| abstract |
A rare earth ceramic having a microcrystal phase buried in a glassy phase for the coversion of radiation in the near-infrared band from about 0.85 to 1.06 um into visible light. It comprises a mixture of lead fluoride PbF 2 , ytterbium oxide Yb 2 O 3 , at least one glass-forming oxide selected from the oxides of B, Si, P, Ge, Te, and at least one compound of a rare earth doping element chosen as a function of the desired emission color, i.e. n A compound containing thulium ions Tm 3 + for a blue emission mixture; n A compound containing erbium ions Er 3 + for a green emission mixture; n A compound containing holmium ions Ho 3 + for a green emission mixture; n A compound containing erbium ions Er 3 + for a red emission mixture, whereby the oxygen ions from the oxides are exclusively located in the glassy phase while ytterbium and the rare earth are exclusively located in the microcrystal phase. n The relative proportion of the glass-forming oxides to the ytterbium oxide and lead fluoride, the relative proportion of ytterbium oxide to the glass-forming oxides and lead fluoride and the relative proportion of doping rare earths in the form of oxides to the finished ceramic must lie within respective predetermined ranges. |