Laser-heated pedestal growth of cerium doped calcium scandate crystal fibers

Ce3+ doped oxide materials are promising for optical emission in the green spectral range. The growth of CaSc2O4:Ce3+ single crystals is reported here for the first time. Laser heated pedestal growth (LHPG) proved to be suitable for this refractive material, if performed in nitrogen of 99.999% purity. If the oxygen content of the growth atmosphere is substantially larger, Ce4+ is formed, which shows no useful optical emission. If the oxygen content is substantially lower, severe evaporation of calcium impedes stable crystal growth. Thermodynamic equilibrium calculations allowed to describe evaporation of species and cerium dopant charging under different growth conditions. The evaporation could be investigated by quadrupole mass spectrometry of emanating gases and by chemical analysis of fibers with ICP-OES. The congruent melting point was confirmed by DTA at 2110°C. Photoluminescence spectrometry of fibers revealed the dependence of optical emission in the green spectral range on growth conditions. ► First single crystals of cerium doped calcium scandate. ► Optimized atmosphere (5N nitrogen) and growth parameters with respect to Ce3+ formation and fiber quality. ► Evaporation of Ca and Ce species confirmed with high temperature mass spectrometry. ► Deviations of composition can be explained with ICP-OES, DTA and Factsage calculation. ► Photoluminescence spectra reveal the dependence of optical emission in the green spectral range on growth conditions.