Wydział Chemii

Damian Pasiński

Jerzy Sokolnicki

2019

Journal of Alloys and Compounds

786

808-816

10.1016/j.jallcom.2019.01.340

Naukowa

Angielski

Artykuł

Ca3Al2Ge3O12 phosphors, singly doped with Ce³⁺ and co-doped with Mn²⁺, were synthesized by the solid-state reaction in ammonia atmosphere at 1200 °C using Li2CO3 as a flux. The band gap energy of the host was determined to be 3.7 eV. In these phosphors, Ce³⁺ ions exclusively occupy the Ca²⁺ site, while Mn²⁺ ions occupy both the Ca²⁺ and Al³⁺ sites. Under 420 nm excitation, the Ce³⁺:Ca3Al2Ge3O12 phosphor emits bluish-green light from Ce³⁺ (470 nm) with a Stokes shift established at 2280 cm⁻¹. The Ce³⁺/Mn²⁺:Ca3Al2Ge3O12 phosphor excited at 420 nm emits orange light (580 nm) from Mn²⁺ in the Ca²⁺ site due to the Ce³⁺→Mn²⁺ energy transfer almost exclusively to this site. Ce³⁺ emission in the co-doped phosphor is very weak, even for relatively small concentrations (1%) of Mn²⁺. For Mn²⁺ concentration of 5% it disappears almost completely. Luminescence quantum yields of these phosphors amount to 24% and 20% in the case of Ce³⁺:Ca3Al2Ge3O12 and Ce³⁺/Mn²⁺:Ca3Al2Ge3O12, respectively. The critical distance for Ce³⁺ → Mn²⁺ energy transfer was calculated to be 6.2 Å and the efficiency of the energy transfer was estimated as 88%. These parameters suggest a non-uniform distribution of doped ions and the formation of Ce-Mn clusters.

Ca3Al2Ge3O12 garnet phosphor, melamine as reducing agent, photoluminescence, Ce/Mn energy transfer, Phosphor for w-LED, Cluster luminescence

https://doi.org/10.1016/j.jallcom.2019.01.340

http://www.elsevier.com