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Broadband light emission induced by laser absorption and optimized by thermal injection in Nd <sup>3+</sup> :Y <sub/>2</sub> SiO <sub/>5</sub> ceramic powder
摘要： Laser induced broadband (white) light emission has been studied in different particle systems for use in light emitting devices. The photoinduced phenomenon occurs above a certain excitation power threshold and it is generally studied under vacuum conditions. In this work, the phenomenon is studied in neodymium doped yttrium silicate ceramic powder synthesized by combustion method. White light is observed when the sample is excited in ambient air with a CW near-infrared (λ = 808 nm) laser powered above 1.3 W. When the temperature of the sample is externally raised above 200 oC, white light is observed above 1.0 W and a large enhancement of the broadband emission intensity is observed.
关键词： broadband emission,up-conversion,neodymium doped yttrium silicate,laser induced,thermal injection
更新于2025-09-11 14:15:04
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Efficacy of erbium-doped yttrium aluminum garnet laser with casein phosphopeptide amorphous calcium phosphate with and without fluoride for remineralization of white spot lesions around orthodontic brackets
摘要： Objective: This study aimed to assess the efficacy of erbium?doped yttrium aluminum garnet (Er:YAG) laser, pastes containing casein phosphopeptide amorphous calcium phosphate (CPP?ACP) with and without fluoride and their combination for prevention of white spot lesions in the enamel. Materials and Methods: This in vitro experimental study was conducted on 90 extracted sound premolars. The teeth were then randomly divided into six groups of 15: (1) Control, (2) laser, (3) CPP?ACP with fluoride (GC MI Paste, Recaldent? 900 ppm as NaF), (4) CPP?ACP without fluoride (GC Tooth Mousse Recaldent?), (5) laser + CPP?ACP with fluoride, and (6) laser + CPP?ACP without fluoride. In each group, enamel surface was exposed to the remineralizing agent. The teeth were then subjected to pH cycling for 14 days. The teeth were then sectioned, polished, and underwent cross?sectional microhardness testing at 20–160 μ depth quantitatively. Using the Simpson’s rule, the amount of mineral loss was calculated in each group. Statistical Analysis Used: ANOVA was used for the comparisons, and Tukey’s test was applied for pairwise comparisons. Results: The highest mean volume percentage of microhardness at 20–60 μ depth belonged to the group laser + CPP?ACP with fluoride and the lowest belonged to the control group (P = 0.001). The differences were not significant at 80?120 μ depth (P > 0.05). These finding are confirmed according to ?Z (mineral loss). Conclusion: Based on these results, Er: YAG laser was able to decrease demineralization and was a potential alternative to preventive dentistry and was more effective when combined with CPP?ACP products.
关键词： Casein phosphopeptide amorphous calcium phosphate,white spot lesion,erbium-doped yttrium aluminum garnet laser
更新于2025-09-11 14:15:04
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Enhancing the Performance of Textured Silicon Solar Cells by Combining Up-Conversion with Plasmonic Scattering
摘要： This paper experimentally demonstrates the bene?ts of combining an up-conversion (UC) layer containing Yb/Er-doped yttrium oxide-based phosphors with a plasmonic scattering layer containing indium nanoparticles (In-NPs) in enhancing the photovoltaic performance of textured silicon solar cells. The optical emissions of the Yb/Er-doped phosphors were characterized using photoluminescence measurements obtained at room temperature. Optical microscope images and photo current-voltage curves were used to characterize the UC emissions of Yb/Er-doped phosphors under illumination from a laser diode with a wavelength of 1550 nm. The plasmonic e?ects of In NPs were assessed in terms of absorbance and Raman scattering. The performance of the textured solar cells was evaluated in terms of optical re?ectance, external quantum e?ciency, and photovoltaic performance. The analysis was performed on cells with and without a UC layer containing Yb/Er-doped yttrium oxide-based phosphors of various concentrations. The analysis was also performed on cells with a UC layer in conjunction with a plasmonic scattering layer. The absolute conversion e?ciency of the textured silicon solar cell with a combination of up-conversion and plasmonic-scattering layers (15.43%) exceeded that of the cell with an up-conversion layer only (14.94%) and that of the reference cell (14.45%).
关键词： plasmonic scattering,up-conversion,indium nanoparticles,phosphors,photovoltaic performance,yttrium oxide
更新于2025-09-11 14:15:04
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On the influence of local oxygen addition on the growth of sputter deposited yttrium oxide thin films
摘要： Yttrium oxide thin films are grown by reactive magnetron sputtering. To achieve a high deposition rate, target poisoning is avoided by local oxygen addition at the substrate. In all deposited thin films only the monoclinic Y2O3 phase is observed. A strong variation in the film texture across the sample for experiments with a stationary sample stage is noticed. This inhomogeneity can be partially traced back to an uneven oxygen gas distribution. Sample rotation resolves this problem, but still the gas distribution influences both the texture and the Bragg peak positions. Several configurations for the gas supply are tested with a different number of gas distribution pipes. An overview of all experiments shows an interesting correlation between the texture coefficient and the peak position of the monoclinic (111) Bragg reflection. When the peak shifts towards higher diffraction angles, the texture coefficient drops as a higher contribution of the (402) orientation is observed. This trend however is further complicated by the exact geometrical configuration on the deposition rate, and the energy/momentum of the species arriving at the substrate. As previously reported, an increasing energy/momentum per deposited atom results in monoclinic thin films with a preferential (111) out-of-plane orientation.
关键词： Texture,Yttrium oxide,Magnetron sputtering,Gas distribution
更新于2025-09-11 14:15:04
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Zirconium distribution in solution-derived BaZrO3 - YBa2Cu3O7-δ epitaxial thin films studied by X-ray photoelectron spectroscopy
摘要： Superconducting YBa2Cu3O7-δ films with different amounts of BaZrO3 nanoinclusions were deposited on SrTiO3(001) by low-fluorine chemical solution deposition with the aim of introducing artificial vortex pinning centres. The Zr concentration over the film thickness could be determined by X-ray photoelectron spectroscopy combined with Ar+ ion etching. The Zr/Y ratio has a constant behaviour in the film's bulk. Zr segregation occurs near the surface and Zr diffusion into the substrate is observed near the interface. Conversely, Sr and Ti from the substrate diffuse into the films. Y3d lineshape analysis and X-Ray Diffraction data pointed out that Ti diffusion causes the formation of Y-Ti-O based spurious phases.
关键词： Chemical solution deposition,X-ray photoelectron spectroscopy,Vortex pinning,Yttrium barium copper oxide,Barium zirconate
更新于2025-09-10 09:29:36
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Effects of collimator on imaging performance of Yttrium-90 Bremsstrahlung photons: Monte Carlo simulation
摘要： Yttrium-90 is a useful therapeutic radioisotope for tumor treatment because of its high-energy-emitting beta rays. However, it has been dif?cult to select appropriate collimators and main energy windows for Y-90 Bremsstrahlung imaging using gamma cameras because of the broad energy spectra of Y-90. We used a Monte Carlo simulation to investigate the effects of collimator selection and energy windows on Y-90 Bremsstrahlung imaging. We considered both MELP and HE collimators. Various phantoms were employed in the simulation to determine the main energy window using primary-to-scatter ratios (PSRs). Imaging performance was evaluated using spatial resolution indices, imaging counts, scatter fractions, and contrast-to-noise ratios. Collimator choice slightly affected energy spectrum shapes and improved PSRs. The HE collimator performed better than the MELP collimator on all imaging performance indices (except for imaging count). We observed minor differences in SR and SF values for the HE collimator among the ?ve simulated energy windows. The combination of an HE collimator and improved-PSR energy window produced the best CNR value. In conclusion, appropriate collimator selection is an important component of Bremsstrahlung Y-90 photon imaging and main energy window determination. We found HE collimators to be more appropriate for improving the imaging performance of Bremsstrahlung Y-90 photons.
关键词： Gamma camera,Collimator,Energy window,Yttrium-90,Bremsstrahlung imaging
更新于2025-09-10 09:29:36
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Microwave dual-mode resonators for coherent spin-photon coupling
摘要： We implement superconducting Yttrium barium copper oxide planar resonators with two fundamental modes for circuit quantum electrodynamics experiments. We first demonstrate good tunability in the resonant microwave frequencies and in their interplay, as emerges from the dependence of the transmission spectra on the device geometry. We then investigate the magnetic coupling of the resonant modes with bulk samples of 2,2-diphenyl-1-picrylhydrazyl organic radical spins. The transmission spectroscopy performed at low temperature shows that the coherent spin-photon coupling regime with the spin ensembles can be achieved by each of the resonator modes. The analysis of the results within the framework of the input-output formalism and by means of entropic measures demonstrates coherent mixing of the degrees of freedom corresponding to two remote spin ensembles and, with a suitable choice of the geometry, the approaching of a regime with spin-induced mixing of the two photon modes.
关键词： coherent spin-photon coupling,circuit quantum electrodynamics,Microwave dual-mode resonators,superconducting Yttrium barium copper oxide,2,2-diphenyl-1-picrylhydrazyl organic radical spins
更新于2025-09-10 09:29:36
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Low-temperature synthesis of hydride semiconductor YH3?δ using Pt capped Y films and its chemical thermodynamics analysis
摘要： To decrease the temperature at which metallic yttrium (Y) reacts with H2 to form the semiconductor trihydride phase, we employed Pt capping layers as catalysts, and compared the result with those obtained when employing Pd, Ni, or their co-capping layers. It was found that Pt capping with 5 nm thickness makes trihydride phase majority when hydrogenated at 27°C, and allows us to obtain the trihydride phase with approximately 100% molar concentration when hydrogenated at 150 – 200°C. Chemical thermodynamics analysis of the experimental results reveals that both the enthalpy and entropy differences between pure states of trihydride phase and dyhydride phase with hydrogen vapor show monotonic hydrogenation temperature dependencies with their sign inversions at approximately the same temperature around 150°C, suggesting a particular thermodynamic mechanism specific to the hydrogen – yttrium system.
关键词： Platinum,Electron beam evaporation,Yttrium dihydride,Enthalpy,Yttrium trihydride,Yttrium,Entropy,Gibbs free energy
更新于2025-09-09 09:28:46
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Ultrafast Multilevel Switching in Au/YIG/n-Si RRAM
摘要： Resistive random access memory (RRAM) with ultrafast and multilevel switching is extremely promising for next-generation nonvolatile memory. Here, ultrafast unipolar resistive switchings (≈540 ps) with high off/on resistance ratio (≈104) are obtained in yttrium iron garnet Y3Fe5O12 (YIG)-based resistive memory on n-Si substrate. The sub-nanosecond operation is also successfully performed up to 85 °C with an off/on resistance ratio of ≈103. In addition, by using different compliance currents for the set process, five discrete resistance levels with ultrafast switchings among them are achieved and the multilevel states show reliable retention (>104 s). The large, stable, reproducible, and reliable switching behaviors of the Au/YIG/n-Si RRAM cell shows its great potential for ultrafast multilevel memory applications.
关键词： yttrium iron garnet (YIG),unipolar resistance switching,multistates,fast switching
更新于2025-09-09 09:28:46
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Role of water in the sol-gel synthesis of yttrium monosilicate
摘要： Yttrium monosilicate (YMS) is a candidate environmental barrier coating material.It is a line compound, and its synthesis requires strict stoichiometric control of the starting materials. In this work, YMS was synthesised by the sol-gel method. Yttrium oxide and tetraethyl orthosilicate (TEOS) were used as precursors. The ratio of water to ethanol was varied to study the role of water in the formation of phase-pureYMS. The formation of secondary phases during synthesis was attributed to the complex interaction of TEOS with water in the presence of ethanol. It was seen that water and ethanol play a significant role in aqueous sol-gel processes involving silica than merely being present as solvents. The results are helpful in identifying the suitable sol-gel parameters for the synthesis of phase-pure yttrium monosilicate.
关键词： Environmental barrier coatings (EBC),Sol-gel synthesis,yttrium monosilicate (YMS)
更新于2025-09-09 09:28:46