Luminescence of Ce³⁺ in Y₂SiO₅ Nanocrystals: Role of Crystal Structure and Crystal Size

Abstract

Here, we report the role of crystal structure and crystal size on the photoluminescence properties of Ce³⁺ ions in Y₂SiO₅ nanocrystals. The emission at 430 nm (5d¹ → 4f¹) and lifetime of the excited state of Ce³⁺ ion doped Y₂SiO₅ nanocrystals are found to be sensitive to the crystal structure, crystal size, and dopant concentration. It is found that the overall lifetime 〈τ〉 of 0.5 mol % Ce doped Y₂SiO₅ nanocrystals are 8.78 and 3.45 ns for 1000 and 1100 °C heat-treated samples with the same crystal structure (X₁−Y₂SiO₅ phase), respectively. However, a significant increase in the overall lifetime (35.21 ns) is observed for the 1300 °C annealed 0.5 mol % Ce doped Y₂SiO₅ sample having a different crystal structure (X₂−Y₂SiO₅ phase). We found that the decay kinetic is biexponential. It is explained that the fast component arises due to sequential hole−electron capture on the luminescent ions and the slow component arises from isolated ions. Our analysis suggests that modifications of radiative and nonraditive relaxation mechanisms are due to local symmetry structure of the host lattice and crystal size, respectively.