Electrochemical Deposition of FeSe on RABiTS Tapes

Abstract

FeSe film is successfully fabricated onto rolling assisted biaxially textured substrate (RABiTS) tapes by an electrochemical deposition technique. The deposited FeSe films tend to become high crystallinity with a decrease in the applied voltage to -1.0 V, and the compositional ratio of Fe to Se approaches 1:1. The sample deposited at -1.0 V shows a superconducting transition at approximately 8.0 K in the magnetic susceptibility. 3After the discovery of superconductivity in iron-based compounds [1], much attention has been paid to the development of superconducting applications under a high magnetic field [2], because of their high upper critical and irreversibility fields [3]. The iron chalcogenides FeSe are one of the members of iron-based superconductors with the simplest structure among them. The original transition temperature T c of 8 K [4] increases above 30 -46 K by the intercalation of alkali or alkaline earth elements [5][6][7][8][9][10]; it also increases to 37 K under high pressure [11][12][13][14]. The large increase in T c is attributed to the sensitivity in its local structural difference such as the anion height from Fe atoms [15]. This is related to the relatively higher T c of FeSe tapes or thin films than that of bulk FeSe because of its lattice strain [16][17][18]. These facts indicate that FeSe is a potential material for superconducting wires or tapes. It is important for industrial applications to develop simple and low-cost methods of fabricating thin films over large areas.We have been developing the deposition of FeSe by the electrochemical technique.Superconducting FeSe films were deposited onto an Fe substrate by this method [19,20]. This is the first case of the preparing tape-shaped superconducting materials by an electrochemical method. If we can change the substrate to other metals, it would lead to a wide variety of the fabrication processes.In this study, we chose the rolling assisted biaxially textured substrates (RABiTS) tape as a 4 substrate, and performed an electrochemical deposition of FeSe onto the tape. The deposited FeSe shows superconductivity at approximately 8.0 K, comparable to the T c of bulk materials. This is part of the studies to develop fabricating conditions for FeSe as a thin film by an electrochemical technique.The electrochemical depositions were performed for 30 min at a constant voltage by a three-electrode method. A platinum plate, a RABiTS tape (evico GmbH), and a Ag/AgCl electrode were used as an anode, a cathode, and a reference electrode, respectively. The RABiTS tape is composed of (001)-plane-oriented Ni formed by the recrystallization of cold-rolled pure Ni. A mixture of 0.03 mol/l FeCl 2 ·4H 2 O, 0.015 mol/l SeO 2 , and 0.1 mol/l Na 2 SO 4 was dissolved in distilled water for the preparation of the electrolyte. The pH of the electrolyte was adjusted to 2.1 by adding H 2 SO 4 . Powder X-ray diffraction (XRD) measurements were carried out using Mini Flex 600 (RIGAKU) with Cu-K radiation. The compositional ratio was analyzed by energy dispe...

Thickness dependence of structural and superconducting properties of Co-doped BaFe2As2 coated conductors

“…Iron-based superconductors (IBSs), exhibiting high upper critical fields ( H c2 ), larger critical grain boundary angle ( θ c ), small anisotropies ( γ ), and robust superconductivity to disorder, demonstrate an excellent potential for high-field applications ( Hosono et al., 2018 ; Sakoda et al., 2018 ; Iida et al., 2020 ). Coated conductor (CC) templates, which have been developed with tremendous success in cuprate-based superconductors, are also favorable for growth of IBS epitaxial films, such as Ba122 (Ba(Fe 1-x Co x ) 2 As 2 and BaFe 2 (As 1-x P x ) 2 ) ( Iida et al., 2011b , 2017 ; Hiramatsu et al., 2017 ; Sato et al., 2016 ; Trommler et al., 2012a , 2012b ; Katase et al., 2011 ; Xu et al., 2018 ) and 11 thin films (FeSe x Te 1−x ) ( Sylva et al., 2019 ; Nabeshima et al., 2017 ; Demura et al., 2016 ; Si et al., 2011 , 2013 ; Yuan et al., 2015 ). In particular, the P-doped Ba122 CCs on the ion beam-assisted deposition (IBAD)-MgO buffered metal tapes show values of critical current densities ( J c ) over 0.1 MA/cm 2 at 15 T ( Iida et al., 2017 ), indicating their excellent potential for high-field applications.…”

Electrochemical Synthesis of Iron Monoselenide Thin Films

“…In some studies, FeSe thin films were deposited on a conductive glass electrode coated with fluorine-additive tin oxide by electronbeam evaporation of Fe(NO 3 )•9H 2 O in the range of 0.18-0.03M concentration. The effect of concentration on the thickness, structure, surface morphology, composition and optical properties of deposited samples were studied [7][8][9][10][11][12]. Nanocrystalline iron monoselenide was synthesized on the surface of platinum or gold electrodes from aqueous acid solutions containing HSeO 3 -, SeO 3 2-and Fe 2+ ions by potentiostatic or galvanostatic methods.…”

Observation of zero resistance in as-electrodeposited FeSe

“…As a new way to synthesize FeSe superconductors, we have developed an electrochemical deposition technique [8][9][10][11], which can be deposited on various substrates by applying voltage to the substrates in the solution. This suggests the possible fabrication of FeSe superconducting tape by a reel-to-reel method: immersing a conducting tape into a solution and applying voltage.…”