Color tunability and temperature sensing in transparent Dy3+/Eu3+ co-doped oxyfluoride glass ceramics containing KGd2F7 nanocrystals

Transparent oxyfluoride glass-ceramics (GCs) containing KGd 2 F 7 nanocrystals co-doped with Dy 3+ and Eu 3+ were prepared and systematically studied in terms of their luminescence behavior, energy transfer (ET) mechanism, and ratiometric temperature-sensing performance. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the uniform precipitation of well-crystallized KGd 2 F 7 nanocrystals (~ 15.7 nm) within the glass matrix. By varying the Eu 3+ concentration, the emission color was continuously tuned from yellow to orange-red. Efficient Dy 3+ →Eu 3+ energy transfer via a quadrupole–quadrupole interaction was verified by emission spectra and decay analysis. The optimal sample exhibited an absolute sensitivity (S a ) of 0.372% K − 1 , a relative sensitivity (S r ) of 0.388% K − 1 , and excellent temperature resolution. These results indicate that the Dy 3+ /Eu 3+ co-doped KGd 2 F 7 GCs are promising candidates for multicolor displays and high-precision optical thermometry.