Structure-composition-luminescence correlations in Sr2.5−3x/2Ba0.5SmxAl1−yInyO4F (0.001≤x, y≤0.1) oxyfluorides

► Strong and well-resolved emitting peaks are monitored in Sm3+-doped oxyfluoride phosphors. ► Diverse excitation and emission spectra of the oxyfluoride phosphors originated from Sm3+ activator and the defect-induced self-activation were clearly monitored. ► Oxyfluoride phosphors could be quite effective to prepare white-emitting light for (near)-UV LED applications.