Erratum: “Seed layer technique for high quality epitaxial manganite films” [AIP Advances 6, 085109 (2016)]

No abstract available

Surface nanostructures in manganite films

Ultrathin manganite films are widely used as active electrodes in organic spintronic devices. In this study, a scanning tunnelling microscopy (STM) investigation with atomic resolution revealed previously unknown surface features consisting of small non-stoichiometric islands. Based upon this evidence, a new mechanism for the growth of these complex materials is proposed. It is suggested that the non-stoichiometric islands result from nucleation centres that are below the critical threshold size required for stoichiometric crystalline growth. These islands represent a kinetic intermediate of single-layer growth regardless of the film thickness, and should be considered and possibly controlled in manganite thin-film applications

Vega: A Ten-Core SoC for IoT Endnodes with DNN Acceleration and Cognitive Wake-Up from MRAM-Based State-Retentive Sleep Mode

The Internet-of-Things (IoT) requires endnodes with ultra-low-power always-on capability for a long battery lifetime, as well as high performance, energy efficiency, and extreme flexibility to deal with complex and fast-evolving near-sensor analytics algorithms (NSAAs). We present Vega, an IoT endnode system on chip (SoC) capable of scaling from a 1.7- μW fully retentive cognitive sleep mode up to 32.2-GOPS (at 49.4 mW) peak performance on NSAAs, including mobile deep neural network (DNN) inference, exploiting 1.6 MB of state-retentive SRAM, and 4 MB of non-volatile magnetoresistive random access memory (MRAM). To meet the performance and flexibility requirements of NSAAs, the SoC features ten RISC-V cores: one core for SoC and IO management and a nine-core cluster supporting multi-precision single instruction multiple data (SIMD) integer and floating-point (FP) computation. Vega achieves the state-of-the-art (SoA)-leading efficiency of 615 GOPS/W on 8-bit INT computation (boosted to 1.3 TOPS/W for 8-bit DNN inference with hardware acceleration). On FP computation, it achieves the SoA-leading efficiency of 79 and 129 GFLOPS/W on 32- and 16-bit FP, respectively. Two programmable machine learning (ML) accelerators boost energy efficiency in cognitive sleep and active states

Recycling graphene from supercapacitor electrodes as reinforcing filler for epoxy resins

A wet shredding process has been developed for recycling graphene from the electrodes of supercapacitors into polymer composites. At first, supercapacitors are cut open to expose the interior graphene based electrodes. The electrodes are heat-treated at 200o C to remove the contained solvent, and the heat treatment temperature can be further increased to remove the polymer binder, which binds the graphene on an aluminium foil current collector. After heat treatment, the electrodes are shredded in an epoxy resin to strip off the graphene and the graphene was subsequently dispersed using a high shear mixer. The dispersed graphene is used directly as reinforcing filler for the epoxy resin. A content of 0.40% (wt) of the recycled graphene resulted in a significant increase in both the tensile strength and elongation at break of the epoxy resin. Removal of the binder increases the reinforcing effect of the recycled graphene. However, a compromise can be made to leave the binder in the recycled graphene in order to avoid secondary pollution

Nucleant layer effect on nanocolumnar ZnO films grown by electrodeposition

Different ZnO nanostructured films were electrochemically grown, using an aqueous solution based on ZnCl2, on three types of transparent conductive oxides grow on commercial ITO (In2O3:Sn)-covered glass substrates: (1) ZnO prepared by spin coating, (2) ZnO prepared by direct current magnetron sputtering, and (3) commercial ITO-covered glass substrates. Although thin, these primary oxide layers play an important role on the properties of the nanostructured films grown on top of them. Additionally, these primary oxide layers prevent direct hole combination when used in optoelectronic devices. Structural and optical characterizations were carried out by scanning electron microscopy, atomic force microscopy, and optical transmission spectroscopy. We show that the properties of the ZnO nanostructured films depend strongly on the type of primary oxide-covered substrate used. Previous studies on different electrodeposition methods for nucleation and growth are considered in the final discussion.We thank Prof. A. Segura of the Universitat de Valencia for the facilities with the sputtering equipment. This work was supported by the project PROMETEO/2009/074 from the Generalitat Valenciana.Reyes Tolosa, MD.; Damonte, LC.; Brine, H.; Bolink, HJ.; Hernández Fenollosa, MDLÁ. (2013). Nucleant layer effect on nanocolumnar ZnO films grown by electrodeposition. Nanoscale Research Letters. 8:135-144. https://doi.org/10.1186/1556-276X-8-135S1351448Franklin JB, Zou B, Petrov P, McComb DW, Ryanand MP, McLachlan MA,J: Optimised pulsed laser deposition of ZnO thin films on transparent conducting substrates. Mater Chem 2011, 21: 8178–8182. 10.1039/c1jm10658aJaroslav B, Andrej V, Marie N, Šuttab P, Miroslav M, František U: Cryogenic pulsed laser deposition of ZnO. 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J Electrochem Soc 2012, 159: E45-E51. 10.1149/2.093202jesPruna A, Pullini D, Busquets Mataix D: Influence of deposition potential on structure of ZnO nanowires synthesized in track-etched membranes. J Electrochem Soc 2012, 159: E92-E98. 10.1149/2.003205jesMarotti RE, Giorgi P, Machado G, Dalchiele EA: Crystallite size dependence of band gap energy for electrodeposited ZnO grown at different temperatures. Solar Energy Materials and Solar Cells 2009, 90(15):2356–2361.Yeong Hwan K, Myung Sub K, Jae Su Y: Structural and optical properties of ZnO nanorods by electrochemical growth using multi-walled carbon nanotube-composed seed layers. Nanoscale Res Lett 2012, 7: 13. 10.1186/1556-276X-7-13Elias J, Tena-Zaera R, Lévy-Clément C: Electrodeposition of ZnO nanowires with controlled dimensions for photovoltaic applications: role of buffer layer. 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On the surface integrity of additive manufactured and post-processed AlSi10Mg parts

The research centres on the evaluation of surface integrity of AlSi10Mg parts produced via laser-based powder bed fusion (LPBF) process, followed by vibratory surface finishing. The alloy is chosen for its applications in lightweight components used in electronic packaging, automotive and aerospace sectors. Initial experiments involve optimisation of key LPBF process parameters by analysing the surface roughness and density data of the built parts. A Taguchi L18 orthogonal array is used for the optmisation trials with variations in the laser power (P), beam scanning speed (v), hatch spacing (H) and island size (I). Latter experimental phase deals with microhardness and microstructure assessment of heat treated LPBF specimens that are produced using the optimised LPBF parameters, i.e. P: 250 W, v: 1500 mm/s, H: 75 µm and I: 2 mm. Microhardnesses of the annealed samples reduce by ~12% with respect to the as-built parts and the values remain almost unchanged from the annealed state following solution treatment and ageing. The fish-scale like melt-pools observed on the unheat treated samples begin to fade off in the annealed specimens and completely disappear after solution treatment and ageing, with silicon particles dispersed all over the aluminium matrix. The final experimental phase involves vibratory surface finishing of the as-built LPBF parts using a vibrating ceramic media mixed with different acid and amine based liquid compounds for 1-6 hours, followed by vibrating in a maize based media for another 1-6 hours. The process aids in reducing the parts’ roughness, Sa by ~35-70%, however the effect is more prominent when using the ceramic media