Crystalline phase effect on the up-conversion processes and white emission of Yb/Er/Tm:YSiO nanocrystals.

Yb3+,Er3+,Tm3+:Y2Si2O7 nanopowders were fabricated by a sol-gel method and then annealed at two different temperatures of 1050 °C and 1480 °C for 12 h to investigate the phase effect on the structural and optical properties. X-ray diffraction patterns (XRD) of all powders revealed that most of the peaks were in good harmony with the standard JCPDS cards of Y2Si2O7 (PDF #38-0223 and PDF #38-0440). SEM images of the powders were taken to examine the morphology and chemical composition of the powders.

Near-Infrared Free-Radical and Free-Radical-Promoted Cationic Photopolymerizations by In-Source Lighting Using Upconverting Glass.

A method is presented for the initiation of free-radical and free-radical-promoted cationic photopolymerizations by in-source lighting in the near-infrared (NIR) region using upconverting glass (UCG). This approach utilizes laser irradiation of UCG at 975 nm in the presence of fluorescein (FL) and pentamethyldiethylene triamine (PMDETA). FL excited by light emitted from the UCG undergoes electron-transfer reactions with PMDETA to form free radicals capable of initiating polymerization of methyl methacrylate.