Solid state solutions of Ce-Tb-F and K-Ce-Tb-F: Synthesis, optical properties and energy transfer

The Ce-Tb-F and the K-Ce-Tb-F solid state solutions have been synthesized by a hydrothermal method without any additives. The crystalline phases of the solid state solutions were characterized by X-ray diffraction (XRD) technique and the results suggest that the solid state solutions crystalized in hexagonal phases then cubic phases with the molar ratio of Ce3+-Tb3+ decreasing. The particle morphologies and sizes of some representative samples were characterized by transmission electron microscopy (TEM) images and the results suggest that the two system solid state solution samples were nanocrystals yet the Ce3+ or the Tb3+ introduction had great effects on the morphologies and sizes of the nanocrystals. The Ce3+ presented different optical properties in sensitizing Tb3+ emissions. With the Tb3+ concentration increasing, the emission intensity firstly decreased, reached the minimum when the Tb3+ concentration was 70%, and then increased. The possible reasons were discussed in the manuscript. (C) 2016 Elsevier B.V. All rights reserved.