Crystal growth study of CaGa2S4 Co-doped with Ce3+ and Na+

We have examined the effects of co-doping of Ce3+ and Na+ in CaGa2S4. Differential thermal analysis and X-ray diffraction analysis were carried out on the compounds of Ca(1−x)Cex/2Nax/2Ga2S4 (0⩽x⩽1) to obtain the necessary information for their synthesis. It is shown that Ce3+ and Na+ can be simultaneously doped into CaGa2S4 up to about 30 mol% (x=0.6). The melting point was determined as a function of x. Photoluminescence (PL) was measured with these products, where the maximum intensity was found at 10 mol% (x=0.2). Single crystals of Ca(1−x)Cex/2Nax/2Ga2S4 (x=0.02 and 0.2) were grown from melt by the horizontal Bridgman method. Light absorption was measured near the fundamental absorption edge using a high quality part of the single crystals. Photoluminescence excitation (PLE) spectra were also measured using compounds of Ca(1−x)Cex/2Nax/2Ga2S4 with x=0.02, 0.2 and 0.5 and a Ce only-doped CaGa2S4:Ce+ (0.8 mol%).