Towards ultra-sensitive multimodal luminescent thermometers enabled by high crystal field strength of Lu2CaMg2Ge3O12:Yb3+,Nd3+,Er3+ phosphors

An effective full-spectrum thermometer covering from the visible to NIR-II band was designed based on garnet Lu 2 CaMg 2 Ge 3 O 12 :Yb 3+ ,Er 3+ /Nd 3+ phosphors; meanwhile, Er 3+ ( 4 I 13/2 ) split into four Stark sublevels due to high crystal field strength.