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Poster Abstracts 1794-A-1902 Influence of the support on stabilizing local defects in strained monolayer oxide films Shuqiu Wang1, Xiao Hu1, Jacek Goniakowski2, Claudine Noguera2, Martin R. Castell1 1 Department of Materials, University of Oxford, Oxford, U.K. 2 CNRS-Sorbonne Université, Paris, France Two-dimensional materials with a honeycomb lattice, such as graphene and hexagonal boron nitride, often contain local defects in which the hexagonal elements are replaced by four, five, seven, and eight-membered rings. An example is the Stone-Wales (S-W) defect, where a bond rotation causes four hexagons to be transformed into a cluster of two pentagons and two heptagons. A further series of similar defects incorporating divacancies results in larger structures of non-hexagonal elements. In this paper, we use scanning tunneling microscopy (STM) and density functional theory (DFT) modeling to investigate the structure and energetics of S-W and divacancy defects in a honeycomb (2 × 2) Ti2O3 monolayer grown on an Au(111) substrate. The epitaxial rumpled Ti2O3 monolayer is pseudomorphic and in a state of elastic compression. As a consequence, divacancy defects, which induce tension in freestanding films, relieve the compression in the epitaxial Ti2O3 monolayer and therefore have significantly lower energies when compared with their freestanding counterparts. We find that at the divacancy defect sites, there is a local reduction of the charge transfer between the film and the substrate, the rumpling is reduced, and the film has an increased separation from the substrate. Our results demonstrate the capacity of the substrate to significantly influence the energetics, and hence favor vacancy-type defects, in compressively strained 2D materials. This approach could be applied more broadly, for example to tensile monolayers, where vacancy-type defects would be rare and interstitial-type defects might be favored. KEYWORDS: local structural defects, elastic strain, monolayers, two-dimensional materials, ultrathin oxide films, scanning tunneling microscopy (STM), density functional theory (DFT) Reference: S. Wang, X. Hu, J. Goniakowski, C. Noguera and M. R. Castell, Nanoscale, 2019, 11, 2412–2422. 1 1809-A-1902 Indoor organic photovoltaics with high efficiency and flexibility using ZnO/Ag/ZnO-based transparent electrodes TAE GEUN KIM, Byeong Ryong Lee, Kyeng Rock Son, Jae Won Shim Energy harvesting devices such as organic photovoltatics (OPVs), utilizing the energy from the indoor environment, have received great attention owing to the increase in the use of indoor electronic devices. These OPVs have such attractive features as low cost, flexibility, band gap tunability of organic materials, and eco-friendliness, as energy sources. In this study, we fabricated flexible indoor OPVs using ZnO/Ag/ZnO-based transparent conducting electrodes (TCEs). These TCEs provided electrical and optical properties (i.e., a transmittance of 92%, a sheet resistance of 4.8 Ω/sq, and a root-mean squared surface roughness value of 2.1 nm). The OPVs with these ZnO/Ag/ZnO-based TCEs also exhibited further enhanced light absorption and mechanical stability due to the micro-cavity effect and quasi-amorphous structural properties of the ZnO/Ag/ZnO electrode. OPVs fabricated with poly (3-hexylthiophene):indene-C60 bisadduct photoactive layer and the ZnO/Ag/ZnO (40/9/50 nm) electrode showed power- conversion efficiency values of over 12% under a 500 lux luminance of light-emitting diode lamp, which is 20% greater than that of the reference OPVs with typical ITO TCEs. Furthermore, the OPVs exhibited an excellent mechanical stability on flexible polyethylene terephthalate substrates with power-conversion efficiency values of over 10%. 1 1881-A-1902 Dangerous industrial wastewater treatment based on vacuum evaporation technology Feng Han1, Fan Zhao1, Shi-wei Zhang1, De-xi Wang2 1 Northeastern University 2 Shenyang University of Technology At present, some enterprises can not deal with the dangerous industrial wastewater in a cheap and easy way. In view of this situation, we proposed a new method to deal with the wastewater. The method aims to save energy greatly by using a self- designed Double-way Phase Change Heat Exchanger (DPCHE). The DPCHE has a single vacuum-compression pump as the power source. Due to the vacuum effect, the wastewater is evaporated into vapour under the low temperature and low pressure condition. Then the vapour is turned into an overheating steam under the high temperature and high pressure because of the compression. The overheating steam is recirculated in the DPCHE for heat transfer, so the heat is passed from the overheating steam to the wastewater, and overheating steam will condense into clean water. The influence factors (evaporation temperature and compression ratio) on power consumption was also analyzed and verified by the experiment.The experimental results showed that the decrease of the value of above factors can improve the system recovery rate and reduce the power consumption. A set of system design parameters were selected according to the analysis results as the reference for production design. 1 1882-A-1902 Thermodynamic model of the single-stage gradational lead screw vacuum pump used in the chemical engineering Fan Zhao1, Feng Han1, Shi-wei Zhang1, Zhi-jun Zhang1 1 Northeastern University Compared with the constant lead screw (CLS) vacuum pump, the gradational lead screw (GLS) vacuum pump, widely used in the chemical engineering, has the advantage of heat dissipation and saving energy. A thermodynamic model can provide a well explanation on these phenomena. The single-stage GLS (SGLS) vacuum pump is suitable for mass production owing to the simple construction and easy manufacture. Taking the SGLS vacuum pump as the research object, this paper divides the pumping process into four successive stages and proposes a thermodynamic model to analysis quantitatively. The characteristic curves of thermodynamic parameters are drawn and explained in detail. Moreover, the power consumption under diverse operating conditions are plotted and illustrated. The performances with different design structures are contrasted and discussed. A comparison between the SGLS vacuum pump and CLS vacuum pump with the same pumping speed is presented at the end of this paper. 1 2014-A-1902 Formation of a nanophase wetting layer under non-equilibrium conditions and the growth of a transition metal on silicon Nikolay Plusnin1 1 Institute of Automation and Control Processes, Vladivostok, Russia The nanophase transition metal layer was found to wet a silicon substrate at a room substrate temperature and a low metal vapor temperature. As shown by Electron Energy Loss Spectroscopy data, this wetting is accomplished by adapting the metallic coating to the substrate. Atomic Force Microscopy data shows the nanophase topography of the coating, while IR and UV Optical Spectroscopy data show the metallization and nanostructuring the interface layer of the substrate. Auger Electron Spectroscopy data show the differences in the nanophase wetting layer from the bulk phases (metal and silicide) in electronic structure and composition. These differences are clearly manifested in the phase transition into these bulk phases with an increase in the thickness or the temperature of the coating. It is assumed that the adaptation itself occurs due to the formation of a nanophase or non-bulk cluster structure in the coating, as well as due to its reduced atomic density. In addition, it also occurs due to the nanostructuring of the interface layer of the substrate, which minimizes the energy of the system. It is discussed the application of given results for metal-semiconductor contact and for nanoplasmonics / nanospintronics. 1 2032-A-1902 Construction of inverse LEED states using results of repeated slab calculations Katsuyoshi Kobayashi1 1 Ochanomizu University Photoemission spectroscopy is a useful method for investigating electronic states of crystal surfaces. Photoemission is an excitation process of electrons by light from occupied states to unoccupied states above vacuum levels. In evaluating matrix elements of photoemission we need wave functions of unoccupied states satisfying correct boundary conditions, called inverse LEED states. We present a method of constructing inverse LEED states using results of repeated slab calculations. Inverse LEED states contain only out-going Bloch states in crystal regions. On the other hand, wave functions of repeated slab calculations contain both out-going and in-coming Bloch states. We present a method of constructing waves functions containing only out-going Bloch states using wave functions of repeated slab calculations. This method is applicable to the case of multiple Bloch states in crystal regions. We apply the present method to the Bi (111) surface, for which a spin and angle resolved photoemission spectroscopy (SARPES) experiment was performed (K. Yaji et al., Nat. Commun. 8, 14588 (2017)). Calculated results reproduce experimental results. The difference from the previous calculations imposing out-going boundary conditions in vacuum regions (K. Kobayashi, Phys. Rev. B 95, 205436 (2017)) is small. Repeated slab calculations are widely performed by density-functional methods using readily available simulation packages. Since the present method is simple and can make use of these packages, it extends the possibility of calculations of photoemission spectroscopy. 1 2039-A-1902 Reactions in cryogenic ice films. Enhanced dissociation of acids
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