ZHONG, J.; RSC Adv. 6 (2016) 89, 86285-86296, http://dx.

Nitrogen-doped carbon dots with multi-state visible absorption and full-color blue/yellow/red emissions are synthesized, and show potential applications in solid-state-lighting.

Due to the color centers induced by Na/K volatilization and Sm-doping, Sm-doped KNN transparent ceramics exhibit photochromism and reversible modulations of transmittance/luminescence intensities.

Yb(3+)/Er(3+)/Cr(3+) triply doped transparent bulk glass ceramic containing orthorhombic YF3 and cubic Ga2O3 nanocrystals was fabricated by a melt-quenching route to explore its possible application in optical thermometry with high spatial and temperature resolution. It was experimentally observed that Yb(3+)/Er(3+) ions incorporated into the precipitated YF3 nanophase, while Cr(3+) ions partitioned into the crystallized Ga2O3 nanophase after glass crystallization. Importantly, such spatial isolation strategy efficiently suppressed adverse energy transfer among different active ions. As a consequence, intense green anti-Stokes luminescence originated from Er(3+): (2)H11/2,(4)S3/2 → (4)I15/2 transitions, and deep-red Stokes luminescence transitions assigned to Cr(3+): (2)E → (4)A2 radiation were simultaneously realized. Impressively, the intermediate crystal-field environment for Cr(3+) in Ga2O3 made it possible for lifetime-based temperature sensing owing to the competition of radiation transitions from the thermally coupled Cr(3+) (2)E and (4)T2 excited states. In the meantime, the low-phonon-energy environment for Er(3+) in YF3 was beneficial for upconversion fluorescence intensity ratio-based temperature sensing via thermal population between the (2)H11/2 state and (4)S3/2 state. The Boltzmann distribution theory and the two-level kinetic model were adopted to interpret these temperature-dependent luminescence of Er(3+) and Cr(3+), respectively, which gave the highest temperature sensitivities of 0.25% K(-1) at 514 K for Er(3+) and 0.59% K(-1) at 386 K for Cr(3+).

A non-rare-earth doped Mn4+:Y3Al5O12red phosphor and the related glass–ceramics were fabricated to explore their application in white light-emitting diodes.

No abstract

A detailed nondestructive analytical method for quantitative food analysis was established by using a selffabricated NIR-LED light source combined with Mg 3 Ga 2 GeO 8 (MGGO) phosphor and a blue LED chip in one package, which can be integrated into smartphones. The phosphor of MGGO:Cr 3+ exhibits ultra-broadband NIR emission in the range of 650−1200 nm, which matches well with the overtones of molecular vibrations (e.g., O−H, C−H, and N−H) presented in food composition. The detailed crystal structure of MGGO was investigated by powder XRD Rietveld refinements, HRTEM images, and the corresponding SAED. Luminescence properties based on different Cr 3+ ions positions were investigated according to Gaussian peak fitting. Owing to the NIR response to organic elements, the working curves between absorbance and water content as well as sugar degree of pears and bananas were plotted. Then the reliability and veracity of the nondestructive analytical method were evaluated (R 2 = 0.9988). All the results suggest that the ultra-broadband NIR emission of MGGO:Cr 3+ phosphor has potential application as light sources integrated into smartphones for nondestructive food analysis.

Molecular composites comprising poly(p-sulfophenylene terephthalamide) (sPPTA), a sulfonated polyaramid rigidrod polyelectrolyte, and flexible-chain poly(vinyl alcohol) (PVA) were prepared by a green and easy-to-scale-up water casting method. Influence of sPPTA on the microstructure and properties of the molecular composites was systematically investigated. Fourier transform infrared spectroscopy confirms the existence of hydrogen bonding between sPPTA and PVA. Wide-angle X-ray diffraction patterns do not show the characteristic of neat sPPTA crystalline aggregates in the composites even when the sPPTA content is as high as 33 wt %, suggesting that the strong interaction between sPPTA and PVA prevents the self-aggregation of sPPTA and leads to the formation of PVA/sPPTA complexes inside the composites. Transmission electron microscopy shows that sPPTA has good compatibility with PVA, and nanoscale fibril-like supramolecular assemblies dispersing uniformly in the composites become observable with the increase of sPPTA content. Moreover, the PVA/sPPTA complexes have a strong effect on the melt point, crystallinity, mechanical properties, and thermal stability of PVA. The PVA/sPPTA composites exhibit both high strength and high ductility. When the content of sPPTA is 5 wt %, the PVA/sPPTA composite exhibits the best mechanical properties, with a tensile strength of 169 ± 13 MPa, which is 54% higher than that of neat PVA (110 ± 10 MPa). Surprisingly, the reinforcement factor is even superior to that of multiwalled carbon nanotubes, vapor grown carbon fibers, and nanodiamonds previously reported for the reinforcement of PVA nanocomposites. Moreover, the PVA/sPPTA molecular composites have a relatively low modulus but a much larger elongation at break than prefabricated nanocomposites, showing good ductility. The strong and tough PVA/sPPTA molecular composites can be potentially used as high performance membranes or fibers in the future.