A closer look at the defects and luminescence of nanocrystalline fluorides synthesized via ionic liquids: the case of Ce3+-doped BaF2

摘要: Phase pure BaF2 doped with Ce3+ (0.1%) nanocrystals are synthesized using an ionic liquid (IL) ([C4mim][BF4]) assisted solvothermal method where the IL is not only used as a reaction medium and capping agent, but also partner. Subsequently, upon calcining as-prepared at various temperatures (200, 400, 600 800 °C), athough crystal phase remains same, however, significant change in lattice strain morphology observed. Tensile appears calcined up to 400 °C, reversal of strain, i.e. compressive takes place when calcination performed °C onwards. Nanoflakes obtained until °C. However on beyond, drastic modification Layer or step-like structures appear due secondary nucleation nanoparticles. Meanwhile, photoluminescence (PL) intensity ions gradually decreases temperature finally vanishes °C/800 To investigate reasons for quenching PL intensity, thermally stimulated luminescence (TSL) exoelectron emission (TSEE) measurements performed. The TSL TSEE results indicate that addition domination deeper electron traps high-temperature shift glow peaks both some new types defects like F vacancies (F-centers) can be present, especially sample. conditions leading nanoparticles analyzed discussed.