Pyrophosphate Phosphor Solid Solution with High Quantum Efficiency and Thermal Stability for Efficient LED Lighting.

Phosphors with high quantum efficiency and thermal stability are greatly desired for lighting industries. Based on the design strategy of solid solution, a series of deep-blue-emitting phosphors (Sr0.99-xBax)2P2O7:0.02Eu2+ (SBxPE x = 0-0.5) are developed. Upon excitation at 350 nm, the optimized SB0.3PE phosphor shows a relatively narrow full width at half maximum (FWHM = 32.7 nm) peaking at 420 nm, which matches well with the plant absorption in blue region. Moreover, this phosphor exhibits obvious enhancement of internal quantum efficiency (IQE) (from 74% to 100%) and thermal stability (from 88% to 108% of peak intensity and from 99% to 124% of integrated area intensity at 150°C) compared with the pristine one. The white LED devices using SB0.3PE as deep-blue-emitting component show good electronic properties, indicating that SB0.3PE is promising to be used in plant growth lighting, white LEDs, and other photoelectric applications.

Improved luminescence and energy-transfer properties of Ca14Al10Zn6O35:Ti4+,Mn4+ deep-red-emitting phosphors with high brightness for light-emitting diode (LED) plant-growth lighting.

For plant-growth lighting, novel deep-red emission phosphors with high brightness were obtained by co-doping Ti4+ and Mn4+ into a Ca14Al10Zn6O35 substrate through a conventional solid-state reaction strategy. The nominal Ca14-(x+y)/2Al10-x-yZn6O35:xTi4+,yMn4+ (CAZO:Ti4+,Mn4+) phosphors could be excited by both near-ultraviolet (NUV) and blue-light-emitting diode (LED) chips efficiently and exhibited a strong deep-red emission band ranging from 650 nm to 750 nm, which should be the result of the 2E → 4A2 transition inside the [MnO6]8- octahedral. Multiple energy transfer from Ti4+ to Mn4+ was detected in this CAZO; whereby Ti4+ and Mn4+ phosphors were verified to be a result of the dipole-dipole interaction under excitation at 270 nm. LED plant-growth lights were fabricated using the as-prepared nominal Ca13.825Al9.65Zn6O35:0.15Mn4+,0.2Ti4+,0.005H3BO3 (CAZO:Mn4+,Ti4+,H3BO3) phosphors pumped by a 460 nm blue-chip; this luminaire could be used to greatly promote the cultivation of succulent plants. Combined with the attractive thermal stability as well as high quantum efficiency (QE) of this phosphor, it was demonstrated that these novel phosphors may be candidate deep-red luminescent materials for LED plant lighting.

A Short Review on Photocatalytic Degradation of Formaldehyde.

Nowadays, it is a great challenge to eliminate toxic and harmful organic pollutants from air and water. This paper reviews the role of TiO2 as a photocatalyst, light source and photoreactor in the particular case of removal of formaldehyde using the photocatalytic reaction by titanium dioxide (TiO2) in aqueous and gaseous systems. The reaction mechanisms of the photocatalytic oxidation of gaseous formaldehyde are given. We also present a detailed review of published articles on photocatalytic degradation of formaldehyde by modified titanium dioxide doped with foreign species such as metal and non-metal components. We point out the most prospective developments of the photocatalyst compositions for the future potential commercial applications.

Low energy 4f-5d transitions in lanthanide doped CaLaSiN3 with low degree of cross-linking between SiN4 tetrahedra.

CaLaSiN3 samples doped with Eu, Yb, Sm, Ce and Pr have been prepared via solid-state reaction synthesis and the optical properties have been studied. Both Yb and Sm were only observed in the trivalent state due to the fact that their Ln(2+) ground states are located inside or very close to the conduction band of the CaLaSiN3 host lattice. Doping with Ce(3+) or Eu(2+) resulted in a very low energy Ce(3+) or Eu(2+) 4f-5d absorption band around 1.9 eV (650 nm) and 1.4 eV (885 nm), respectively. The Ce(3+) 5d-4f emission appeared to be quenched, just as the Eu(2+) 5d-4f emission, which can be explained as the result of auto-ionization.