Synthesis, Luminescence and Energy Transfer Properties of Ce³⁺/Mn²⁺ Co-Doped Calcium Carbodiimide Phosphors

Abstract

Ce3+-doped and Ce3+/Mn2+ co-doped calcium carbodiimide (CaCN2) phosphors were synthesized from doped calcium carbonate and carbon nitride by a solid-state reaction at 700 °C under flowing NH3 using a very short reaction time (1 h). The samples were characterized by powder X-ray diffraction, scanning electron microscopy and their diffuse reflectance and luminescence properties were investigated. Single-doped CaCN2:Ce3+ exhibits a blue emission under near-ultraviolet activation (386 nm) corresponding to the 5d1 → 2F5/2 and 5d1 → 2F7/2 transitions of Ce3+. Maximum emission is obtained at temperatures lower than 150 K and then progressively decreases up to 387 K, with an 80% drop in the emission at room temperature. Efficient energy transfers from Ce3+ to Mn2+ via a non-radiative dipole–dipole mechanism are evidenced for the co-doped samples, leading to various colored phosphors under near-ultraviolet activation (386 nm). The emission color of the obtained phosphors can be modulated from blue to red through a shade of white depending on the sensitizer/activator ratio.

Keywords

• carbodiimides
• phosphors
• co-doping
• carbon nitride
• energy transfer
• cerium