Mi Xiaoyun

Synthesis of La3+ and Nd3+ co-doped yttria nanopowder for transparent ceramics by oxalate precipitation method

Abstract Polycrystalline Nd 3+ and La 3+ co-doped yttria nanopowder Nd 3+ :Y 1.90 La 0.10 O 3 for transparent ceramics was synthesized by co- precipitation method using oxalate acid as the precipitant and (NH 4 ) 2 SO 4 as the electrical stabilizer under ultrasonic radiation. Nanopowders calcined at different temperatures were characterized with thermal gravimetric-differential thermal analysis (TG/DTA), X-ray diffraction (XRD), transmitting electron microscopy (TEM), energy dispersive spectrometry (EDS) and spectral analysis techniques. The results indicated that nanopowders calcined at 1100 °C for 4 h were 40–70 nm in size with spherical morphology, the powder had the strongest emission peak centered at 1078 nm, corresponding to the transition of 4 F 3/2 → 4 I 11/2 of Nd 3+ ion. The highest optical transmittance of the ceramics sintered at 1500 °C for 13 h was about 48% in near IR waveband, and the sintered ceramics had a broad absorption bandwidth of about 12.6 nm at the laser diode (LD) pump wavelength of 808 nm.

Preparation and Study on Spectrum Characteristics of Sr0.99 Ce0.01 HfO3 Nanopowders

Abstract The Sr 0.99 Ce 0.01 HfO 3 nanopowders were synthesized by the co-precipitation method. The calcination temperature and time of the powders were 1200 °C and 2 h, respectively. The powder size of Sr 0.99 Ce 0.01 HfO 3 nanopowders was 15 × 30 nm. There were two excitation bands in the excitation spectra of the Sr 0.99 Ce 0.01 HfO 3 nanopowders, which peaking at 216 and 309 nm, respectively. There were two emission bands in the emission spectra excited by the 220 nm light, which peaking at 398 and 467 nm. And they were corresponding to the 5d→ 2 F 5/2 and the 5d→ 2 F 7/2 transitions of Ce 3+ ions. But there was only one emission band in the emission spectrum excited by the 309 nm light which peaking at 392 nm.

Preparation and Characterization Upconversion Luminescence Material of Yttrium Aluminate Doped with Rare Earth

Abstract Low phonon energy yttrium aluminate was adopted as matrix and the upconversion materials yttrium aluminate co-doped with Yb3+ and Er3+ was synthesized by solid-state reaction method. The X-ray diffraction spectra and the upconversion emission spectra of various samples were measured and the effect of Er3+ concentration, sensitization, fluxing agent and calcining temperature on the luminescence properties was studied. Research results showed that the sample could emit green light at 543 and 570 nm when excited 980 nm laser; the optimum concentration of Er3+ should be 1.0%; sensitization of Yb3+ could enhance luminescent effects of Er3+ obviously; the optimum content of F3BO3 fluxing agent should be 8% and the optimum calcining temperature should be 1500 °C.