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Yellow emitting Sm 3+-doped NaBa 1-x BO 3(0.01 ≤ x ≤ 0.13) phosphors were synthesized by conventional solid state reaction method. The phase structure and luminescence properties of the as-prepared phosphors were investigated. These phosphors can be effectively excited by 403 nm near-ultraviolet light and feature a satisfactory yellow performance. The emission peaks are observed at 560 nm, 603 nm and 650 nm, originating from the transitions of 4G5∕2→6H5∕2, 4G5∕2→6H7∕2 and 4G5∕2→6H9∕2 respectively. Investigation of Sm 3+ concentration-dependent emission spectra indicates that the NaBa 0.95 BO 3:0.05 Sm 3+ phosphor shows the strongest yellow emission intensity and exhibits the CIE value of x = 0.4760 and y = 0.5090. Through the theoretical calculation, a high color purity of 96.0% was determined for the NaBaBO 3: Sm 3+ phosphor, and the color purity of NaBaBO 3: Sm 3+ is much higher than that of the commercial yellow phosphor YAG : Ce 3+. This work is highly relevant to the development of a new type of potential down-conversion (DC) yellow phosphor for near ultraviolet white or yellow light-emitting diodes (LEDs).

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In this paper, using the surface plasmon and Fabry–Pérot (FP) cavity, the design of a symmetric silicon grating absorber is proposed. The time-domain finite difference method is used for simulation calculations. The basic unit structure is a dielectric grating composed of silicon dioxide, metal and silicon. Through the adjustment of geometric parameters, we have achieved the best of the symmetric silicon grating absorber. A narrowband absorption peak with an absorption rate greater than 99% is generated in the 3000–5000 nm optical band, and the wavelength of the absorption peak is λ = 3750 nm. The physical absorption mechanism is that silicon light generates surface plasmon waves under the interaction with incident light, and the electromagnetic field coupling of surface plasmon waves and light causes surface plasmon resonance, thereby exciting strong light response modulation. We also explore the influence of geometric parameters and polarization angle on the performance of silicon grating absorbers. Finally, we systematically study the refractive index sensitivity of these structures. These structures can be widely used in optical filtering, spectral sensing, gas detection and other fields.

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A novel white-light-emitting Sr 3 B 2 O 6: Dy 3+ phosphor was prepared by solid-state reactions and its luminescence properties were investigated. The excitation spectrum of obtained phosphor monitored at 479 nm covers a very broad spectral region from 320 nm to 460 nm with peaks at 323, 349, 363, 386, 427 and 456 nm. Under excitation at 349 nm, the phosphor exhibits a blue emission centered at 479 nm and a yellow emission centered at 574 nm. The optimal doping concentration of Dy 3+ is obtained to be 7 mol%, and the concentration quenching is observed when the concentration of Dy 3+ exceeds 7 mol%. This concentration quenching is due to the enhanced energy exchange among Dy 3+ ions. The CIE chromaticity coordinate (0.289, 0.302) of Sr 3-0.07 B 2 O 6:0.07 Dy 3+ located in the white-light region can be achieved. Theoretical calculations of electronic properties for Sr 3 B 2 O 6: Dy 3+ phosphor in the framework of the density functional theory (DFT) were carried out. Our results suggest that the Sr 3 B 2 O 6: Dy 3+ phosphor is a promising single-component white-light-emitting material.

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