Cross relaxation of Sm³⁺ and energy transfer between Sm³⁺ and Eu³⁺ Ions in (Ca_0.97Sr_0.03)₃(VO₄)₂ phosphor host

An attempt was made to verify that the inhibition of Sm³⁺→Eu³⁺ energy transfer in (Ca_0.97Sr_0.03)_2.82(VO₄)₂:Sm³⁺,0.12Eu³⁺ phosphors at Sm³⁺ content levels of >0.06 mol can be ascribed to the cross-relaxation effect. The emission peak at around 951 nm attributed to the ⁶F_11/2→⁶H_5/2 transition of Sm³⁺, which should be barely detectable according to the energy-gap law, was observed in this work by exciting the ⁴K_11/2 state of Sm^{3 +}. The results indicate that cross-relaxation channels, which can depopulate the ⁴F_3/2 state of Sm³⁺, such as 1st Sm³⁺ (⁴F_3/2) + 2nd Sm³⁺ (⁶H_5/2)→1st Sm³⁺ (⁶F_11/2) + 2nd Sm³⁺ (⁶F_5/2) and 1st Sm³⁺ (⁴F_3/2) + 2nd Sm³⁺ (⁶H_5/2)→1st Sm³⁺ (⁶F_5/2) + 2nd Sm³⁺ (⁶F_11/2), may form and become efficient at an Sm³⁺ doping level of 0.06 mol. It was found that the 951-nm emission suffered from concentration quenching, which resulted from a dipole-dipole multipolar interaction.