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Laser-induced Si3N4–TiN ceramics degradation
摘要： This paper presents the process of degradation of the surface layer of Si3N4?TiN ceramics induced by a pulsed Nd:YAG laser. The dissociation of silicon nitride and titanium nitride in the irradiation zone is turned out to yield in a silicon depletion and so the zone becomes enriched with titanium, which, in turn, leads to the formation of TiSi2. This process of the TiSi2 formation can be considered as a ceramics metallization and its concentration depends on the energy delivered by the laser. The expansion of dissociation/evaporation products through the atmosphere is accompanied by the formation of SiO2 and TiO2, which are then deposited on the substrate as an amorphous ?lm of complex composition.
关键词： Surface phase transformation,(Si3N4 ? TiN):(Al2O3+Y2O3) ceramics,Film formation
更新于2025-09-12 10:27:22
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Enhanced photovoltaic performance of Y2O3:Ho3+/Yb3+ upconversion nanophosphor based DSSC and investigation of color tunability in Ho3+/Tm3+/Yb3+ tridoped Y2O3
摘要： The present study reports the upconversion (UC) based color tuning in Y2O3:Ho3+/Yb3+, Y2O3:Tm3+/Yb3+ and Y2O3:Tm3+/Ho3+/Yb3+ phosphors synthesized through complex based precursor solution method. The Y2O3:Ho3+/Yb3+ phosphor emits intense green and weak red colors whereas the Y2O3:Tm3+/Yb3+ emits NIR and blue colors on excitation with 976 nm. The impact of the enhancement in the concentration of Yb3+ on the color point of codoped as well as tridoped phosphors has been studied in detail. When Y2O3:Tm3+/Ho3+/Yb3+ phosphor is excited by 976 nm laser, the phosphor emits dominant green color. This is due to energy transfer from Tm3+ to Ho3+ ions. The increase in the concentration of Yb3+ ion leads to a color tunability not only in the co-doped but also in the tridoped phosphors. Furthermore, we have incorporated Y2O3:Ho3+,Yb3+ UC phosphor into TiO2 electrode to form an UC based DSSC for converting near IR (NIR) light into visible where DSSCs typically have high sensitivity. The short-circuit current density (Jsc) as well as the open-circuit voltage (Voc) of the UC-TiO2 based cell was found to be 8.46% and 5.18% higher which in turn, resulted into a 10.33% enhancement in power conversion efficiency as compared to that of bare TiO2 based DSSC. Thus, the UC based Y2O3:Ho3+/Yb3+ may be useful in color tunability and DSSC applications.
关键词： Upconversion,Photovoltaic performance,Color tuning,DSSC,Y2O3:Ho3+/Yb3+
更新于2025-09-11 14:15:04
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In-situ synthesis and enhanced upconversion luminescence of Y2O3/Y2O2S:Yb3+,Er3+/Tm3+ nanocomposites by reduction of Y2O3:Yb3+,Er3+/Tm3+
摘要： Y2O3/Y2O2S:Ln3+ (Ln = Yb,Er and Yb,Tm) nanocomposites with enhanced upconversion luminescence were successfully prepared by combining hydrothermal with in-situ synthesis method. Under 980 nm excitation, the upconversion luminescence intensity of Y2O3/Y2O2S:Ln3+ increased, and then declined with the rising amount of sulfur powder. Especially, the Y2O3/Y2O2S:Ln3+ nanocomposites can emit brighter upconversion luminescence than those of Y2O3:Ln3+ and Y2O2S:Ln3+. In terms of Y2O3/Y2O2S:Yb3+,Er3+ nanocomposites which were prepared with 0.025g sulfur powder, an unusual 4G11/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3+ could be observed. Besides, we have constructed a simple upconversion Y2O3/Y2O2S:Yb3+,Er3+@Au nanocomposite, which can be used for rapid sensing of glucose. The limit of detection of glucose level which based on Y2O3/Y2O2S:Yb3+,Er3+@Au was only 0.066 μmol/L. The proposed approach, which we have mentioned above, holds a great practical value for diabetes mellitus detection and clinical diagnosis.
关键词： B. Upconversion luminescence,A. Y2O3/Y2O2S:Yb3+Er3+,D. Glucose detection
更新于2025-09-10 09:29:36
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High-temperature high pressure synthesis of monoclinic Y2O3
摘要： In this work, synthesis of cubic Y2O3 by calcining yttrium based coordination polymer (Y-CP) which were obtained by microwave-assisted method was reported. Monoclinic Y2O3 was obtained by treating the cubic Y2O3 under high temperature high pressure (HTHP) on a large volume cubic multi-anvil high pressure apparatus. The effect of temperature on the preparation was studied. The morphology and crystal phase of all samples have been characterized by the scanning electron microscope (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) spectra. What more, the photoluminescence (PL) property of the Y2O3: Eu3+ sample was investigated. This method can be used to prepare other rare earth oxide with various phase.
关键词： Coordination polymer,luminescence,Y2O3,high temperature high pressure,Phase transformation
更新于2025-09-04 15:30:14