Synthesis of a new phosphor (LaPO 4 :Ce, Li, Mn) and kinetics study for thermal process of its precursor

•La0.9Ce0.05(LiMn)0.05PO4⋅0.92H2O was obtained via solid-state reaction at 60°C.•A green-yellow emitting phosphor, La0.9Ce0.05(LiMn)0.05PO4 was obtained from the precursor.•The spin-forbidden transition of Mn2+ seem to be released by Li+ co-doped.•The Eα was determined with two isoconversional iterative procedures.•Three methods were used to comparative study the mechanisms.