Up-conversion thermometric properties of nanorod-like K2Bi0.98−xEr0.02YbxNb5O15

Abstract A series of K 2 Bi 0.98−x Er 0.02 Yb x Nb 5 O 15 (KBN-x, 0≤x≤0.15) up-conversion nanoparticles (UCNPs) with different particle sizes have been prepared which exhibit a single phase tungsten bronze (TB) structure. It is found that synthesis temperature (T s ) acts an important factor to determine the particle size and nanorod-like particles are obtained for all samples as T s ≤1100 °C. Bright up-conversion (UC) green ( 2 H 11/2 / 4 S 3/2 → 4 I 15/2 ) and weak red ( 4 F 9/2 → 4 I 15/2 ) emissions are realized. Based on the fluorescence intensity ratio (FIR) of green emissions, temperature-dependent UC luminescence and thermometric properties of KBN-x UCNPs were investigated. We show that Yb 3+ -concentration and particle size both have important influence on the sensitivity of KBN-x system.