Crystal structure and luminescence properties of Lu3+ and Mg2+ incorporated silicate garnet [Ca3−(x+0.06)LuxCe0.06](Sc2−yMgy)Si3O12

► Charge balance plays an important role on the garnet structure formation. ► Bond lengths and polarizability affect the position of Ce3+ emission and excitation. ► Thermal quenching is analyzed based on configurational coordinate diagram. ► Our results provide an optimization method for phosphors used for white LEDs.