Multipath luminescent thermometry inCs3GdGe3O9:Yb3+, Er3+ phosphor

Nowadays, luminescent thermometry appeals the eyes of researchers more and more on account of the unique merits including non-invasive, fast response and relatively high sensitivity. However, most of reported up-conversion optical thermometric materials based on fluorescence intensity ratio (FIR) from thermal couple energy levels (TCELs) usually suffer from the overlap of two luminescence signals, leading to the deviation of the temperature readout. Herein, Cs3GdGe3O9:Yb3+,Er3+ phosphors were successfully synthesized. Multiple sharp peaks from green and red luminescence of Er3+ are observed. The emission signals even from the TCELs are well separated, enabling the accuracy of temperature detection to some extent. With the aid of the different thermo-responses of luminescence centered at 534, 559, 660 nm and their splitting peaks of Er3+, multi-mode optical thermometric techniques based on fluorescence decay time (4S3/2), FIR from TCELs, non-TCELs and their sub-energy levels in Cs3GdGe3O9:Yb3+,Er3+ upon single-beam light stimulation were designed. The resultant sample reveals excellent signal discernibility, eminent relative sensitivities, outstanding reversibility and glorious thermal resolution. Such results infer that Cs3GdGe3O9:Yb3+,Er3+ phosphors have the promising prospect in temperature monitoring fields.