Corrosion characterization of durable silver coatings by electrochemical impedance spectroscopy and accelerated environmental testing

Chu, Constance R.; Fuqua, Peter D.; Barrie, James D.

doi:10.1364/ao.45.001583

Cited by 45 publications

(24 citation statements)

References 6 publications

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“…Therefore, in a first approach, the interface between the silver/Si 3 N 4 /electrolyte can be represented by the classical equivalent circuit shown in Figure 7 proposed for the first time in reference26 and used in references. [18][19][20][21][22] The impedance corresponding to the proposed model ( Figure 7) can be written as…”

Section: Results and Analysismentioning

confidence: 99%

“…They used an equivalent circuit that took into account both open and closed pores. Tse Chu et al 22 showed that dielectric protected silver reflectors can be reasonably described by an equivalent circuit consisting of two constant phase element (CPE) components. They considered only the modulus of the impedance to characterize the electrochemical behavior of the dielectric film.…”

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confidence: 99%

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Interpretation of Electrochemical Impedance for Corrosion of a Coated Silver Film in Terms of a Pore-in-Pore Model

Amor

Sutter

Takenouti

et al. 2014

J. Electrochem. Soc.

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Electrochemical impedance spectroscopy was used to study the degradation behavior of thin multilayer stacks; Si 3 N 4 /Ag/Si 3 N 4 . Measurements were carried out in 0.5 M Na 2 SO 4 adjusted at pH 10. The impedance data collected at the open circuit potential were analyzed with a physical model where all elements are clearly defined. The results suggest a constant phase element behavior at the electrolyte dielectric interface assigned to an in-depth distribution of local resistivity through the dielectric layer induced by the electrolyte penetration. To explain the electrochemical behavior of the thin silver layer, a localized corrosion in a delaminated zone between the upper dielectric and the silver layers was adopted. The localized corrosion was found to be related to the granular structure of the silver layer in which pores are formed between the grains of silver. This model is equivalent to a recently developed double porosity or pore-in-pore model.Thin film deposition of metallic, dielectric, and semiconducting materials is widely used in many applications, including microelectronic devices, optical coatings, solar cells, and thin-film batteries. [1][2][3][4] Silver is the most used metal for industrial optical applications. This metal possesses the highest reflectivity, from 400 nm through the IR, and the lowest polarization splitting among all metals. 5 Silver also has the lowest emissivity of all metals in the visible and IR regions. However, in aggressive environments, a silver layer is susceptible to deterioration. This deterioration depends on many factors, such as pH, humidity, temperature, type and concentrations of pollutants, and exposure time. [6][7][8][9][10][11][12][13][14][15] To study the degradation behavior of silver thin films in such environments, different analytical methods are commonly employed. The most commonly used techniques are transmission electron microscopy, atomic force microscopy, and recently time-of-flight secondary ion mass spectrometry. 16,17 These various techniques provide only very local information and often require complex sample preparation. Recently, electrochemical methods, and, more specifically, electrochemical impedance spectroscopy (EIS), have emerged as an alternate way to study material and interface properties of thin film stacks. [18][19][20] The interpretation of EIS results is usually done through the construction of equivalent electric circuits that simulate the system under investigation. This allows the extraction of physical parameters related to the film microstructure that are not easily accessible by other techniques. 21 For instance, Zeng et al. 18 show that EIS can be applied to measure the nano-porosity of diamond-like carbon films deposited on silicon substrates. They used an equivalent circuit that took into account both open and closed pores. Tse Chu et al. 22 showed that dielectric protected silver reflectors can be reasonably described by an equivalent circuit consisting of two constant phase element (CPE) components. They considered only ...

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Section: Results and Analysismentioning

confidence: 99%

mentioning

confidence: 99%

Interpretation of Electrochemical Impedance for Corrosion of a Coated Silver Film in Terms of a Pore-in-Pore Model

Amor

Sutter

Takenouti

et al. 2014

J. Electrochem. Soc.

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“…There are numerous approaches to developing protected silver coatings which combine an effective protection of the silver film with good optical properties. Several investigations of the durability of protected silver have already been published [4,5,[7][8][9][10]. The most investigated coatings are based on the patented coating design from Wolf et al [6].…”

Section: B Investigation Of a Defect Mechanism In Protected Silver Cmentioning

confidence: 99%

“…the Gemini twins or the Kepler Space Telescope [4,5], are using mirrors with this kind of coating. However, even though protected silver coatings were extensively studied and optimized in the recent years, the appearance of defects after extensive exposure of protected silver mirrors to humid atmosphere remains still an important topic [7].…”

Section: B Investigation Of a Defect Mechanism In Protected Silver Cmentioning

confidence: 99%

High-reflective coatings for ground and space based applications

Schürmann

Schwinde

Jobst

et al. 2017

International Conference on Space Optics — ICSO 2014

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“…However, NiCr nitride has very poor transmission in the optical wavelengths; as a consequence, the upper layer must be exceedingly thin. Chu et al 7 report that as little as 3 Å (ie. just 1-2 atomic thicknesses!)…”

Section: Silver: the Gemini/llnl Style Coatingmentioning

confidence: 99%

Progress toward high-performance reflective and anti-reflection coatings for astronomical optics

et al. 2008

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There is a continued need for efficient reflective and anti-reflection (AR) coatings for increasingly large optics in astronomy. The requirements for these coatings differ in several respects from those developed for commercial use. In general, they require a broad spectral coverage, high-efficiency, long life under semi-exposed conditions, and the ability to be removed without damage to expensive substrates. UCO/Lick Observatory has undertaken an effort to develop improved coatings for astronomical optics. In this paper, we report on progress toward (a) robust protected silver coatings for telescopes; (b) enhanced silver and aluminum coatings for instruments; and (c) hardened sol-gel AR coatings. Examples of some of our new coatings are in use at Lick and Keck Observatories. The problems involved in successful coatings are multifaceted and we summarize our major findings to date. This includes our requirements, test procedures, and performance and durability results for the three types of coatings mentioned.

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Corrosion characterization of durable silver coatings by electrochemical impedance spectroscopy and accelerated environmental testing

Cited by 45 publications

References 6 publications

Interpretation of Electrochemical Impedance for Corrosion of a Coated Silver Film in Terms of a Pore-in-Pore Model

Interpretation of Electrochemical Impedance for Corrosion of a Coated Silver Film in Terms of a Pore-in-Pore Model

High-reflective coatings for ground and space based applications

Progress toward high-performance reflective and anti-reflection coatings for astronomical optics

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