The role of surface related quenching in the single band ratiometric approach based on excited state absorption processes in Nd3+ doped phosphors

Abstract One of the newest approaches to ratiometric luminescence thermometry, namely, the single band ratiometric (SBR) approach, that involves excited state absorption, has been intensively investigated in recent years due to its unique features. The development of the highly sensitive luminescent temperature probe based on this approach is possible only when the physical processes and material parameter of the phosphors that affects the probability of the excited state absorption will be determined. Therefore, in this work, for the first time, the influence of phosphor size and the role of surface quenching processes on the sensitivity of this type of luminescent thermometers are investigated and discussed. It has been shown that surface related depopulation processes of the intermediate 4I11/2 energy levels strongly affect the intensity of the 4F3/2→4IJ emission excited by excited state absorption. It leads to a reduction of the sensitivity of this type of luminescent thermometers and a narrowing of its usable temperature range. As a consequence, it has been shown that the maximum relative sensitivity of YAG:Nd-based thermometer changes as follows 2.38 %/oC, 8.46 %/oC and 9.51 %/oC for a phosphor in the form of nanocrystals, microcrystals and ceramics, respectively.