Change from La2Ti2O7 to LaTiO3 induced by Li2CO3 addition: Higher local symmetry and particle uniformity achieved an efficient Mn4+ activated far red phosphor for agricultural cultivation

In this paper, a synthesized material change from perovskite-layer-structured La2Ti2O7 to perovskite type LaTiO3 induced by Li2CO3 addition was observed. The [TiO6] octahedral site symmetry and particle uniformity showed an obvious variation with the change from La2Ti2O7 to LaTiO3. A broadband far-red emission from 670 to 780 nm emerged when Mn4+, Li+ ions were co-doped. Furthermore, (Mn4+, Li+) co-doped LaTiO3 phosphor can be effectively excited by near-UV and blue lights, which is suitable for combining with commercial InGaN LED chips. The LaTiO3:0.4%Mn4+, 150%Li+ phosphor exhibited a high quantum efficiency of 71.1% and a good thermal stability with emission intensity retained 65% at 423 K. Finally, a LED device was fabricated with the LaTiO3:0.4%Mn4+, 150%Li+ phosphor, which matches well with the absorption of photochrome of PFR and shows a good potential for use in agricultural cultivation fields.