1,721,055 research outputs found
Feedback control of morphology evolution in metal electrodeposition by optical means
No full textControl of morphology and in particular of roughness, is critical in metal electrodeposition. Morphology control is traditionally achieved by indirect chemical methods implying addition agents whose mechanisms of action are often rather poorly known, thus rendering the stability of processes questionable. In this paper we mean to tackle some basic problems paving the way to direct closed-loop control of morphology. The single components of a possible control loop are developed conceptually and implemented in actual devices and routines. Proper closed-loop operation of the system is on its way and will be reported in a subsequent paper. An optical method meant to directly quantify surface-roughness is devised. IR radiation scattering by reflecting surfaces is sensitive to roughness in the range typically relevant to electroplating. Reflected IR intensity at suitable frequencies is used to transduce in-situ time-dependent electrode roughness. Quantitative correlations are proposed and checked against samples of calibrated roughness both ex-situ and in-situ. A simple analytical model of roughness evolution during galvanostatic electroplating is proposed for control purposes. A suitable algorithm for automatic galvanostatic control is developed
Electrodeposition of copper from triethanolamine as a complexing agent in alkaline solution
Full text linkThe use of triethanolamine (TEA) as a cyanide-free electrolyte for copper electrodeposition was studied. The effect of TEA concentration on electrodeposition rate and cathodic adsorption during 3D copper growth was investigated. Linear sweep voltammetry (LSV), electrochemical quartz crystal microbalance (EQCM), scanning electron microscope (SEM), chronoamperometry and in situ surface-enhanced Raman scattering (SERS) were used to achieve a kinetic, thermodynamic, and mechanistic understanding. TEA forms stable complexes with copper, the most stable being Cu(TEA)(OH)3?. Also, it acts as a surface modifier, promoting instantaneous nucleation and lower reduction rates to metallic copper. Thus, three-dimensional growth is controlled and, consequently, a smooth and homogeneous copper deposit is achieved
"Electrodeposition And Structural Characterisation Of Au-Sn Alloys" Articolo accettato per: ,
No full textX-ray absorption spectromicroscopy gives access to Li1+xAlxGe2−x(PO4)3 (LAGP) local degradation at the anode-electrolyte interface
Full text linkBatteries with inorganic solid-state electrolytes (ISSE) are attracting notable interest for next-generation systems implementing Lithium (Li) metal anodes, in view of achieving higher energy densities combined with superior safety. Notwithstanding extensive research and development work, this technology is not yet ready for industrial implementation, one of the key challenges being the stability of ISSEs, chiefly at the anodic interface. This work attacks this issue for the specific case of the LAGP/Li (Lithium Aluminium Germanium Phosphate/Lithium) interface with a micro-spectroscopic approach centred on post mortem Scanning Transmission X-ray Microscopy (STXM) of intact LMO/LAGP/Li thin-film batteries, microfabricated in discharged state. Pristine and cycled cells were mapped to pinpoint morphochemical changes, induced by electrochemical ageing. The evidenced shape changes, corresponding to mechanical damaging of the solid/solid electrodic interfaces correlate with LAGP decomposition at the anode, leading to reduction of Ge, whereas the chemical state at the cathodic interface is preserved. Thanks to its submicron spacial resolution, the STXM at the Ge L-edge and O K-edge spectra allowed to assess the highly localized nature of the chemical transformation of LAGP and its correlation with the for-mation of Li outgrowth features
In situ Surface Enhanced Raman and Electroreflectance Spectroelectrochemical Investigations of Organic Additives during the Electrodeposition of Cu from Acidic sulphate Solutions
No full textElectrochemical fabrication of nano- and micrometric Cu particles: in situ investigation by electroreflectance and optical second harmonic generation
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