The fcc-hcp phase transition in electrodeposited epitaxial cobalt films

Gaigher, H.L.; Berg, N.G. van der

doi:10.1016/0013-4686(76)85108-0

Cited by 27 publications

(16 citation statements)

References 16 publications

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“…Previous work indicates that electrodeposited Co is mostly fcc at low pH (less than 2 or 3) with progressively more hexagonal close-packed (hcp) Co occurring at higher pH values. 61,62 The lattice parameter of fcc Co is close to that for Cu (0.354 nm vs. 0.361 nm for Co and Cu, respectively), 54 so rings from the two fcc patterns would be indistinguishable here. Although the electrolyte pH was always 4, no hcp rings were observed for these films.…”

Section: Resultsmentioning

confidence: 89%

“…This ring was indexed as an hcp Co reflection, indicating that some hcp Co is present, as seen previously in the literature. 61,62 Due to overlap with lines from fcc Cu, the observed ring is the only one from Co hcp expected to be visible here in a Co-Cu alloy. Selected area diffraction patterns taken directly on the columns suggest that most of the columns are single crystal and fcc in structure with a (111) texture.…”

Section: Resultsmentioning

confidence: 90%

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Additive Effects during Pulsed Deposition of Cu-Co Nanostructures

Kelly

Bradley

Landolt

2000

J. Electrochem. Soc.

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Electrodeposited alloys showing useful magnetic properties have been the focus of much study due to their technological importance for data storage and retrieval. [1][2][3][4][5][6] Most investigators studied the effects of processing conditions, such as deposition rate, pH, temperature, and mixing conditions, particularly for the Ni-Fe system. [7][8][9] Recent work has examined the giant magnetoresistances (GMR) for various combinations of electrodeposited multilayered magnetic alloys, primarily for reading and sensor applications. 10-13 Besides these multilayered alloys, there are other types of magnetic composite materials that could be used to create interesting magnetic devices, for instance, "granular" materials (magnetic clusters embedded in a nonmagnetic matrix) and hybrid cluster/multilayer alloys. 14-18 Multilayered nanowires produced with templates have attracted much attention as well. [19][20][21] Pulsed electrodeposition is well suited to the production of multilayer alloys. 22,23 We discuss the possibility of extending this technique to create novel Cu/Co composite structures with an electrolyte similar to one recently considered in the literature 24 using no template or masking technique. The microstructural effects of pulse parameters and two additives in this electrolyte, saccharin and sodium dodecyl sulfate (SDS), are investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM); the current efficiency, surface roughness, and composition are measured also. Other studies of electrodeposited Cu-Co alloys are available, 10,11,13,17,[25][26][27] in one of which the effects of two leveling agents on the electrodeposits are discussed. 26 Practically, additives are of industrial interest since some have been shown to improve the properties of magnetic write-head materials that are increasingly subject to new performance requirements. 9,24,28-30 A fundamental interest exists as well, since little is known about how additives effect changes in these material properties. [31][32][33] Experimental Films for microstructural and compositional analysis were deposited using an inverted rotating disk electrode (RDE), described in detail elsewhere. 34,35 Substrates for subsequent microstructural analysis were 100 nm of (111) preferentially oriented Ag sputtered on the polished side of doped Si disks having Ti adhesion layers; more details on these substrates are available elsewhere. 36 For compositional analysis, bulk Ag (99.95%, Goodfellow, England) working electrodes (WEs) polished to a near mirror finish and ultrasonically cleaned with ethanol served as substrates. The WE exposed area was 0.50 cm 2 for both types of substrates. A Labview program controlled a Heka potentiostat (PG 390 Heka Elektronik GmbH, Germany) for pulsed deposition. A mercury/mercurous sulfate electrode (Radiometer, France) acted as the reference electrode, while a dimensionally stable anode (Eltech Systems Corp.) served as the counter electrode. The rotation speed for all experiments was 1000 rpm. Depo...

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Section: Resultsmentioning

confidence: 89%

Section: Resultsmentioning

confidence: 90%

Additive Effects during Pulsed Deposition of Cu-Co Nanostructures

Kelly

Bradley

Landolt

2000

J. Electrochem. Soc.

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“…It is well known that elemental cobalt (Co) has an allotropic phase transformation in bulk form from the hexagonal-close-packed (hcp) phase to the face-centred-cubic (fcc) phase, fcc # cooling heating hcp, at 417 1C [1]. This heat induced phase transformation has been carefully studied by a number of techniques including X-ray diffraction (XRD) [1], electron diffraction [2], acoustic measurements [3], by theoretical calculations [4], and solid-state NMR [5]. It has been shown by Kitakami et al [6] that although at room temperature bulk Co should be hcp, there is a close relationship between the Co crystallite size and the crystal phase.…”

Section: Introductionmentioning

confidence: 99%

A 59Co NMR study to observe the effects of ball milling on small ferromagnetic cobalt particles

Speight

Wong

Ellis

et al. 2009

Solid State Nuclear Magnetic Resonance

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“…It is well-established that the structure of electrodeposited Co films ͑preference for fcc or hcp stacking as well as the amount of stacking faults͒ depends sensitively on the electrolytic parameters, such as overpotential and pH of the electrolyte used. 5,6 However, the theoretical explanation of the preference for a particular stacking order is not yet satisfactory, partly because those early studies were based mainly on the TEM observations, which do not give reliable quantitative information on the content of the respective phases. Such information can be provided by 59 Co NMR experiments, which give a distribution of hyperfine fields on Co nuclei in the entire sample volume.…”

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confidence: 99%

Structural study of nanometric electrodeposited Co films using Co59 NMR

Cerisier

Attenborough

Jędryka

et al. 2001

Journal of Applied Physics

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A Co59 NMR experiment has been used to investigate the structure of two series of Co films with thicknesses varying from 5 to 400 nm which were electrodeposited on Cu at the electrolyte pH value of 2.1 and 3.7, respectively. It was shown that the overall structure of studied Co films consists of a very good quality fcc phase and a heavily faulted hcp phase in about equal proportions. The exceptions are very thin Co layers (below 20 nm) where the hcp structure was stabilized at pH 3.7 and overpotential of 0.9 V. This effect is attributed to the formation of hexagonal cobalt hydroxide in the early stage of deposition, which acts as a buffer layer stabilizing Co hcp structure.

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The fcc-hcp phase transition in electrodeposited epitaxial cobalt films

Cited by 27 publications

References 16 publications

Additive Effects during Pulsed Deposition of Cu-Co Nanostructures

Additive Effects during Pulsed Deposition of Cu-Co Nanostructures

A 59Co NMR study to observe the effects of ball milling on small ferromagnetic cobalt particles

Structural study of nanometric electrodeposited Co films using Co59 NMR

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