Direct Observations of Inclusions in Electrodeposited Films by Transmission Electron Microscopy

Nakahara, S.

doi:10.1149/1.2124049

Cited by 15 publications

(10 citation statements)

References 8 publications

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“…The number density of incorporated additive molecules n incorp is estimated as [5] where N A is Avogadro's number. Table III, taken partially from Nakahara, 35 shows previous studies of additive incorporation. These observed particles were most probably clusters of molecules.…”

Section: Discussionmentioning

confidence: 99%

Electrochemical Quartz Crystal Microbalance Study of Additive Effects in Pulsed Deposition of Cu-Co Alloys

Kelly

Kern

Landolt

2000

J. Electrochem. Soc.

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Additives have strong effects on the physical properties of electrodeposited alloys that are used in data storage applications. 1 The electrochemical quartz crystal microbalance (EQCM) has been employed to study the effect of additives during electrodeposition, 2,3 corrosion, 4,5 and battery electrode processes. 6 Buttry and Ward reviewed the technique thoroughly. 7 Pulse-plating applications of the EQCM have principally focused on internal stress measurements in multilayered alloys exhibiting giant magnetoresistance. 8,9 Since electrolytes used in producing such multilayered alloys contain the more noble metal ion usually in small concentration, 10 well-defined hydrodynamics are important for electrochemical investigations of these systems.In a previous study, the additives saccharin and sodium dodecyl sulfate (SDS, also known as sodium lauryl sulfate) had a significant effect upon the composition, morphology, and microstructure of pulse-plated Cu-Co alloys. 11 In this study, a rotating EQCM 12 (r-EQCM) is used for the first time to study how additives affect fundamental deposition and corrosion processes that govern the composition and morphology of pulse-plated alloys under controlled hydrodynamic conditions. The r-EQCM is particularly well-suited for this problem, since it allows one to monitor deposition rates in situ for the pulse on-and off-times separately with well-defined fluid flow. Pulse-plating studies of alloys employing additives are available (Ref. 13-15 and references therein), but relatively few of them deal specifically with the transient behavior during pulsed deposition. 16,17 This problem is of practical interest however, since pulse-plating with additives could prove especially useful as certain metallization processes become more demanding. 18 ExperimentalA rotating electrochemical quartz crystal microbalance described in detail elsewhere 12 was employed using AT-cut quartz crystals (nominal resonance frequency 10 MHz) with Au electrodes. The working electrode (WE) area was 0.203 cm 2 . A Zahner potentiostat (model IM6, Germany) controlled the pulsed deposition while a PC acquired data at a frequency of 50 Hz unless noted otherwise. A mercury/mercurous sulfate electrode (MSE) acted as the reference electrode (Radiometer, France), while a Pt coil served as the counter electrode. Approximately 100 nm of Cu was deposited on the WE from the electrolyte at 2 mA/cm 2 and 1000 rpm before starting pulse experiments; direct deposition on Au gave similar results, but the reproducibility was not as good. Five pulse cycles were measured after 25 prior pulse cycles. This was found to be necessary to approach steady-state conditions. The duty cycle (the ratio of the pulse on time to the pulse period) was 20%, and the pulse period was 2 s unless noted otherwise. The off-time current density i off for all experiments was zero, while the on-time current densities i on , listed in Table I, were chosen to give an alloy composition Cu ϭ 0.5 for short pulse periods (this is discussed in more detail below). 19 ...

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Section: Discussionmentioning

confidence: 99%

Electrochemical Quartz Crystal Microbalance Study of Additive Effects in Pulsed Deposition of Cu-Co Alloys

Kelly

Kern

Landolt

2000

J. Electrochem. Soc.

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“…One possible answer is that these voids were too small to be seen by conventional in-focus imaging, and thus only the defocus contrast technique (10)(11)(12) can reveal their images. Small (0.5~5 nm) strain-free objects, such as voids, exhibit very little amplitude contrast and thus are not easily recognizable under the in-focus condition.…”

Section: Identification Of Voids Using Defocus Contrast Techniquementioning

confidence: 99%

Oxidation induced void formation in TEM specimens of Al–Cu–Li alloy

Nakahara

Tanner

Khan

et al. 2011

Materials Science and Technology

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A transmission-electron-microscope study has revealed, for the first time, the presence of small (~3 nm in diameter) voids attached to the T 1 (Al 2 CuLi) phase precipitates of an aged aluminium-copper-lithium alloy (Al-2.90%Cu-1.63%Li-0.29%Mg-0.28%Ag-0.13%Zr). These voids did not appear to form from quenched-in excess vacancies, but they were apparently nucleated at the T 1 phase/alloy interface from excess vacancies generated during oxidation. It was concluded that these voids resulted from the Kirkendall effect.

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“…Prompted by such an uncertainty in the use of defocused images, Ru¨hle 15 analyzed defocus images theoretically by formulating a defocus contrast theory and computed the image contrast of radiation-induced voids/gas bubbles. Nakahara 16,17 applied the Ru¨hle's 15 formulation and simulated the defocused images of organic molecules and voids included in electrodeposited metals.…”

Section: Introductionmentioning

confidence: 99%

“…The defocus technique has been applied previously for imaging other types of phase objects, such as voids, 15 organic impurity molecules, 16,17 impurity-segregated grain boundaries, 18,19 or magnetic domains. 20 Similar to the case of hexagonallyordered mesoporous silica particles, these objects show up by phase contrast upon defocusing.…”

Section: Introductionmentioning

confidence: 99%

“…Motivated by the lack of such studies, we modelled the entire body of a hexagonallyordered mesoporous material as a phase object and then applied this structural model to the defocus contrast theory. [15][16][17]26 The present approach is different from previous simulation work, 7,[21][22][23][24][25] in that the theoretical formulation is completely analytical as opposed to numerical. Using this theory, TEM This journal is c the Owner Societies 2011 images of the wide/narrow parallel lines observed in this material were simulated as a function of the amount/sign of defocus and specimen thickness.…”

Section: Introductionmentioning

confidence: 99%

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Defocus image contrast in hexagonally-ordered mesoporous material

Nakahara

Tanner

Hudson

et al. 2011

Phys. Chem. Chem. Phys.

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A transmission electron microscope was used to characterize a powder form of hexagonally-ordered mesoporous silica material. The structural symmetry built into this amorphous material allowed one to obtain three characteristic images, i.e. a hexagonal honey-comb structure and wide/narrow parallel lines. These images were found to originate primarily from phase contrast, which changed sensitively with defocusing. To further understand the contrast behaviour of these images, an analytical form of the defocus contrast theory was developed and applied to the simulation of the characteristic wide/narrow parallel line images. The simulation was found to be in good qualitative agreement with experiments, where changes in focus conditions and specimen thickness were predicted to alter the contrast in the resulting parallel-line type images.

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Direct Observations of Inclusions in Electrodeposited Films by Transmission Electron Microscopy

Cited by 15 publications

References 8 publications

Electrochemical Quartz Crystal Microbalance Study of Additive Effects in Pulsed Deposition of Cu-Co Alloys

Electrochemical Quartz Crystal Microbalance Study of Additive Effects in Pulsed Deposition of Cu-Co Alloys

Oxidation induced void formation in TEM specimens of Al–Cu–Li alloy

Defocus image contrast in hexagonally-ordered mesoporous material

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