Passive temperature sensing using thermoluminescence: Laboratory tests using Li2B4O7:Cu,Ag, MgB4O7:Dy,Li and CaSO4:Ce,Tb

The objective of this work is to test three thermoluminescent (TL) materials, Li2B4O7:Cu,Ag (LBO), MgB4O7:Dy,Li (MBO) and CaSO4:Ce,Tb (CSO), as passive temperature sensors. Particles of these materials were subjected to two heating profiles: (a) a slow heating profile (2 h inside a muffle furnace) or (b) a fast heating profile (dropping them through a temperature chamber for ~1 s). The TL curves from these heated particles were recorded and compared to the TL from control samples, which were not exposed to the temperature profile. A simple TL model (first order TL peaks with a distribution of activation energies and single frequency factor) was applied to determine the temperature experienced by the particles based on their TL curves. The temperatures indicated by the TL particles were comparable to the temperatures measured using thermocouples, with some exceptions. These exceptions include situations in which the material was not suitable for a specific temperature range (e.g., CSO heated below 200 °C for 2 h duration) or in which particle aggregation prevented the aliquots from being uniformly heated (e.g. LBO heated in the temperature chamber).