Optical thermometry based on up-conversion luminescence behavior of Er3+-doped KYb2F7 nano-crystals in bulk glass ceramics

Er3+-doped transparent bulk glass ceramics (GC) containing KYb2F7 nano-crystals were fabricated by melt-quenching technique and subsequent thermal treatment. Their structural and up-conversion luminescent properties were systemically investigated. Optical spectroscopy analysis demonstrates the incorporation of Er3+ into the KYb2F7 crystalline lattice, resulting in highly enhanced up-conversion luminescence. The temperature sensing performance of KYb2F7:Er3+ were investigated by the fluorescence intensity ratio of the thermally coupled emitting levels (2H11/2 and 4S3/2). Due to low phonon energy and high thermal stability, Er3+ ions in KYb2F7 GC present large energy gap (844 cm−1) and high theoretical maximum value of relative sensitivity (45.40 × 10−4 K−1 at 590 K), suggesting that KYb2F7:Er3+ GC can be excellent candidates for optical temperature sensors.