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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Structure and cathodoluminescent properties of ultraviolet emitting Zn(Al<inf>1-x</inf> Ga<inf>x</inf>)<inf>2</inf> O<inf>4</inf> alloy phosphor
摘要： The goal is to control the band gap by replacing the Al site of zinc aluminate having a spinel structure with Ga, and to control the emission wavelength, and aim for application as a light source in sterilization, skin treatment and the like. Zn(Al1-xGax)2O4 phosphor was prepared by a solid phase synthesis method. A plurality of samples with different Al/Ga ratio were prepared, and their crystal structures and luminescent properties were evaluated. In X-ray diffraction, formation of a single phase was confirmed in the sample fired at 1300 oC. It was confirmed that the diffraction peak shifted to the lower angle side by increasing the Ga ratio. In the cathode luminescence method, it was confirmed that ultraviolet emission of ZnAl2O4 was confirmed at about 250 nm, and it was confirmed that the emission wavelength shifted to the long wavelength side by increasing the Ga ratio. It is suggested that substituting Ga for the Al site of ZnAl2O4 is useful for shifting the emission wavelength although the emission intensity is unstable.
关键词： Cathodoluminescence,Zn(Al,Ga)2O4,Alloy phosphor,Ultra-Violet emission
更新于2025-09-23 15:21:21
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Atomic resolution enabled STEM imaging of nanocrystals at cryogenic temperature
摘要： In this study, we address the problem of electron-beam induced damage on two energy-related materials: LiNi0.5Mn1.5O4 used as a cathode material for lithium-ion batteries and ZnCo1.8Ni0.2O4 used as a catalyst for oxygen evolution reaction. Both materials were found to transform from the spinel into the rocksalt phase while being imaged by high-resolution scanning transmission electron microscopy (HR-STEM) at room temperature. To mitigate the degradation, we found HR-STEM characterization at cryogenic temperature delays the critical electron dose for structural modification. We determined the native phase of materials to be spinel while the other phases observed by HR-STEM were induced by the electron-beam. From a careful analysis of the experimental data and a detailed understanding of the different degradation processes induced by an energetic electron beam, we conclude that radiolysis is the mechanism responsible for the degradation in LiNi0.5Mn1.5O4 and ZnCo1.8Ni0.2O4 nanoparticles.
关键词： LiNi0.5Mn1.5O4,ZnCo1.8Ni0.2O4,electron beam degradation,cryo-STEM
更新于2025-09-23 15:19:57
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Systematic tuning of the photo-dielectric effect in Ba(Al <sub/>1–</sub><sub/><i>x</i> </sub> Zn <sub/><i>x</i> </sub> ) <sub/>2</sub> O <sub/>4–δ</sub>
摘要： Systematic tuning of photo-induced enhancement of the dielectric permittivity (i.e., the photo-dielectric effect) in Ba(Al1–xZnx)2O4–d (BAZ-x) has been demonstrated by changing Zn concentration x and intensity of the incident light. The relative change of the dielectric permittivity (e0), defined as De0/dark, increases linearly with an increase in the Zn concentration (x), finally reaching approximately 30% at 1 MHz. The dependence of De0/dark on the intensity of the incident light shows a two-step growth as the irradiation light intensity increases, suggesting the existence of multiple photo-induced processes influencing the photo-dielectric effect of BAZ-x. The results of the present study not only give a clue to the mechanism of the photo-dielectric effect but also aid in the development of innovative photo-tunable functional devices.
关键词： light intensity,dielectric permittivity,Zn concentration,photo-dielectric effect,Ba(Al1–xZnx)2O4–d
更新于2025-09-10 09:29:36