Author, as appears in the article.: Mozalev, Alexander; Bendova, Maria; Gispert-Guirado, Francesc; Llobet, Eduard; Habazaki, Hiroki
Department: Enginyeria Electrònica, Elèctrica i Automàtica
URV's Author/s: Gispert Guirado, Francesc / GUIRADO PAGÉS, FRANCISCO / Llobet Valero, Eduard
Keywords: 3d nanostructures Anodic oxide films Anodization Arrays Electrical-properties Electrolytic capacito Electrolytic capacitor Fabrication Growth Layers Niobium Oxide-films Porous anodic alumina Refinemen Tantalum Tantalum-niobium alloy Tantalum‑niobium alloy
Abstract: The Ta-52 at.%Nb thin alloy films were magnetron sputter-deposited over a low-aspect-ratio nanoporous anodic-alumina template formed in 0.05 M tartaric acid solution at 250 V and modified by the pore-widening technique to enlarge the pores up to similar to 500 nm. The alloy coated the pores evenly, thus forming a 3D continuous conducting nanofilm on the template. Partially anodizing the templated alloy in a borate buffer solution of pH 7.5 generated a compact amorphous mixed-oxide anodic film thickening proportionally to the applied voltage. It was revealed that the oxide on the Ta-52 at.%Nb alloy grows with a slower migration of Ta5+ ions relative to Nb5+ ions, resulting in mixing Ta2O5 and Nb2O5 in the film depth and forming a few-nm-thick Nb2O5 outmost layer. The unique migration of Ta4+, Ta3+, Nb4+, and Nb3+ ions is assumed accountable for forming corresponding suboxides in the 3D anodic film in contrast to a flat Ta-52 at.%Nb alloy film used as a reference. The 3D anodic films behave as an n-type semiconductor with a low donor density N-d = similar to 2 x 10(18) cm(-3), appropriate for dielectric applications. An unusual two-layered structure with a sharp electrical interface revealed in the 3D oxide films anodized to 30-130 V, comprising a low-resistivity layer superimposed on the high-resistivity layer, is explained by an immobile negative space charge in the outer film part. The air-annealing at moderate temperatures releases the space charge and transforms the two layers into a high-resistivity single layer having substantially improved dielectric properties and thermostable (up to 250 degree celsius) capacitance of 1.2 mu F cm(-2) achieved for the film anodized to practical 50 V. The 3D films having up to 4.5 times enlarged effective surface area can be utilized as novel metal/oxide nanostructured electrodes for electrolytic microcapacitors suitable for classical electronic circuits and energy-storage applications.
Thematic Areas: Astronomia / física Biotecnología Chemistry (all) Chemistry (miscellaneous) Ciências agrárias i Ciências biológicas i Ciências biológicas ii Condensed matter physics Engenharias i Engenharias ii Engenharias iii Engenharias iv Ensino Farmacia General chemistry Geociências Interdisciplinar Materiais Materials chemistry Materials science, coatings & films Medicina ii Odontología Physics, applied Química Saúde coletiva Surfaces and interfaces Surfaces, coatings and films
licence for use: https://creativecommons.org/licenses/by/3.0/es/
Author's mail: eduard.llobet@urv.cat
Author identifier: 0000-0001-6164-4342
Record's date: 2024-10-19
Papper version: info:eu-repo/semantics/publishedVersion
Papper original source: Surface & Coatings Technology. 489 131042-
APA: Mozalev, Alexander; Bendova, Maria; Gispert-Guirado, Francesc; Llobet, Eduard; Habazaki, Hiroki (2024). Porous-anodic-alumina-templated Ta-Nb-alloy/oxide coatings via the magnetron-sputtering/anodizing as novel 3D nanostructured electrodes for energy-storage applications. Surface & Coatings Technology, 489(), 131042-. DOI: 10.1016/j.surfcoat.2024.131042
Licence document URL: https://repositori.urv.cat/ca/proteccio-de-dades/
Entity: Universitat Rovira i Virgili
Journal publication year: 2024
Publication Type: Journal Publications
Repositori URV