Single Crystal CaS:Eu and SrS:Eu Luminescent Particles Obtained by Solvothermal Synthesis

Single crystal CaS:Eu and SrS:Eu luminescent particles were synthesized via a solvothermal route at relatively low temperature (200°C). The as-obtained suspensions were strongly photoluminescent (PL), pointing at good Eu incorporation. The phosphors showed a broad PL emission band with an emission peak at 663 and 623 nm for CaS:Eu and SrS:Eu, respectively. The synthesis method meets the growing interest in small monodisperse particles. The composition and morphology of the particles was evaluated with transmission electron microscopy, scanning electron microscopy-energy dispersive X-ray and electron backscatter diffraction, particles were found to be mostly monocrystalline. X-ray diffraction showed a cubic structure with space group Fm3m. To control the growth of the crystallites, thioglycerol was added as capping agent, narrowing the size distribution and facilitating the growth of the single crystals.