A single-host white-light-emitting phosphor BaSrMg(PO4)2 : EU2+ was prepared by high temperature solid-state reaction method, and the luminescence characteristics and XRD pattern were investigated. The results showthat BaSrMg(PO4)2 phase was obtained by sintering at 1 200 degrees C for 3 hours. BaSrMg(PO4)2 = Eu2+ phosphor exhibits two main emission bands peaking at 424 and 585 nm, respectively. The emission band peaking at 424 nm is attributed to the 4f 6 5d1 --> 4f7 transition of Eu2+ substituting Sr2+, while the emission band peaking at 585 nm originates from the 4f 6 5d1 --> 4f7 transition of Eu2+ replacing Ba2+ in host lattice. The excitation spectra of the two emission peaks are range from 250 to 400 nm and both peaking at 360 nm. The effect of the proportion of Ba and Sr, and the Eu2+ doping concentration on the emission intensity were discussed in detail. Different chromaticity coordinates were obtained for each phosphor, that is, the chromaticity coordinates of the designed phosphor is tunable for the white-emitting LED or for special purpose. Quantum efficiency was also examined for the phosphors with different Eu2+ doping concentration, and concentration quenching took place obviously when Eu2+ doping concentration was lager than 6% in mole ratio. The obtained phosphor BaSrMg(PO4)2 : Eu2+ can be excited by near ultraviolet radiation effectively and emit full color lighting, which is a promising single-host white-light-emitting phosphor for white LED.
In order to solve the difficulties faced by aircraft fuel tank failure inspection, this paper designs a multi-backbones continuous robot based on a push-pull structure. In order to explain the deformation characteristics of the robot from a mechanical point of view, the Newton-Euler method is used to determine the tension of the robot's flexible backbones, the gravity of the mechanism components, and the external environmental forces and moments are analyzed and the robot statics balance equation is established. Secondly, the particle swarm optimization algorithm is used to solve the nonlinear equations. Finally, the homogeneous transformation matrix is used to solve the robot deformation contour based on the bending angle of the unit segment.
Silver nanowires, which have high optoelectronic properties, have the potential to supersede indium tin oxide in the field of electrocatalysis, stretchable electronic, and solar cells. Herein, four mainstream experimental methods, including Mayer-rod coating, spin coating, spray coating, and vacuum filtration methods, are employed to fabricate transparent conductive films based on the same silver nanowires to clarify the significance of preparation methods on the performance of the films. The surface morphology, conductive property, uniformity, and flexible stability of these four Ag NW-based films, are analyzed and compared to explore the advantages of these methods. The transparent conductive films produced by the vacuum filtration method have the most outstanding performance in terms of surface roughness and uniformity, benefitting from the stronger welding of NW-NW junctions after the press procedure. However, limited by the size of the membrane and the vacuum degree of the equipment, the small-size Ag films used in precious devices are appropriate to obtain through this method. Similarly, the spin coating method is suited to prepare Ag NWs films with small sizes, which shows excellent stability after the bending test. In comparison, much larger-size films could be obtained through Mayer-rod coating and spray coating methods. The pull-down speed and force among the Mayer-rod coating process, as well as the spray distance and traveling speed among the spray coating process, are essential to the uniformity of Ag NW films. After being treated with NaBH4 and polymethyl methacrylate (PMMA), the obtained Ag NW/PMMA films show great potential in the field of film defogging due to the Joule heating effect. Taken together, based on the advantages of each preparation method, the Ag NW-based films with desired size and performances are easier to prepare, meeting the requirements of different application fields.
Hybrid calcium carbonate (CaCO3)/poly(styrene sulfonate) (PSS) particle, as a template, was synthesized using colloidal crystallization with the presence of nitrate tetrahydrate (Ca(NO3)2•4H2O), sodium carbonate (Na2CO3) and PSS. Microcapsule was prepared by template-assisted layer-by-layer (LbL) technology in solutions of two oppositely charged polyelectrolytes, poly(styrenesulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) alternately, followed by dissolving the template with disodium ethylenediaminetetraacetate (EDTA). The release behavior of rhodamine B (RhB) from the microcapsules was examined and the rates of release at different pH were studied.
Realizing dynamic regulation of specific optical components while being easy to integrate with photonic circuits will have a revolutionary impact on tunable laser sources, active filters, and all-optical switching/integration. Here, we demonstrate a temperature tunable Ga-doped ZnO microresonator with a conductivity of ∼1.75 S/cm controlled by the injection current and realize point-to-point heating. The shift in the resonant wavelength with a tuning range of 2 nm for TE66 mode is achieved by the effect of current-induced temperature rising on the refractive index of the microresonator crystal, namely, the thermo-optic effect. Meanwhile, the thermo-optic coefficient of 16.7 × 10−4/K around the bandgap energy of ZnO is also obtained. This operating mode of electronically controlled temperature establishes a solid foundation for the practicality and integration of tunable lasers.
Ultrathin Cu nanowires with diameters as thin as 7 nm are synthesized through introducing Au nanoparticles as catalytic sites and diameter controllers.
Plasmonic metal nanostructures are promising for chemical and biological sensor applications due to their high spectral sensitivity, defined as the relative shift in resonance wavelength with respect to the refractive index changes of the surroundings. In this work, the refractive index sensitivity (RI sensitivity) of one kind of core-shell nanostructure was studied, in which the gold nanobipyramid (AuBP) core was sheltered by the Au-Ag alloy shell. We investigated the dependence of the RI sensitivity and the figure of merit (FOM) of the localized surface plasmon resonance (LSPR) on the geometry and the composition of the nanostructures. Theoretical consideration on the LSPR revealed that the RI sensitivity of the nanostructures is determined by the bulk plasma wavelength, dielectric properties of the alloy and the geometrical parameters. To quantitatively explore the dependence of the RI sensitivity on the metal compositions and the aspect ratios of the nanostructures, the frequency-related dielectric properties of the alloy were calculated using the Drude-critical points model (DCPM). Then the calculated dielectric data were applied in the finite difference time domain (FDTD) solutions to simulate the optical spectra of the alloy nanostructures with various Ag concentrations. Experimentally, a series of fabrication processes were also carried out for the growth of a homogeneous Au-Ag alloy nanoshell on the surface of AuBPs using a wet-chemical method. The measured RI sensitivities agree well with the values predicted from FDTD simulations, indicating the availability, credibility and feasibility of the modelled dielectric data of the alloy. The DCPM and FDTD simulations can be combined to calculate the dielectric properties and forecast the sensitivity properties of the Au-Ag alloyed nanostructures with varying concentrations.
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