Underpotential Codeposition of Fe–Pt Alloys from an Alkaline Complexing Electrolyte: Electrochemical Studies

Liang, Defu; Mallett, Jonathan J.; Zangari, Giovanni

doi:10.1149/1.3530786

Cited by 27 publications

(26 citation statements)

References 28 publications

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“…Similar effects have been observed in the UPCD of Pt-based alloys: acidic electrolytes where Pt is not complexed form porous films (Figure 3.25a) [96], while complexation of both Pt and Fe leads to dense, smooth, and shiny films, as detected by AFM imaging (Figure 3.25b) [113].…”

Section: Film Morphologysupporting

confidence: 71%

“…The example of Pt-Pb discussed in Section 3.4.2 exemplifies this behavior: the lattice constant of FCC Pt-Pb alloys is observed to gradually increase up to 40 at% Pb, suggesting solid solution formation; the bulk solubility of Pb in Pt however is negligible [101]. In addition, random solid solutions are often observed even in alloy systems that form ordered structures (such as in equiatomic Fe-Pt [112,113] or Co-Pt [114]) or intermetallic compounds (again, in Pt-Pb [101]). The metastable solid solution in these instances grows preferentially since the number of atomic configurations resulting in the competing ordered structure is much lower, leading to a statistical preference for the former.…”

Section: Crystallographic Structure and Microstructurementioning

confidence: 87%

“…Ordered structures present in the bulk phase diagram may be observed only after annealing at relatively high temperatures and in an inert atmosphere; the annealing temperature required to achieve full crystallization is lower if the initial film is dense and the concentration of impurities (oxygen, carbon, etc.) is low [113]. Figure 3.21 compares the thermal annealing and ordering process of equiatomic Fe-Pt films grown from acidic noncomplexing solutions [116] and from alkaline complexing electrolytes [113].…”

Section: Crystallographic Structure and Microstructurementioning

confidence: 99%

“…is low [113]. Figure 3.21 compares the thermal annealing and ordering process of equiatomic Fe-Pt films grown from acidic noncomplexing solutions [116] and from alkaline complexing electrolytes [113]. The former contain up to 30 at% oxygen and were observed to develop an ordered L1 0 tetragonal structure only after annealing in forming gas (5% H 2 in Ar) above 600 ∘ C. The latter incorporate a much lower oxygen fraction, and the L1 0 ordered phase can be obtained starting at temperatures as low as 400 ∘ C (Figure 3.21 or ZnO results in highly crystalline, and in some cases even single crystal, films, due to the high reversibility of the compound formation process; crystallinity is favored and crystallographic orientations are selected by the use of substrates favoring epitaxial growth [117] (Figure 3.22a).…”

Section: Crystallographic Structure and Microstructurementioning

confidence: 99%

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Electrochemical Surface Processes and Opportunities for Material Synthesis

Brankovic¹,

Zangari²

2015

Advances in Electrochemical Sciences and Engineering

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Technological advances in the operation and performance of microelectronic, optical, magnetic, and, more recently, energy conversion devices depend in large part on an ever-increasing accuracy of material synthesis and film fabrication methods. In particular, the ongoing miniaturization of devices requires strict control of the crystal structure and microstructure in film as well as patterned structures, often down to the atomic scale.Electrodeposition has an important role to play in this pursuit toward miniaturization and enhanced performance [1]. Underpotential deposition (UPD) [2, 3] and surface-limited redox replacement (SLRR) [4] exploit the low energy of the metal ion precursors in solution (of the order of the thermal energy, 0.025-0.03 eV) to control the formation or replacement of single atomic layers via self-limiting processes. In UPD, a monoatomic layer of metal M is deposited on a conductive substrate S at a potential more positive than the redox potential of M [2]. This shift in redox potential is made possible by the fact that the M-S bond is stronger than the M-M bond; since the effective pair interaction V eff = V MM + V SS − 2V MS is typically in the order of 0.01-0.1 eV, only low energy precursors are sensitive to these energy differences, thus limiting the deposit to one (or sometimes two) atomic layers. SLRR involves UPD monolayer formation, followed by displacement of this layer with a full or partial monolayer of a more noble element, through a cementation process [4]. An analogous process, selective electrodesorption-based atomic layer deposition (SEBALD) consists in the formation at UPD of a sacrificial sulfur monolayer to induce UPD of late transition metals such as Fe, Co, and Ni in the form of monolayers or nanosized islands [5].Underpotential codeposition (UPCD) is a generalization of the UPD process, whereby alloy electrodeposition occurs at potentials more positive than the redox potential of the less noble element [6]. UPCD is made possible by the effective atomic pair interactions in the solid state, or equivalently by the alloying bond enthalpy. In contrast with UPD, UPCD is used to form alloy films of arbitrary

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Section: Film Morphologysupporting

confidence: 71%

Section: Crystallographic Structure and Microstructurementioning

confidence: 87%

Section: Crystallographic Structure and Microstructurementioning

confidence: 99%

Section: Crystallographic Structure and Microstructurementioning

confidence: 99%

See 2 more Smart Citations

Electrochemical Surface Processes and Opportunities for Material Synthesis

Brankovic¹,

Zangari²

2015

Advances in Electrochemical Sciences and Engineering

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“…UPCD of Pt with the transition metals Fe, Co, Ni however resulted in codeposition only under diffusion limiting conditions for Pt, resulting in hydrogen evolution, pH increase at the interface, and oxygen incorporation in the films [54]. This problem was overcome by utilizing a Pt complex to shift the onset of Pt deposition more negative, leading to closer onset potentials for Fe and Pt and mostly avoiding oxygen incorporation [56,57]; the improved purity also resulted in an earlier onset of the phase transformation of FCC Fe-Pt to the high anisotropy tetragonal structure of interest in magnetic recording [58].…”

Section: Interactions In the Solidmentioning

confidence: 99%

Electrodeposition of Alloys and Compounds in the Era of Microelectronics and Energy Conversion Technology

Zangari

2015

Coatings

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Electrochemical deposition methods are increasingly being applied to advanced technology applications, such as microelectronics and, most recently, to energy conversion. Due to the ever growing need for device miniaturization and enhanced performance, vastly improved control of the growth process is required, which in turn necessitates a better understanding of the fundamental phenomena involved. This overview describes the current status of and latest advances in electrodeposition science and technology. Electrochemical growth phenomena are discussed at the macroscopic and atomistic scale, while particular attention is devoted to alloy and compound formation, as well as surface-limited processes. Throughout, the contribution of Professor Foresti and her group to the understanding of electrochemical interfaces and electrodeposition, is highlighted.

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