (Cu-Ni-Zr) obtained by mechanical alloying and uniaxial compaction hot microstructure and mechanical properties were investigated. The alloys studied were: pure Cu, pure Ni, binary alloys (Cu-Ni; Cu-Zr) and ternary alloys (Cu-Ni-Zr) under the same mechanical milling and hot pressing conditions. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM); the mechanical properties were studied by compression tests and hardness in Vickers scale (HV0.5) on polished surfaces at room temperature. According to XRD results, hot pressing process crystallite size increase and microstrain decreases in the compact samples due to the release of crystalline defects. The compacted samples have porosity of approximately 20%. The milling powder samples have a higher hardness than the unmilled samples, this because during milling crystal defects are incorporated together with the microstructural refinement. Ternary alloy is the one with the highest hardness of all systems studied, reaching 689 HV0.5. In compression tests determined a strain 5 %, Zr-containing samples become more fragile presenting the lowest values of compressive strength. In contrast, samples of Ni and Cu-Ni binary alloy are more resistant to compression.

A preliminary survey of the microstructures and compositions of representative ceramic styles using minimally invasive analytical techniques provides a method of gaining insight into the materials and techniques of ceramic production dating from the eleventh to twelfth centuries C.E. at the archaeological site of Aktobe and from the 14-15th centuries C.E. at Aspara in southeastern Kazakhstan, both walled cities on the Silk Road trading corridor. The case is made for local production based on the argument of technological style or patterning of practices. Seven ceramic sherds representative of glazed earthenware and stoneware traditions were selected for study from excavations of Y. Akimbek and others that are maintained at the Institute of History and Archaeology of the Republic of Kazakhstan in Almaty. Fragments from serving bowls, a cup and bottle were studied by optical microscopy (OM), scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDS), electron beam microprobe analysis (EPMA) and refiring tests of the bodies and glazes. This initial study aims to characterize the range of physical and chemical variability of ceramics either produced at or imported into Aktobe and Aspara. Most stylistic studies consider these ceramics to have been imported from the Silk Road trade routes that connected many Central Asian cities. The styles include an imitation lusterware bowl made with a ground chromite underglaze pigment, a copper turquoise and cobalt blue and black painted white slipped alkaline-glazed cup, two green lead-glazed copper bowls, an imitation three-color of Chinese sansai bowl, a four-color lead-glazed bowl with underglaze mottled red, gray and black painted slips on a white slipped background and a stoneware bottle. Comparison of the weight ratios of the glaze compositions to possible plant ash raw material sources is presented as a possible way of studying raw material variability; however, analysis is complicated by having two other possible sources that may have supplied fluxing agents, including, salts present in the clays and salts from evaporite deposits.

The effect of temperature (5K to 300K) on the Raman scattering due to A1g/A1’ modes associated with the out-of-plane vibrations in bilayer (2L) and trilayer (3L) MoTe2 is investigated. The temperature evolution of the modes critically depends on the flake thickness. The A1g mode intensity in 2L MoTe2 observed with λ=632.8 nm light excitation decreases with decreasing temperature down to 220K and the mode vanishes from the Stokes scattering spectrum in the temperature range between 160K and 220K. The peak recovers at lower temperatures and at T=5K it becomes three times more intense that at room temperature. Similar non-monotonic intensity evolution is observed for the A1’ mode in 3L MoTe2 in which tellurium atoms in all three layers vibrate in-phase. On the contrary, the intensity of the other out-of-plane Raman-active mode in which vibrations of tellurium atoms in the central layer of 3L MoTe2 are shifted by 180° with respect to vibrations in outer layers, only weakly depends on temperature.

The observed quenching of the out-of-plane modes in the Raman scattering in thin MoTe2 layers is related to the destructive interference of the resonant- and the non-resonant contributions to the Raman scattering. The resonance with the M point of the Brillouin zone in few-layers of MoTe2 is considered. Effects related to the resonant quenching of the in-phase out-of-plane mode are discussed.

Among different efforts to increase the competitiveness of lithium-ion batteries (LIBs) in the energy storage marketplace, reducing the cost of production is a major effort by the LIB industry. This work proposes a synthesis method to decrease the production cost for LiFePO4, by synthesizing the material through an open-air environment solid state reaction.

The lithium (Li)-ion battery is a member of the family of rechargeable batteries. In our approach, iron phosphate (FePO4) powder is preheated to eliminate moisture. Once dried, the FePO4 is mixed with lithium acetate (CH3COOLi), and the mixture is heated in a tube furnace. The solid-state reaction is conducted in an open-air environment. In order to minimize the oxidation of the formed LiFePO4, a modified tube reaction vessel is utilized during synthesis. X-ray Diffraction (XRD) and Energy Dispersive Spectroscopy (EDS) are used to characterize the crystal structure and chemical composition of the synthesized material. Furthermore, scanning electron microscopy (SEM) characterization shows the grain size of the formed LiFePO4 to be in the range of 200 nm to 600 nm. Cycling testing of fabricated battery cells using the synthesized LiFePO4 is done using an Arbin Tester.

Because of steady increase in the availability of computing power, ab initio methods of computational materials science become everyday investigation tools in various research fields. This popularity of the first-principle-based atomistic modeling is in large part due to the performance of density functional theory (DFT), which could be used for simulations of chemically and structurally complex materials, including minerals, fluids and melts. However, because of intrinsic approximations, DFT is not always able to deliver reliable predictions. This is especially pronounced for f-elements bearing materials such as nuclear materials considered in nuclear waste management. Properties such as reaction enthalpies or electronic state are often badly predicted. In this contribution we discuss our experience with different computational methods, including the parameter free DFT+U method, in which the Hubbard U parameter is derived ab initio, for prediction of various properties of f electrons bearing materials. We show significant improvement obtained for structural and thermochemical parameters of various lanthanide-bearing ceramic materials and actinide-bearing molecular and solid compounds when the f electrons correlations are explicitly accounted for. Last, but not least, we demonstrate that complementary experimental and atomistic modeling studies result in superior and more complete characterization of challenging materials considered in nuclear waste management.

Molecular dynamics simulations of the melting process of bulk copper were performed using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) with the interatomic potentials being described by the embedded atom method. The aim of the study was to understand the effects of high pressures and defects on the melting temperature. The simulations were visualised using Visual Molecular Dynamics (VMD). The melting temperature of a perfect copper crystal, was found to be slightly higher than the experimentally observed value. The melting temperature as a function of pressure was determined and compared with experiment. Point and line defects, in the form of dislocations, were then introduced into crystal and the new melting temperature of the crystal determined. We find that the melting temperature decreases as the defect density is increased. Additionally, the slope of the melting temperature curve was found to decrease as the pressure was increased while the vacancy formation energy increases with pressure.

In this paper, synchrotron based infrared micro-spectroscopy was utilized to describe the degradation profile of fibroin contained in silk textiles (Bombyx mori). The spatial distributions of deterioration effects in silk samples artificially aged at an assortment of conditions (thermal, hydrolytic and ultraviolet) were distinctly visualised and in accordance with the findings from conventional infrared spectroscopy in references. Further this method was applied on a historic sample from a private collection in Melbourne, and presented consistent results. This established synchrotron IR chemical mapping method could enable museum professionals to better understand the preservation state of historic silk and make informed decisions for conservation.

S-layer proteins of various lattice-forming types are the most abundant protein by mass on earth. They form the outermost cell crystalline component in a broad range of bacteria and archaea. They are porous monomolecular layer with unit cell size in tens of nanometers. These monomer proteins are capable of forming self-assembled mono- or double layers. Isolated from cell surfaces or through recombinant protein production, they are able to form ordered 2D crystal lattice on a variety of non-cellular surfaces. We study S-layer SbpA protein, which is found in mesophilic organism Lysinibacillus sphaericus with square lattice crystallinity. The recombinant SbpA (rSbpA) can be genetically modified and expressed in E. coli in different truncated forms. Using both the wtSpbA and truncated rSbpA, we reproduced the unique two-dimensional self-assembly pattern on several solid or flexible surfaces of interests towards electronic devices. By surface modification we can promote the self-assembly of SbpA on low affinity substrates. This enables a potential mean of creating complex functional bio-nanostructure. Delicate control of the self-assembly processes of S-layer on surfaces also serves the prerequisite of building the supramolecular structure as bio-electronic platform through protein fusing. Understanding of the electrical response from s-layer proteins provides a bridge between biological systems and electronic devices. Scale-up production and understanding the detailed interaction of the S-layer interface will likely be useful for nanobiotechnology and synthetic biology.

Crystallization of aluminosilicates during the conversion of Hanford high-level waste (HLW) to glass is a function of the composition of the glass-forming melt. In high-sodium, high-aluminum waste streams, the crystallization of nepheline (NaAlSiO4) removes chemically durable glass-formers from the melt, leaving behind a residual melt that is enriched in less durable components, such as sodium and boron. We seek to further understand the effect of lithium, boron, and iron addition on the crystallization of model silicate glasses as analogues for the complex waste glass. Boron and iron behave as glass intermediates which allow for crystallization when present in low additions but frustrate crystallization in high additions. In this work, we seek to compare the average structures of quenched and heat treated glasses through Raman spectroscopy, X-ray diffraction, vibrating sample magnetometry, and X-ray pair distribution function analysis. The endmembers of this study are feldspathoid-like (LiAlSiO4, NaAlSiO4, NaBSiO4, and NaFeSiO4), pyroxene-like (LiAlSi2O6, NaAlSi2O6, NaBSi2O6, and NaFeSi2O6), and feldspar-like (LiAlSi3O8, NaAlSi3O8, NaBSi3O8, and NaFeSi3O8). Such a comparison will provide further insight on the complex relationship between the average chemical ordering and topology of glass on crystallization.

Ni base intermetallic alloy coating was fabricated by laser cladding, controlling the laser power and powder feed rate. Atomized powder of the Ni base intermetallic alloy was laser-cladded on the substrate of stainless steel 304. The hardness and microstructure of the clad layers were investigated by Vickers hardness test, SEM, XRD and TEM observations. The hardness of the cladding layer was affected by the dilution with the substrate; it increased with decreasing laser power and increasing powder feed rate. By optimizing the dilution with the substrate, the cladding layer with an almost identical hardness level to that of the Ni base intermetallic alloy fabricated by ingot metallurgy was obtained. The TEM observations revealed that a very fine-sized microstructure composed of Ni3Al and Ni3V was partially formed even in the as-cladded state. After annealing, the two-phase microstructure composed of Ni3Al and Ni3V was developed in the cladding layer, resulting in enhanced hardness in the cladding layers fabricated in the majority of cladding conditions.

Understanding the ratcheting effect of hydrogen and hydride accumulation in response to thermal cycling is important in establishing a failure criterion for zirconium alloy nuclear fuel cladding. We propose a simple discrete dislocation plasticity model to study the evolution of the dislocation content that arises as a micro-hydride repeatedly precipitates and dissolves over a series of thermal cycles. With each progressive thermal cycle, we find a steady growth in the residual dislocation density in the vicinity of the hydride nucleation site; this corresponds to a gradual increase in the hydrogen concentration and, consequently, the hydride population. The simulated ratcheting in the dislocation density is consistent with experimental observations concerning the hysteresis in the terminal solid solubility of hydrogen in zirconium, which can be correlated to the plastic relaxation of hydrides.