Optical Thermometry Based on Up-Conversion Luminescence Behavior of Er3+ -Doped Transparent Sr2YbF7 Glass-Ceramics

Transparent novel glass-ceramics containing Sr2YbF7:Er3+ nanocrystals were successfully fabricated by melt-quenching technique. Their structural and up-conversion luminescent properties were systemically investigated by XRD, HRTEM, and a series of spectroscopy methods. The temperature-dependent up-conversion spectra prove that H-2(11/2) and S-4(3/2) levels of Er3+ are thermally coupled energy levels (TCEL). Consequently, the H-2(11/2) -> I-4(15/2) and S-4(3/2) -> I-4(15/2) emissions of Er3+ in Sr2YbF7:Er3+ glass-ceramics can be used as optical thermometry based on fluorescence intensity ratio (FIR) technique. Combined with low phonon energy and high thermal stability, Er3+ ions in Sr2YbF7 glass-ceramics present broad operating temperature range (300-500 K), large energy gap of TCEL (786 cm(-1)) and high theoretical maximum value of relative sensitivity (62.14 x 10(-4) K-1 at 560 K), which suggests that Sr2YbF7:Er3+ glass-ceramics may be excellent candidates for optical temperature sensors.