The perovskite catalysts La0.75Sr0.25Cr0.5X0.5O3±δ (where X= Mn, Fe and Co) were prepared by combustion synthesis and the influence of transition metals B-site substitution on the structural and catalytic properties of the catalysts in steam reforming of both pure and by-product glycerol to produce hydrogen-rich gases for utilization in solid oxide fuel cell was investigated. All the catalyst systems were found very active and selective with the Fe-substituted catalyst slightly more active. Hydrogen yield and coke suppression was better in the Mn-substituted catalyst which was also structurally more stable in fuel environment. Impregnation of Ni into the lattice structure of the pre-reacted both A-site and B-site stoichiometric catalysts from nickel nitrate solution and subsequent redox exsolution of Ni nano particles supported on the oxide surface of the materials has significantly improved the hydrogen yield by enhancing water-gas-shift reaction (WGSR). Thus, extent of the exsolution phenomenon observed in the materials followed the order LSCM > LSCC > LSCF.

Glasses are recognized as the ideal hosts to incorporate plasmonic metal nanoparticles (NPs), semiconductor NPs, and luminescent rare-earth (RE3+) ions. This is due to their unique optical properties, stability, absence of high energy bond vibrations and inertness towards the incorporated NPs. However, conventional methods of metal-glass nanocomposite fabrication involve ion-implantation or sputtering and subsequent heat-treatment under H2, UV-light/X-ray/γ- or laser irradiation. They are (i) multi-step, (ii) require expensive set-up, (iii) bear risk of sample damage and (iv) the formation of NPs occurs only in surface layers. Here we develop two novel glass-systems K2O-B2O3-Sb2O3 and K2O-B2O3-Sb2O3-ZnO. Using the selective reducing property of the main component Sb2O3 in these hosts, here we demonstrate for the first time the strategy for single-step in-situ fabrication of metal (M0) NPs and RE3+ ions co-embedded within bulk glasses. This new series of novel composites co-embedding metal NPs (elliptical Au, elongated Ag NPs and Aucore-AuAgshell NPs) and RE3+ ions exhibit enhanced upconversion for solar panels, advanced displays and other nanophotonic applications. Metal NPs exhibit surface plasmons resonance results in concentration and enhancement of the local electromagnetic field (LFE) around them. The luminescent RE3+ ion in the vicinity experiences the local field effect. We observe that the LFE effect is stronger on electric dipole transitions of the RE3+ than the magnetic dipole ones. LFE induced by nano Au enhance the (i) 4G7/2 → 4I9/2 540 nm green and 4G7/2 → 4I15/2 650 nm red upconversion emissions of Nd3+ by 9 and 11 fold, (ii) electric dipole 4G5/2 → 6H9/2 636 nm red upconversion of Sm3+ by about 7 fold and (ii) 4S3/2 → 4I15/2 536 nm green and 4F9/2 →4I15/2 645 nm red emissions of Er3+ by 2 and 5 fold respectively. LFE induced by nano Ag enhance both the green and red upconversion emission of Er3+ by 8 fold. The Aucore-AuAgshell NPs enhance the red upconversion of Sm3+ only by 2 fold due to smaller LFE effect of bimetallic NPs. All the Au-doped antimony glasses are dichroic. They transmit the blue light and reflect the brown light, which make them very interesting material comparable to the historic Lycurgus Cup.

Research Experiences for Undergraduates (REU) programs traditionally function as a recruitment vehicle to encourage students to pursue further studies in STEM (Science, Technology, Engineering and Math) and as an opportunity for STEM majors to delve deeper into their chosen fields of study. Based on a critical examination of REU student feedback, evaluators at CRISP (Center for Research on Interface Structures and Phenomena) have found that in addition to these conventional benefits of research-based experiences, the value of interdisciplinary skill development is integral to the REU experience and these contributions may warrant a more formal evaluative definition. Using the emerging 21st Century Skills Framework, CRISP has begun conducting a series of small-scale studies in an effort to define the contribution of student research experiences in cross-disciplinary skill development and the positive effects that exposure to real-world science practices have on refinement of career decisions and vocational success. Using Likert-type survey methods, this study directly examines current and former REU students’ perceptions of the importance of interdisciplinary 21st century skills such as creativity, collaboration, communication, information literacy, and problem-solving in their REU experience and their perceived value of these skills in their future and/or current careers. Through better understanding the role these “soft skills” play in student research experiences, CRISP hopes to maximize these interdisciplinary benefits within its REU program to best prepare students for the complex demands of the 21st century workplace.

In this work, we have reported the interface characterization of rf sputtered ZnO/HfO2 in thin film transistor structure by dc current-voltage and admittance spectroscopy. The interface state density (Dit) of 1013 eV−1cm−2 was extracted from the Gp/ω vs ω plot was comparable to value obtained from the subthreshold behavior. The grain boundary trap density (NGB) of 9.12×1012 cm−2 was estimated using Levinson’s model. The interface state density distribution below the conduction band edge shows a decreasing trend with energy below the conduction band edge. We also studied the impact of introducing MgO interfacial layer between ZnO and HfO2 interface as an approach towards decreasing the interface state density.

Poly(acrylamide-co-2-hydroxyethyl methacrylate), hydrogel microparticles were prepared by free radical copolymerization of acrylamide (AAm) and 2-hydroxyethyl methacrylate (2-HEMA) using an inverse emulsion polymerization technique, employing ethylene glycol dimethylacrylate (EGDMA) as crosslinker in the presence of w/o emulsifiers span-80 and span-85 (sorbitol mono-oleate) above the lower critical solution temperature. Water absorption capacity and characteristics of the hydrogel microparticles were analyzed by Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). Thus, microparticles were submitted to a gravimetric study on their ability to absorb and to retain distilled water at 25°C. One gram of microparticles absorbed at least 15 g of water. By varying the relative ratio between the continuous phase (hexane and emulsifiers) and the dispersed phase (monomers, initiator and crosslinker), non-agglomerated dispersed particles with nearly spherical shape were obtained having a narrow size distribution in the range from 10 to 20 µm. At a constant value of the emulsifier, and as a result of increasing the stirring rate, a particle size reduction was observed from 13 to 7 µm. The PAAm and PHEMA structures of synthesized hydrogel were confirmed using FTIR analysis. Additionally, through thermal analysis the P(AAm-HEMA) hydrogel showed an increase of water retention and thermal stability due to PAAm addition.

This paper reports low temperature, digital control, fast synthesis of high-quality boron nitride nanosheets (BNNSs) and their electronic device application. Raman scattering spectroscopy, X-ray diffraction (XRD), Transmission electron microscopy (TEM) are used to characterize the BNNSs. With the synthesized various BNNSs, two prototypic types of deep UV photodetectors have been fabricated, and sensitivity, response and recovery times, as well as repeatability have been characterized. Effects of period and thickness of BNNSs on the properties of prototypic photodetectors are also discussed.

Performance of a perovskite based solar cell is highly determined by the crystalline qualities of the perovskite thin film sandwiched between an electron and a hole transport layer, such as grain size and uniformity of the film. Here, we demonstrated a new hybrid physical-chemical vapor deposition (HPCVD) technique to synthesis high quality perovskite films. First, a PbI2 precursor film was spin-coated on a mesoporous TiO2 (m-TiO2)/compact TiO2 (c-TiO2)/FTO substrate in ambient environment. Then, purified CH3NH3I crystal material was evaporated and the vapor reacted with the PbI2 precursor film in a vacuum pressure/temperature accurately controlled quartz tube furnace. In this technique, high vacuum (2mTorr) and low temperature (100°C) were applied to decrease perovskite film growth rate and reduce perovskite film defects. After vapor reaction, the perovskite film was annealed at 100°C for 10min in 20mTorr vacuum to recrystallize and remove CH3NH3I residue in order to further improve crystal quality of the thin film. Crystal quality of this perovskite thin film was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). SEM and AFM results illustrate perovskite thin films synthesized by this technique have larger grain sizes and more uniformity (RMS 11.6nm/Ra 9.3nm) superior to most existing methods. Strong peaks shown in the XRD chart at 14.18°, 28.52°, 31.96°, which were assigned to (110), (220), (330) miller indices of CH3NH3PbI3 perovskite crystal, indicate the complete reaction between CH3NH3I vapor and PbI2 precursor layer. High power conversion efficiency (PCE) up to 12.3% and stable efficiencies under four hours illumination of AM1.5 standard were achieved by these solar cells. This vacuum/vapor based technique is compatible with conventional semiconductor fabrication techniques and high quality perovskite film could be achieved through delicate process control. Eventually, perovskite based solar cells could be mass produced in low cost for large scale applications by this novel technique.

This paper focuses on the impact of process parameters of gas metal arc welding (GMAW) on the mechanisms of fail and wear present in the contact tips (CT), component located in the welding gun, when high strength low alloy (HSLA) steel is welded with ER70S - 0.045” copper coated electrode in manual mode. By means of chemical analysis the alloy was identified as C12200. It was also identified that the maximum temperature reached by the CT is 850° C. 30 samples were obtained that had different lifetime, which were analyzed by stereoscope and its behavior against wear was determined by using an equation of relative wear. Microstructural changes as recrystallization and grain growth undergone by these CT were also evidenced by light microscopy. In addition the changes in their mechanical properties such as decrease in their hardness to about of half that initially had. Finally some significant samples were analyzed by scanning electron microscopy (SEM); microanalysis was used to identify the exchange of matter leaving from the electrode in the CT and spatter into the hole of the component.

Alumina matrix solidification is a hot isostatic pressing (HIP) technique used to immobilize radioactive iodine (129I) in the form of silver iodide. In the present study, an alumina matrix solidification sample with a porosity of 12.9% was obtained by performing HIP at 175 MPa and 1200°C for 3 hours on a simulated spent silver-sorbent saturated with stable iodine. Material Characterization Centre-1 (MCC-1) leaching tests for the simulated waste form were performed using hydrosulfide (HS-) as a reductant at concentrations ranging from 3 × 10-7 M to 3 × 10-3 M and at pH values ranging from 8.0 to 12.5. Leached iodine concentrations were below the detection limit for ICP-MS measurements at HS- concentrations of 3 × 10-7 M and 3 × 10-5 M. This result was due to the stability of AgI. At an HS- concentration of 3 × 10-3 M, iodine leaching rapidly increased within 10 days. The maximum iodine concentration in the solution was 4.33 × 10-3 M, which corresponds to 85% dissolution of the initial iodine. This value was measured after 552 days under an HS- concentration of 3 × 10-3 M at pH 11. An analysis of specimen cross-sections suggested the following reaction: 2AgI + HS- = Ag2S + 2I- + H+. The pH affected matrix aluminum dissolution but did not significantly affect the iodine leaching behavior. Furthermore, the normalized mass loss of iodine was larger than that of aluminum by a factor greater than 104, which is due to the large porosity and the dissolution of interior AgI of the solid.

This paper explores the relationship between digital and material-based fabrications in architecture. The notion of transient materialization proposes that immaterial architecture is a trigger for investigating new possibilities for digital fabrication through space and time. This project is mainly inspired by the beauty of nature, focusing on soap foam bubbles, which have an n-hedron structure and are usually blown by air. The paper questions this structure’s materiality, examines its physical performance and ephemeral characteristics, and expands on its meaning through an experiment in digital fabrication. In addition, we present the first phase of this technology, in which an anti-gravity and programmable foam structure was achieved. The experiment demonstrates the different shapes possible for dynamic and transient soap foam structures.

Cerium oxide is an important electrode material in fuel cells. It has been interconverted in the gaseous phase at high temperatures or in the presence of oxygen and more recently in the solid state by applying an electric field. In the dynamic change that occurs, the migration of oxygen vacancies have been initiated at a critical potential of 2.8 V. We wish to report here an electrochemical method where the conversion of cerium oxides is brought out in aqueous medium where hydrogen ion is assisting the process of conversion. Keeping dissolved oxygen level negligible, the conversion of Ce2O3 to CeO2 occurs at 0.72 V vs saturated calomel electrode (SCE) with hydrogen ion assisting the process and the reversible conversion at 0.15 V (SCE). The hydrogen ion assisted conversion is compared with the solid state conversion that operates on oxygen vacancy creation.

Temperature-memory effects in polymers under stress-free conditions are typically limited to one way effects. Recently, crosslinked polymer networks comprising crystallizable domains, which were capable of a reversible temperature-memory effect (rTME) under stress-free conditions, were introduced. The utilization of crystallizable actuator domains (AD) and shape determining domains (SD) where related to two different temperature ranges of a single broad melting temperature transition in case of rTME. In this study we investigated the nanostructure of crosslinked poly[ethylene-co-(vinyl acetate)] cPEVA capable of rTME in situ during actuation cycles utilizing X-ray scattering techniques and related the changes on the nanoscale to effects on the macroscopic scale. It was observed that 23% of SD obtained at a separation temperature of 75 °C gave the highest reversible strain and when exceeding 80 °C only isotropic crystallization occurred and no rTME was observed. Furthermore, distances between oriented crystalline lamellae correlated to the macroscopic actuation during heating-cooling cycles, exhibiting long-periods from 14 to 17 nm as function of temperature.

In this study, we conducted the in-situ observations of the magnetic domain structure change in Nd2Fe14B magnets at elevated temperature by transmission electron microscopy (TEM) / Lorentz microscopy. The in-situ observations in Nd2Fe14B magnets revealed that the magnetization reversal easily occurred at the elevated temperature. At more than 180°C, the magnetic domain wall motion could be observed by applying the magnetic field of less than 20 mT. The motion of the magnetic domain wall was discontinuous and the domain wall jumped to one grain boundary to the neighboring grain boundary at 180°C. On the other hand, the continuous domain wall motion within grain interior as well as discontinuous domain wall motion was observed at 225°C, and some grain boundaries showed still strong pinning effect even at 225°C. The temperature dependence of the pinning effect of grain boundaries would not uniform.

This paper will discuss the structure-property model developed that correlates the tensile modulus to the elastic properties and angular distribution of constituent graphitic layers for carbon fiber derived from a polyethylene precursor. In addition, a high-temperature fiber tensile device was built to enable heating of carbon fiber bundles at a variable rate from 25 °C to greater than ∼2300 °C, while simultaneously applying a tensile stress. This capability combined with synchrotron wide-angle x-ray diffraction (WAXD), enabled observation in situ and in real time of the microstructural transformation from different carbon fiber precursors to high-modulus carbon fiber. Experiments conducted using PAN- and PE-derived fiber precursors reveal stark differences in their carbonization and high-temperature graphitization behavior.

Pin/pin “micromorph” tandem solar cells were manufactured by the industrial production line of Hunan Gongchuang PV Science & Technology Co., Ltd. Based on this kind of solar cells, a n-doped amorphous silicon layer deposited by plasma enhanced chemical vapor deposition technique (PECVD) was inserted between the microcrystalline silicon intrinsic layer and n-doped layer. The result showed that the introduced n-type amorphous silicon layer well improved the solar cells performance by reducing the bad effects caused by microcrystalline silicon growth defects. Compared with the solar cells without inserting the n-doped amorphous silicon layer, the open voltage and efficiency increased remarkably. When the thickness of n-doped amorphous silicon layer is 8nm, the open voltage increased from 72.9V to 73.6V and efficiency increased from 10.63% to 10.74%.

Polyacrylonitrile (PAN) was printed into a nanostructured carbon nanopillar arrays using a quick, simple, and highly efficient method called spin-on nanoprinting (SNAP). The mold used to print PAN nanostructures could easily be reproduced via printing an inverse replica of carbon nanopillar arrays. The as-printed carbon nanopillar arrays were further prepared as supercapacitor electrodes. As a result, these nanostructured carbon electrodes display an order of magnitude enhancement in specific capacitance compared to non-nanostructured carbon electrodes.