Quenching cooperative transitions by destroying Yb-clusters.

In our previous study, we have reported the cooperative luminescence of Yb-trimers and cooperatively sensitized Gd luminescence by Yb-tetramers in a doped CaF host. In this study, we experimentally observed an unusual luminescent phenomenon of Gd in CaF:Yb/Gd. Upon excitation with a 980 nm laser, the upconversion luminescence of Gd first increases and then decreases in the Gd concentration range of 0-0.

White upconversion luminescence in CaF2:Yb(3+)/Eu(3+) powders via the incorporation of Y(3+) ions.

White upconversion luminescence (UCL) was achieved under 980 nm excitation in the CaF2:Yb(3+)/Eu(3+) material using Y(3+) to adjust the luminescence performance. In this luminescent system, Yb(3+) not only plays the role of a sensitizer of Eu(3+), but also generates green fluorescence from Yb(3+) dimers (2-Yb(3+)) by cooperative transitions in the CaF2 matrix. One of the primary colors of green corresponds to the 2-Yb(3+) cooperative emission exactly.

[Near-infrared photoluminescence properties of natural sodalite activated with Mn and Fe transition metal ions doping].

Na8Al6Si6O24Cl2 : Mn and Na8Al6Si6O24Cl2 : Fe NIR phosphors were prepared by a solid-solid reaction at high temperature. Their crystal structures of fluorescent powder were investigated by using X-ray powder diffraction (XRD), and their NIR emission spectrum and excitation spectrum were measured at room temperature. The main emission peak of Mn5+ in the Na8Al6Si6O24Cl2 : Mn phosphor was observed at 1 200 nm in the NIR spectral region under 400 or 602 nm excitation, attributing to the 3A2-3T2 and 3A2-1E transitions of Mn5+ ions.

[Gd-doped natural thenardite: Eu photoluminescence properties of europium].

The authors prepared Na2SO4: Eu, Gd, and Na2Gd2 (SO4)4: Eu phosphors by heating, the mixed powder of GdF3, EuF3 and natural mirabilite with muffle furnace at 1 000 degrees C for 30 min and continually heating it with microwave at 750 degrees C for 10 min. With increasing the concentrations of Gd ion, the 610 nm emission intensity due to Eu3+ was strengthened. Gd3+ probably formed a bridge between substrate and the activator so that the energy is able to be transferred efficiently.