DSpace university logo mark
Advanced Search
Japanese | English 

NAOSITE : Nagasaki University's Academic Output SITE > Faculty of Engineering > Articles in academic journal >

Determination of Crystal Growth Geometry Factors and Nucleation Site Densities of Electrodeposited Ferromagnetic Cobalt Nanowire Arrays


File Description SizeFormat
Crystals9_142.pdf7.11 MBAdobe PDFView/Open

Title: Determination of Crystal Growth Geometry Factors and Nucleation Site Densities of Electrodeposited Ferromagnetic Cobalt Nanowire Arrays
Authors: Saeki, Ryusei / Ohgai, Takeshi
Issue Date: 10-Mar-2019
Publisher: MDPI AG
Citation: Crystals, 9(3), art.no.142; 2019
Abstract: The time-dependence of electrochemical reduction current, which was observed during the one-dimensional (1-D) crystal growth of ferromagnetic cobalt nanowire arrays, was analyzed by Johnson–Mehl–Avrami–Kolmogorov (JMAK) theory. Textured hcp-Co nanowire arrays were synthesized by potentio-static electrochemical reduction of Co 2+ ions in anodized aluminum oxide (AAO) nanochannel films. Crystal growth geometry factor n in the JMAK equation was determined to be ca. 1. Hence, the electrochemical crystal growth process of a numerical nanowires array can be explained by 1-D geometry. The crystal nucleation frequency factor, k in JMAK equation was estimated to be the range between 10 −4 and 10 −3 . Our experimental results revealed that the crystal nucleation site density N d increased up to 2.7 × 10 −8 nm −3 when increasing the overpotential for cobalt electrodeposition by shifting the cathode potential down to −0.85 V vs. Ag/AgCl. The (002) crystal orientation of hcp-Co nanowire arrays was, remarkably, observed by decreasing N d . Spontaneous magnetization behavior was observed in the axial direction of nanowires. By decreasing the overpotential for cobalt electrodeposition, the coercivity of the nanocomposite film increased and reached up to 1.88 kOe, with a squareness of ca. 0.9 at room temperature.
Keywords: Johnson–Mehl–Avrami–Kolmogorov (JMAK) theory / electrodeposition / cobalt / nanowire array / crystal growth geometry / nucleation site density / crystal orientation / uniaxial magnetization
URI: http://hdl.handle.net/10069/39183
DOI: 10.3390/cryst9030142
Rights: © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Type: Journal Article
Text Version: publisher
Appears in Collections:Articles in academic journal

Citable URI : http://hdl.handle.net/10069/39183

All items in NAOSITE are protected by copyright, with all rights reserved.

 

Valid XHTML 1.0! Copyright © 2006-2015 Nagasaki University Library - Feedback Powerd by DSpace