Cationic pair substitution in LaAlO3:Mn4+ for octahedral-tilting-dependent zero-phonon line

Novel La1-xBaxAl1-xTixO3:0.001Mn4+ (LBAT:0.001Mn4+, x=0-0.2) and La1-yYyAl1-yGayO3:0.001Mn4+ (LYAG:0.001Mn4+, y=0-0.2) samples were successfully synthesized through a high-temperature solid-state reaction, and tunable ZPL of Mn4+ was found by cationic pair substitution of Ba2+-Ti4+ and Y3+-Ga3+ for
La3+-Al3+ in LaAlO3:Mn4+. The ZPL intensity is related to the local symmetry around Mn4+ and the ZPL energy corresponds to the Mn-O bond distance and the O-Mn-O bond distortion. Through co-doping Ba2+-Ti4+, the ZPL at 710 nm is enhanced and the intensity increases continuously with increasing the x value, due to the local symmetric degree of Mn4+ decreases slowly. However, the Y3+-Ga3+ co-doping induces linear and quick increase of the intensity of ZPL at 704 nm with increasing y value, due to the local symmetric degree of Mn4+ decreases quickly. The octahedral tilting distortion is very important for the local symmetry. Ba2+-Ti4+ co-doping reduces octahedral tilting distortion, but Y3+-Ga3+ co-doping induces a serious
octahedral tilting distortion. Consequently, the ZPL emission exhibits an octahedral-tilting dependent behavior. Mainly due to the larger distortion of O-Mn-O bond, the energy of ZPL for LYAG:0.001Mn4+ is higher than that for LBAT:0.001Mn4+. The outcomes of this work provide a promising way to regulate
the ZPL intensity and energy by tuning the local structure around Mn4+, and they may have wide implication for Mn4+-doped phosphors and solid state lighting.