Phosphors Ba₂ LaTaO₆ :Mn⁴⁺ and its alkali metal charge compensation for plant growth illumination

A series of Mn⁴⁺ -doped and Mn⁴⁺ ,K⁺ -co-doped Ba₂ LaTaO₆ (BLT) double-perovskite phosphors was synthesized using a high-temperature solid-state reaction. The phase purity and luminescence properties were also studied. The optimum doping concentration of Mn⁴⁺ and K⁺ was obtained by investigating the photoluminescence excitation spectra and photoluminescence emission spectra. The comparison of BLT:Mn⁴⁺ phosphors with and without K⁺ ions shows that the photoluminescence intensity of K⁺ -doped phosphors was greatly enhanced. This is because there was a charge difference when Mn⁴⁺ ions were doped with Ta⁵⁺ ions in BLT. Mn⁴⁺ -K⁺ ion pairs were formed after doping K⁺ ions, which hinders the nonradiative energy transfer between Mn⁴⁺ ions. Therefore, the luminescence intensity, quantum yield, and thermal stability of phosphors were enhanced. The electroluminescence spectra of BLT:Mn⁴⁺ and BLT:Mn⁴⁺ ,K⁺ were measured. The spectra showed that the light emitted from the phosphors corresponded well with chlorophyll a and phytochrome P_R . The results show that the BLT:Mn⁴⁺ ,K⁺ phosphors had good luminescence properties and application prospects and are ideal materials for plant-illuminated red phosphors.