Optimization of mixed conductivity through nanostructure control in WO3 thin films

Samad, B. Abdel; Ashrit, P. V.

doi:10.1016/j.tsf.2017.07.025

Cited by 5 publications

(1 citation statement)

References 16 publications

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“…Notably, these peaks were sharper and more pronounced for the latter than for the former films, which implied that films deposited at 180 W exhibited a more porous texture, higher crystallinity, and rougher surface. [26][27][28] In addition, it has been well recognized that the surface structure of electrodes directs electron transfer (ET) reactions in electrochemistry and specific surface structures can drive the ET faster. 29,30) The reaction conducted at the electrodes is also sensitive to the surface structure.…”

Section: Resultsmentioning

confidence: 99%

Evaluation of lithium cobalt oxide films deposited by radio frequency magnetron sputtering as thin-film battery cathodes

Jan¹,

Lee²,

Yu³

et al. 2019

Jpn. J. Appl. Phys.

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Herein, we describe the fabrication of LiCoO2 thin films by high-frequency (27.12 MHz) magnetron sputtering and investigate the effects of sputtering power and Ar/O2 ratio on their morphological and electrochemical properties. Films produced at higher sputtering powers and O2 proportions are shown to exhibit increased porosity and a greater number of surface active sites. The discharge capacity of the film prepared at a sputtering power of 180 W and an Ar/O2 ratio of 1/2 is determined as 22.894 μAh μm–1 cm–2 using half-cell electrochemical testing at 0.2 C for 20 charge–discharge cycles, and ∼90% of the 0.2 C discharge capacity is retained at 1.5 C. Finally, we compare films deposited at 27.12 MHz with those deposited at 13.56 MHz, showing that the former feature the advantages of higher deposition rate and increased surface porosity, which results in excellent electrochemical performance and good rate capability.

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Section: Resultsmentioning

confidence: 99%

Evaluation of lithium cobalt oxide films deposited by radio frequency magnetron sputtering as thin-film battery cathodes

Jan¹,

Lee²,

Yu³

et al. 2019

Jpn. J. Appl. Phys.

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Amorphous WO3- thin films with color characteristics tuned by the oxygen vacancies created during reactive DC sputtering

Guillén

Herrero

2021

Journal of Materials Science & Technology

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Thermomechanical properties of amorphous metallic tungsten-oxygen and tungsten-oxide coatings

et al. 2019

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Metallic amorphous tungsten-oxygen and amorphous tungsten-oxide films, deposited by Pulsed Laser Deposition, are characterized. The correlation is investigated between morphology, composition, and structure, measured by various techniques, and the mechanical properties, characterized by Brillouin Spectroscopy and the substrate curvature method. The stiffness of the films is correlated to the oxygen content and the mass density. The elastic moduli decrease as the mass density decreases and the oxygen-tungsten ratio increases. A plateau region is observed around the transition between the metal-like (conductive and opaque) films and the oxide ones (non conductive and transparent). The compressive residual stresses, moderate stiffness and high local ductility of compact amorphous tungsten-oxide films are interesting for applications involving thermal or mechanical loads. The coefficient of thermal expansion is quite high (8.9 · 10 −6 K −1 ), being strictly correlated to the amorphous structure and stoichiometry of the films. Upon thermal treatments the coatings show a quite low relaxation temperature of 450 K. Starting from 670 K, they crystallize into the γ monoclinic phase of WO 3 , the stiffness increasing by about 70%. The measured thermomechanical properties provide a guidance for the design of devices which include a tungsten based layer, in order to assure their mechanical integrity. mitigating or favoring crack formation. Similarly, in high temperature applications, a significant mismatch between the coefficients of thermal expansion of the coating and of the substrate can induce high interface stresses, with possible coating delamination and device failure. More specifically, in an electrochromic system the W oxide film is part of a complex multilayer system: it is deposited on a transparent conductor, like ITO, and faces the electrolyte, solid or liquid, containing the ions responsible of the electrochromic effect, and can be subject to various and very different stress states [15]. Moreover, in some applications (e.g. solar-cells, thermophotovoltaic) tungsten oxide coatings operate at temperatures above room temperature [16]; this could induce phase transition or recrystallization, with a consequent variation of the as-deposited properties. Although the thermomechanical properties of tungsten based coatings can be crucial for the design of devices which exploit them, relatively fewer studies have investigated the relationship between their nanostructure, composition and mechanical properties [17,18,19]. The goal of this work is to achieve a more comprehensive understanding of the effects of structure, morphology and chemical composition on the thermomechanical properties of different systems of amorphous W-O and WO x coatings, providing useful results for the design of devices. We investigate amorphous films characterized by different oxygen/tungsten ratios and morphologies. To produce them we selected the Pulsed Laser Deposition (PLD) technique, which allows a significant versatility in tailoring the str...

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Optimization of mixed conductivity through nanostructure control in WO3 thin films

Cited by 5 publications

References 16 publications

Evaluation of lithium cobalt oxide films deposited by radio frequency magnetron sputtering as thin-film battery cathodes

Evaluation of lithium cobalt oxide films deposited by radio frequency magnetron sputtering as thin-film battery cathodes

Amorphous WO3- thin films with color characteristics tuned by the oxygen vacancies created during reactive DC sputtering

Thermomechanical properties of amorphous metallic tungsten-oxygen and tungsten-oxide coatings

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