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Stabilizing the Plasmonic Response of Titanium Nitride Nanocrystals with a Silicon Oxynitride Shell: Implications for Refractory Optical Materials
摘要： We discuss the synthesis and properties of nanoparticles and thin films for refractory plasmonic applications. The approach focuses on titanium nitride (TiN), which overcomes the limitations of more common plasmonic materials like silver and gold with respect of temperature stability. Free-standing TiN-based nanoparticles are produced in two serially connected plasma reactors, where TiN nanocrystals are nucleated in a first plasma stage, then aerodynamically dragged in a second stage and conformally coated with a silicon nitride layer. An in-depth comparison between bare and coated TiN nanoparticles is presented in terms of the structural, chemical and optical properties. Coating of the titanium nitride core reduces its oxidation upon exposure to air, drastically improving plasmonic response. Thin films realized using the core-shell structure show practically no change in reflectivity even when the thin films are heated to 900°C in an inert atmosphere. This study introduces a simple surface passivation schemes that enhances the functionality of the material, providing further confirmation of the potential of nitride-based plasmonic material as high-quality refractory optical compounds for a broad range of applications.
关键词： Titanium nitride,Non-thermal plasma,Thin films,Nanocrystals,Refractory nanomaterials,Plasmonic nanomaterials
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE Pulsed Power & Plasma Science (PPPS) - Orlando, FL, USA (2019.6.23-2019.6.29)] 2019 IEEE Pulsed Power & Plasma Science (PPPS) - Laser Thomson Scattering Diagnostics for Streamer Discharge in HE Gas
摘要： Streamer discharge plasma, a type of non-thermal plasma, has received global attention as a source of reactive radicals, and is used for many applications such as ozone generation, decomposition of NOx and other gas pollutants, cleaning water, disinfection, deodorization, and medical applications. The tip of streamer discharge, known as the streamer head, in particular contributes to radical production. The peak electric field is located on the streamer head on the axis of symmetry of the discharge, likely resulting in many radical types. Very remarkable results in NO removal efficiency and superior ozone generation yield performed by streamer discharge have reported. Improving gas treatment methods requires understanding of physical characteristics of streamer discharge and streamer head, for example, electron temperature and electron density. This study investigates characteristics of streamer discharge by observing the propagation process of streamer head in a needle to conic electrode with positive voltage using a high speed gated emICCD camera. Then, incoherent laser Thomson scattering (LTS) diagnostic for streamer discharge and streamer head with positive voltage was performed. LTS diagnostic is considered to be the most reliable technique measuring electron temperature and density in plasma simultaneously. In addition, LTS diagnostic has high resolution temporally and spatially, therefore, LTS diagnostic can measure location dependence of electron temperature and density in streamer discharge including streamer head. The measurement point was 1 mm and 2 mm from tip of the high voltage needle electrode, and Thomson scattering signals were measured at the point of initial phase of streamer head propagation. In the results, electron temperature of streamer discharge was 4 to 6 eV, electron density of streamer discharge was 1021 m-3 order. This study has proven that LTS diagnostic can measure electron temperature and density in streamer discharge plasma.
关键词： Streamer discharge,Electron temperature,Laser Thomson scattering,Non-thermal plasma,Electron density
更新于2025-09-23 15:19:57
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High-density cascade arc plasma sources for application to plasma windows for virtual vacuum interfaces
摘要： We develop two cascade arc plasma sources for application to plasma windows for virtual vacuum interfaces. For windowless vacuum–atmosphere separation, a compact arc discharge source having a channel diameter of 3 mm is fabricated, and an atmospheric Ar thermal plasma is generated. For an alternative differential pumping system, separating low- and high-pressure vacuum chambers, a larger arc device with an 8-mm diameter is also constructed, producing a high-density He plasma. The performances of the two cascade arcs as plasma windows are investigated. The 3-mm arc discharge generates a steep pressure gradient of Ar 100 kPa–100 Pa through the discharge channel, while the 8-mm discharge apparatus isolates the high-pressure side at 7 kPa from the lower pressure of 54 Pa. Emission spectroscopy of visible and vacuum UV radiation reveals the characteristics of the Ar and He plasmas. Spectral analysis yields a plasma temperature of around 1 eV in both discharges. Stark broadenings of the H-b and Ar I lines give an electron density of 6.5 (cid:2) 1016 cm(cid:3)3 for Ar 60 A with a gas ?ow rate of 1.0 l/min and 4.7 (cid:2) 1013 cm(cid:3)3 under a He 100-A and 0.45-l/min condition.
关键词： electron density,plasma temperature,emission spectroscopy,virtual vacuum interfaces,He plasma,cascade arc plasma sources,plasma windows,Ar thermal plasma
更新于2025-09-04 15:30:14