Synthesis and properties of submicron range CaSO4:Eu particles

CaSO4:Eu with particle size in submicron range was synthesized. Radiation induced Eu3+↔Eu2+ conversion as well as thermal conversion was studied. The samples showed thermal conversion above 400 °C. However, no radiation induced conversion in submicron range particles was observed. Particles heated above 400 °C coalesce and when heated at 925 °C bigger particles of 20 μm size were formed. Optical microscopy of these particles reveals red inclusion of about 5 μm inside CaSO4 particle. It is speculated that the red inclusion is CaS:Eu2+.