Investigation on temperature dependence of photoluminescence in Sr1.7Eu0.3MxCeO4.15+x/2 (M = Li+, Na+, K+, x = 0, 0.3) red phosphors

► For Li+-doing, Na+-doping or K+-doping, the different substitution mechanisms are proposed and confirmed. ► The Eu-O CT band shifts to longer wavelength by doping with monovalent ions, Li+, Na+, K+. ► We explain it via two factors, i.e., ionic charge and electronegativity value. We propose that the influencing of the former is larger than the latter. ► An obvious thermal quenching behaviors for all red emitting samples are observed, providing for a possible application of the materials in thermometry. ► The thermal quenching temperatures vary with the addition of monovalent ions, Li+, Na+, K+. ► We interpret it via the shift of the excited Eu-O charge transfer state, consisting of its energy and Δr. ► We put forward a possible way to change thermal quenching luminescence properties of fluorescence materials by adding appropriate impurity ions, which is important for their applications in luminescence or thermometry.