Robust color purity of reddish-orange emission from Sm^(3+)-activated La10W22O81 biocompatible microphosphors for solid state lighting and anticancer applications

We synthesized reddish-orange luminescent La_(10)W_(22)O_(81)(LWO):Sm^(3+)microphosphors by hydrothermalassisted solid-state reaction.X-ray diffraction analysis reveals that all the studied phosphors crystallize in an orthorhombic structure in the Pbcn space group(60),Field emission scanning electron microscopy indicates that the LWO:1.5 mol% Sm^(3+)phosphor displays a smooth-surfaced hexagonal rod-like shape,with a closed shape at both ends,and high-resolution transmission electron microscopy demonstrates a robust crystalline structure.The chemical composition and valence states of the phosphor were investigated using X-ray photoelectron spectroscopy.At 403 nm excitation,LWO:1.5 mol% Sm3+exhibits maximum intensity with the strongest band at 596 nm(^(4)G_(5/2)→^(6)H_(7/2)) in the reddish-orange region.The intensity of Sm^(3+) emission decreases beyond 1.5 mol% owing to concentration quenching regulated by dipole-quadrupole interaction between Sm^(3+)ions.The optimized microphosphor LWO:1.5 mol% Sm^(3+)exhibits color coordinates(0.5760,0.4207),which is close to that of the Amber LED-NSPAR 70 BS(0.570,0.420),displaying the highest color purity of 99.2% and correlated color temperature of 1694 K.In addition,both breast cancer cells MCF-7 and normal lung fibroblasts WI-38 were tested for toxicity with the optimized microphosphor.It is found that the LWO:1.5 Sm^(3+)microphosphor is extremely toxic to cancer cells,but not to normal cells.Based on these results,LWO:Sm^(3+)microphosphor can serve as a biomedical candidate for the treatment of cancer,as well as a potential multicolor emitting material for w-LEDs.

Massively parallel direct writing of nanoapertures using multi-optical probes and super-resolution near-fields

Laser direct-writing enables micro and nanoscale patterning,and is thus widely used for cutting-edge research and industrial applications.Various nanolithography methods,such as near-field,plasmonic,and scanning-probe lithography,are gaining increasing attention because they enable fabrication of high-resolution nanopatterns that are much smaller than the wavelength of light.However,conventional methods are limited by low throughput and scalability,and tend to use electron beams or focused-ion beams to create nanostructures.In this study,we developed a procedure for massively parallel direct writing of nanoapertures using a multi-optical probe system and superresolution near-fields.A glass micro-Fresnel zone plate array,which is an ultra-precision far-field optical system,was designed and fabricated as the multi-optical probe system.As a chalcogenide phase-change material(PCM),multiple layers of Sb_(65)Se_(35) were used to generate the super-resolution near-field effect.A nanoaperture was fabricated through direct laser writing on a large-area(200×200mm^(2))multi-layered PCM.A photoresist nanopattern was fabricated on an 8-inch wafer via near-field nanolithography using the developed nanoaperture and an i-line commercial exposure system.Unlike other methods,this technique allows high-throughput large-area nanolithography and overcomes the gap-control issue between the probe array and the patterning surface.