Upconversion luminescence and optical thermometry of Gd3BWO9: Yb3+, Er3+ phosphors

Rare earth upconversion (UC) luminescent materials have important application prospect in the field of optical thermometry due to the unique fluorescence properties. To search for new and efficient UC luminescent materials for optical temperature measurement, a series of Gd3BWO9: Yb3+, Er3+ UC phosphors were prepared through a high temperature solid-state reaction process. X-ray diffraction data show that all of the Gd3BWO9: Yb3+, Er3+ phosphors have pure Gd3BWO9 crystal phase. Under the excitation of 980 ​nm pump laser, all of the Gd3BWO9: Yb3+, Er3+ phosphors exhibit bright green emission at 522 ​nm and 543 ​nm. The UC luminescence mechanism and energy transfer (ET) processes were revealed by studying the power dependency of the UC emission intensities, and the green emission lifetimes of 4S3/2-2H15/2 were also measured to prove the existence of ET between Yb3+ and Er3+ ions. Moreover, the optical thermometry performance of Gd3BWO9: 0.20 ​Yb3+, 0.02 Er3+ was investigated by using fluorescence intensity ratio techniques. At 303 ​K, the relative sensitivity of phosphor is 0.94% K−1. The results manifest that Yb3+- Er3+ co-doped Gd3BWO9 phosphors can be used in optical temperature measurement.