- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Enhanced red luminescence by gamma irradiation on GdPO4:Er3+@SiO2 nanophosphor
摘要： The influence of gamma radiation on enhancement of red emission from Er3+ doped GdPO4@SiO2 nanophosphors was investigated. The luminescent emission was recorded after photoexcitation at 462 nm. The strong red luminescence at 690 nm corresponds to 4F9/2 → 4I15/2 transition. The luminescence intensity of the prepared phosphor had enhanced 2-4 folds and 4-6 fold after exposing to 150 kGy and 300 kGy gamma radiation, respectively. A linear response between luminescence intensity and irradiation dose was observed through PL dosimetry study. These biocompatible nanophosphors may have promising applications in biomedical and optoelectronic fields.
关键词： Nanophosphor,Gamma radiation,GdPO4,Erbium,Photoluminescence,SiO2
更新于2025-09-09 09:28:46
-
Infrared spectroscopy of ion tracks in amorphous SiO2 and comparison to gamma irradiation induced changes
摘要： Ion track formation in amorphous SiO2was investigated using infrared spectroscopy. For comparison, one set of samples was also irradiated using 1.25 MeV gamma rays. An increase of 1044 cm-1 peak and decrease of 1078 cm-1 peak was observed in all cases. Experimental results were analysed using an analytical thermal spike model and non-standard model parameters were found. This finding is attributed to the amorphous structure of the material.
关键词： gamma rays,ion track,amorphous SiO2,infrared spectroscopy,thermal spike,swift heavy ion
更新于2025-09-09 09:28:46
-
Plasma enhanced chemical vapor deposition of SiO <sub/>2</sub> and SiN <sub/>x</sub> on AlGaN: Band offsets and interface studies as a function of Al composition
摘要： In this work, the authors characterized the interface of plasma enhanced chemical vapor deposition (PECVD) dielectrics, SiO2 and SiNx with AlGaN as a function of Al composition. SiO2 is found to exhibit type I straddled band alignment with positive conduction and valence band offsets for all Al compositions. However, the interface Fermi level is found to be pinned within the bandgap, indicating a significant density of interface states. Hence, SiO2 is found to be suitable for insulating layers or electrical isolation on AlGaN with breakdown fields between 4.5 and 6.5 MV cm?1, but an additional passivating interlayer between SiO2 and AlGaN is necessary for passivation on Al-rich AlGaN. In contrast, Si-rich PECVD SiNx is found to exhibit type II staggered band alignment with positive conduction band offsets and negative valence band offsets for Al compositions <40% and type I straddled band alignment with negative conduction and valence band offsets for Al compositions >40% and is, hence, found to be unsuitable for insulating layers or electrical isolation on Al-rich AlGaN in general. In contrast to passivating stoichiometric LPCVD Si3N4, no evidence for interface state reduction by depositing SiNx on AlGaN is observed.
关键词： PECVD,band offsets,SiO2,AlGaN,interface studies,Al composition,SiNx
更新于2025-09-09 09:28:46
-
Research on cracking of SiO2 nanofilms prepared by the sol-gel method
摘要： SiO2 nano?lms were prepared by a sol-gel method with TEOS as the precursor, ethanol as the solvent, and hydrochloric acid as the catalyst. The in?uences of H2O, EtOH, and HCl on the surface of SiO2 ?lm were studied by a controlled variable method, and the e?ects of aging time, spin-coating speed, ammonia treatment, heat treatment, and substrate on the ?lms were also determined experimentally. Crack-free SiO2 nano?lms with tens of microns thickness were repeatedly fabricated using the optimizing parameters, and the size of SiO2 nano-particles was in the range of 100–500 nm.
关键词： SiO2 nano?lm,Sol-gel method
更新于2025-09-09 09:28:46
-
Nucleation of diindenoperylene and pentacene at thermal and hyperthermal incident kinetic energies
摘要： The authors have examined the nucleation of diindenoperylene (DIP) on SiO2 employing primarily atomic force microscopy and focusing on the effect of incident kinetic energy employing both thermal and supersonic sources. For all incident kinetic energies examined (Ei ? 0.09–11.3 eV), the nucleation of DIP is homogeneous and the dependence of the maximum island density on the growth rate is described by a power law. A critical nucleus of approximately two molecules is implicated by our data. A re-examination of the nucleation of pentacene on SiO2 gives the same major result that the maximum island density is determined by the growth rate, and it is independent of the incident kinetic energy. These observations are readily understood by factoring in the size of the critical nucleus in each case, and the island density, which indicates that diffusive transport of molecules to the growing islands dominate the dynamics of growth in the submonolayer regime.
关键词： thermal,SiO2,supersonic sources,diindenoperylene,hyperthermal,kinetic energies,nucleation,atomic force microscopy,pentacene
更新于2025-09-09 09:28:46
-
Single electron transistors with e-beam evaporation of SiO <sub/>2</sub> tunnel barriers
摘要： Recent work on fabricating metal-insulator-metal (MIM) single electron transistors (SETs) using deposited dielectrics shows promise for becoming a manufacturable process due to compatibility with modern CMOS processes. This process, the “rib-SET” process [V. Joshi, A. O. Orlov, and G. L. Snider, J. Vac. Sci. Technol. B 26, 2587 (2008); G. Karbasian, A. O. Orlov, and G. L. Snider, J. Vac. Sci. Technol. B 33 (2015)], features a self-aligned island and should allow for scaling SETs below 10 nm. However, one of the biggest roadblocks in realizing a high-quality SET with this process has been dif?culties in developing high-quality, low-noise, MIM tunnel junctions. In this work, the authors report Pt-SiO2-Pt MIM SETs with tunnel barriers deposited by e-beam evaporation as an alternative to atomic layer deposition. There are some challenges in the formation of tunnel barriers via e-beam evaporation that are addressed. It is expected that platinum has a negligible native oxide; however, there is a substantial resistance in as-deposited Pt-SiO2-Pt structures that can be reduced by over 5 orders of magnitude by subjecting the ?nished devices to an anneal in a hydrogen plasma, suggesting the presence of an interfacial platinum oxide. It is shown that this treatment not only increases the conductance through the SET, but that it is necessary for forming high conductance tunnel barriers that are desired for making low-noise SETs.
关键词： single electron transistors,metal-insulator-metal,e-beam evaporation,SiO2 tunnel barriers,CMOS processes
更新于2025-09-09 09:28:46
-
Dual-Bandgap Effect of Photonic Crystals on TiO2 Photocatalytic Activity in Ultraviolet and Visible Light Regions
摘要： Photonic crystals (PCs) have promising characteristic to raise the light harvest of materials. PCs with one photonic band gap (PBG) were usually used to enhance the light harvest of materials. In this research work, we used PCs with dual PBGs to increase the light harvest. SiO2 PCs with dual PBGs were constructed through depositing a SiO2 PCs layer on another SiO2 PCs layer by vertical deposition method. Then the bi-layer structured SiO2 PCs were composited with nanocrystalline TiO2 film which was sensitized by CdS quantum dots (QDs) (Q-T), to produce photocatalyst for photodegradation of gaseous acetaldehyde. By adjusting the PBGs of the bi-layer SiO2 PCs, namely one PBG matching with the absorption edge of TiO2 and another PBG matching with the absorbing range of CdS QDs, the photocatalytic activity of the composite film under white light irradiation was increased to 2.11 times of that of the control photocatalyst (the Q-T film coated on a disordered porous SiO2 film). When Q-T film was coupled with a monolayer SiO2 PCs, which has single PBG centered at TiO2’s electronic band gap (EBG) of 380 nm, its photocatalytic activity was increased by 1.34 times. When coupled with a monolayer SiO2 PC with the PBG centering at the EBG of CdS QDs (465 nm), the photo-catalytic activity of the Q-T film was increased by 1.54 times. Because the SiO2 PCs with dual-PBGs can simultaneously enhance the light harvest in ultraviolet and visible light region, the Q-T film coupled with dual-PBGs SiO2 PCs showed the highest activity.
关键词： Photocatalyst,SiO2 Opal,Dual photonic band gaps,TiO2,Photonic crystals
更新于2025-09-09 09:28:46
-
Effect of Calcination Temperature in Preparation of ZnO-SiO2/Laponite and its Physical Character and Photocatalytic Activity
摘要： ZnO-SiO2/laponite was prepared by sol-gel preparation procedure consit of SiO2 pillarization to laponite followed by ZnO dispersion by using zinc acetate as precursor. The obtained material was characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, diffuse reflectance UV-visible (DRUV-visible) and N2 adsorption-desorption analysis. The photocatalytic performance of the material in decolorization of methylene blue was also investigated. Compared with ZnO-SiO2 nanoparticles, it is concluded that ZnO-SiO2/laponite possess higher photocatalytic activity and influenced by calcination temperature.
关键词： Photocatalyst,Pillarization,Laponite,Clay,ZnO-SiO2
更新于2025-09-09 09:28:46
-
Residual stress in underlying silicon at the fixed end of SiO <sub/>2</sub> microcantilevers?— A micro-Raman study
摘要： In this work, nature of the residual stress developed in the convex corners created in underlying Si at the fixed end of SiO2 microcantilevers (MCs) fabricated by wet chemical etching method was investigated using micro-Raman spectroscopy with visible excitation. It revealed the presence of tensile stress near the sharp edge of the convex corner and is attributed to the localized stress generated in the neighborhood of the discontinuities, acting as stress concentration region. Residual stress estimated by micro-Raman technique across the convex corner was also validated by FEM simulations. Micro-Raman also revealed the presence of tensile stress on the etched Si surface, which is explained on the basis of stress induced by native oxide shells covering the etched features.
关键词： SiO2 microcantilever,convex corner in Si,micro-Raman spectroscopy using visible excitation,residual stress
更新于2025-09-04 15:30:14
-
Bandgap Tailored TiO2 Thin Films by Addition of SiO2 for Enhanced Photocatalytic Activity against Congo Red under Visible Light Illumination
摘要： Colloidal solutions of SiO2-TiO2 mixed oxides having different SiO2 contents were synthesized by sol-gel technique and thin films were deposited over glass slides by using dip coating technique. The films were subjected to high temperature at 400 °C for growing TiO2 crystals. Energy dispersive X-ray spectroscopy was used to indicate the elements in the films. X-ray diffraction analysis indicated that SiO2-TiO2 films contain only anatase phase. Scanning electron microscopy was used to study the films surface morphology. The SiO2-TiO2 films that were contacted with congo red (5 ppm) and irradiated with visible light showed a high photocatalytic activity. UV spectrophotometry technique was used to monitor the degradation of congo red by the reduction of main absorbance peak at 497 nm. Complete degradation was achieved after 2 h for 3 mol % SiO2-TiO2 thin film.
关键词： Congo red,SiO2,Dip coating,TiO2,Photocatalytic activity
更新于2025-09-04 15:30:14