Optimization of synthesis and compositional parameters of magnesium germanate and fluoro-germanate thermographic phosphors

Various documented formulations of magnesium germanate and flouro-germanate were synthesized by conventional solid state method at various temperatures to find out optimal synthesis conditions for maximum luminescence intensity. Relative efficiency of luminescence intensity and thermal stability of luminescence of these formulations is then discussed with respect to the commercially available phosphor. Mg28Ge7.5O38F10:Mn4+ was found to be the most efficient when synthesized at 1150 °C in air and has a comparable efficiency with respect to commercial sample. Photoluminescence intensity with increasing temperature was measured till 500 °C; the samples showed persistent emission till 300 °C. Relatively, samples with MgF2 give stronger emission at high temperatures if added in proper ratio.