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[en] Cantilever testing is an underutilized test method from which results and interpretations promote greater understanding of the tensile and shear failure responses of interconnects, metallizations, or bonded joints. The use and analysis of this method were pursued through the mechanical testing of sintered-silver interconnects that joined Ni/Au-plated copper pillars or Ti/Ni/Ag-plated silicon pillars to Ag-plated direct bonded copper substrates. Sintered-silver was chosen as the interconnect test medium because of its high electrical and thermal conductivities and high-temperature capability—attractive characteristics for a candidate interconnect in power electronic components and other devices. Deep beam theory was used to improve upon the estimations of the tensile and shear stresses calculated from classical beam theory. The failure stresses of the sintered-silver interconnects were observed to be dependent on test-condition and test-material-system. In conclusion, the experimental simplicity of cantilever testing, and the ability to analytically calculate tensile and shear stresses at failure, result in it being an attractive mechanical test method to evaluate the failure response of interconnects.
[en] We report that the arrangement of the electrode materials is a significant contributor for constructing high performance supercapacitor. Here, vertically-aligned Mn(OH)2 nanosheet thin films were synthesized by cathodic electrodeposition technique on flexible Au coated polyethylene terephthalate substrates. Morphologies, microstructures, chemical compositions and valence state of the nanosheet films were characterized systematically. It shows that the nanosheets arranged vertically to the substrate, forming a porous nanowall structures and creating large open framework, which greatly facilitate the adsorption or diffusion of electrolyte ions for faradaic redox reaction. Electrochemical tests of the films show the specific capacitance as high as 240.2 F g-1 at 1.0 A g-1. The films were employed to assemble symmetric all-solid-state supercapacitors with LiCl/PVA gel severed as solid electrolyte. Finally, the solid devices exhibit high volumetric capacitance of 39.3 mF cm-3 at the current density 0.3 mA cm-3 with robust cycling stability. The superior performance is attributed to the vertically-aligned configuration.
[en] A novel self-supporting carbon thin film flexible supercapacitor electrode with high volumetric and areal capacitance was developed. The increase in capacitance performance is achieved by introducing channels across the carbon thin film using ion-track technology. In the first step of the electrode synthesis, latent tracks are inscribed in the starting polyimide (Kapton) foil by irradiation with 253 MeV Kr ions. Next, macropores in the form of cylindrical channels are formed by selective chemical etching with NaOCl along the ion tracks, creating ion-track polymer. With subsequent carbonization and activation of the ion-track polymer, activated ion-track carbon is produced. A range of samples are obtained by varying the chemical etching time of the irradiated polymer. In addition to channel formation the chemical etching time influences the composition of surface functional groups. The best results are obtained by chemical etching for 40 min, the thickness of the sample is 21 A mu m with channel density 2.4 x 10(6) cm(-2) and average channel diameter 430 nm. Beside cylindrical macro channels this material is mainly microporous with 0.62 nm pore diameter and shows the highest areal (494 mF/cm(2)), volumetric (224 F/cm(3)) and gravimetric (178 F/g) capacitance. As a consequence of channel formation, the rate capability of the supercapacitor was also increased.
[en] MgZnO is emerging as a vital semiconductor-alloy system with desirable optical properties that can span a large range of the UV spectrum. Due to its benign chemical character, MgZnO is considered to be an environmentally friendly material. This paper presents studies on annealing as a useful and straightforward approach for the enhancement of the optical and crystal quality of Mg 0.17Zn 0.83O nanocrystalline films grown via DC sputtering. The alloys were studied via several imaging and optical techniques. It was found that high-temperature annealing, ~900 °C, in Argon atmosphere, significantly improves the solubility of the alloy. This temperature range is consistent with the thermal diffusion temperature of Mg needed for the creation of a soluble alloy. Moreover, the annealing process was found to minimize the undesirable visible luminescence, attributed to Mg and Zn interstitials, while significantly enhancing the bandgap sharpness and the efficiency of the UV-luminescence at ~3.5 eV. The analysis indicated that these optical attributes were achieved due to the combined effects of good solubility, an improved morphology, and a reduction of native defects. The annealing was also proven to be beneficial for the reduction of the compressive stress in the alloy: a relaxation ~1.8 GPa was calculated viamore » Raman scattering. The inherent stress was inferred to originate mainly from the granular morphology of the alloys.
[en] Ion-beam mixing at Ti-Si interfaces induced by krypton ions has been studied as a function of fluence and temperature by means of sheet resistivity measurements and a 2 MeV 4He+ Rutherford backscattering spectrometry. For mixing induced by 200 keV Kr+, substrate temperatures during irradiation between 30 and 4000C and with fluences ranging from 1.0 x 1015 to 7.5 x 1015 Kr+/cm2, the amount of mixing has a linear fluence dependence at low fluences and square-root fluence dependence at high fluences. Above ∼ 1000C, the mixing is strongly temperature dependent. The activation energy for the temperature-dependent part is ∼ 0.115 eV. Also, 300 keV Kr+ ion mixing at room temperature with fluences ranging from 2.5 x 1016 to 1.0 x 1017 Kr+/cm2 displays a linear fluence dependence in this fluence range and the formation of nonuniform TixSi1-x layers. (author)
[en] A review is given of the various aspects of solar-cell degradation in space. By way of introduction, defect creation in a solid by energetic particles is outlined, and the basic results of solar-cell theory are presented. The identification of the minority-carrier lifetime as the principal quantity of concern in solar-cell degradation then paves the way for the discussion of specific materials. The radiation damage in silicon, gallium arsenide and indium phosphide solar cells is discussed in some detail, paying particular attention to microscopic defects and their interaction with impurities. (author)
[en] The article titled “Strontium-substituted La0.75Ba0.25−xSrxFeO3 (x = 0.05, 0.10 and 0.15) perovskite: dielectric and electrical studies”, written by F. B. Abdallah, A. Benali, S. Azizi, M. Triki, E. Dhahri, M. P. F. Graça, M. A. Valente, was originally published electronically on the publisher's internet portal (currently SpringerLink) on March 2019 with open access.
[en] The original version of this article unfortunately contains errors in Abstract, Section 4.4 Vickers microhardness test and Section 5 Conclusion. In Abstract (7th line) the word “hard” should be changed to “soft”, in Section 4.4 Vickers microhardness test, 15th line the value 1.04 should be changed to 3.27 and in the same sentence the word “hard” should be changed to “soft”. In Section 5 Conclusion (18th line) the word “hard” should be changed to “soft”.