Epitaxial growth of cubic WC (001) on MgO(001)

Fang, Peijiao; Wang, Baiwei; Mulligan, C.P.; Murray, Thomas M.; Khare, S. V.; Gall, Daniel

doi:10.1016/j.jallcom.2020.158403

Cited by 7 publications

(3 citation statements)

References 89 publications

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“…The Mg-to-Ti ratio was controlled by the relative power applied to two magnetrons with 5 cm-diameter 99.99% pure Mg and Ti targets. More details on the substrate preparation, the deposition system, 38,39 the film growth procedure, the composition, and the structure determination can be found in our previous publications. 40,41 Optical ultraviolet−visible−near infrared (UV−Vis−NIR) transmittance T and reflectance R spectra were collected in a Perkin-Elmer Lambda 950 photospectrometer over the wavelength range λ = 300− 3300 nm in 2.5 nm steps, using a nominally normal incident beam for T and a 6°incident angle for R measurements.…”

Section: ■ Methodsmentioning

confidence: 99%

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Tunable Infrared Plasmonic Properties of Epitaxial Ti_1–xMg_xN(001) Layers

Wang

Nawarat

Lewis

et al. 2021

ACS Appl. Mater. Interfaces

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Optical transmission and reflection spectra in combination with ellipsometry and transport measurements on epitaxial rocksalt structure Ti1–x Mg x N(001) layers with 0.00 ≤ x ≤ 0.49 are employed to explore their potential as refractory infrared plasmonic materials. A red shift in the reflection edge ℏωe from 2.0 to 0.8 eV and the corresponding unscreened plasma energy ℏωpu from 7.6 to 4.7 eV indicate a linear reduction in the free carrier density N with increasing x. However, nitrogen vacancies in Mg-rich samples act as donors, resulting in a minimum N = 1.6 × 1022 cm–3 for x = 0.49. Photoelectron valence band spectra confirm the diminishing conduction band density of states and indicate a 0.9 eV decrease in the Fermi level as x increases from 0 to 0.49. The dielectric function ε = ε1 + iε2 can be divided into a low-energy spectral region where intraband transitions result in large negative and positive ε1 and ε2, respectively, and a higher energy interband transition region with both ε1 and ε2 > 0. The screened plasma energy E ps that separates these two regions red-shifts from 2.6 to 1.3 eV for x = 0–0.39, indicating a tunable plasmonic activity that extends from the visible to the infrared (470–930 nm). Electron transport measurements indicate a metallic temperature coefficient of resistivity (TCR) for TiN-rich alloys with x ≤ 0.26 but weak carrier localization and a negative TCR <60 K for x = 0.39 and <300 K for x = 0.49, attributed to Mg alloying-induced disorder. The plasmonic quality factor Q is approximately an order of magnitude larger than what was previously reported for polycrystalline Ti1–x Mg x N, making Ti1–x Mg x N(001) layers competitive with Ti1–x Sc x N(001).

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Section: ■ Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Tunable Infrared Plasmonic Properties of Epitaxial Ti_1–xMg_xN(001) Layers

Wang

Nawarat

Lewis

et al. 2021

ACS Appl. Mater. Interfaces

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“…24 Inconel-625 and salt layer deposition.-50 nm thick Inconel-625 films are sputter deposited onto silicon-oxy-nitride Hummingbird TEM heater-chips in a ultra-high vacuum deposition system with a base pressure below 10 −8 Torr. [26][27][28] Deposition is done in 5.0 mTorr 99.999% Ar by applying a constant dc power of 200 W to a magnetron with a 5 cm diameter Inconel-625 target while maintaining the substrate temperature at 600 °C. Immediately following the deposition, the entire chip is annealed stepwise at 700 °C, 800 °C, 900 °C, and 1000 °C for 30 min each in the same vacuum system.…”

Section: Methodsmentioning

confidence: 99%

In Situ High-Temperature TEM Observation of Inconel Corrosion by Molten Chloride Salts with N₂, O₂, or H₂O

Pragnya¹,

Gall²,

Hull³

2022

J. Electrochem. Soc.

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In situ TEM is used to understand corrosion of Inconel-625 by chloride salts (MgCl2 − NaCl − KCl) at 500-800°C in 1.0 atm inert N2 or pure O2, or hydrated salts. The isothermal corrosion rate R in inert N2 increases from 203 ± 30 μm year-1 at 700°C to 463 ± 30 μm year-1 at 800°C. An oxygen ambient causes a six-fold increase to R = 1261 ± 170 μm year-1. Salt hydration dramatically accelerates corrosion to R > 3×105 μm year-. These isothermal corrosion rates indicate that the molten chloride corrosion is significantly accelerated by salt hydration at temperatures above 600°C. To reduce the rate of corrosion it is important to both avoid incorporation of H2O into the system and ensure proper flushing before increasing the temperature beyond 600°C. In addition, steps should be taken to tailor chloride melt compositions that has low solubility for HCl and O2. All of our corroded samples exhibit passive-protective oxide layers of Cr, Mg, and Ni. In addition, distinct volatile compounds are detected. To minimize corrosion formation of volatile by-products should be avoided.

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