Computer-assisted method for determining the onset quenching temperature of luminescent thermographic phosphors

The onset quenching temperature of thermographic phosphors is determined with the use of the CALQUEN.BAS computer program, which is based on a simple line-of-best-fit technique. Using the method of best-fit or linear regression, two equations linearly approximate the lifetime calibration curve (data) of a thermographic phosphor and determine the initial point of temperature dependence, which is the intersection of the two lines. The features of the program are described, the theory underlying the method is presented, and the measured decay lifetimes of several high-temperature thermographic phosphors are used to perform onset quenching temperature calculations. It is found that LuPO₄:Dy³⁺ has the highest onset quenching temperature, 905.02°C, of all the orthophosphates tested. LuPO₄:Eu³⁺, YPO₄:Eu³⁺, Y₂O₃:Eu³⁺, and LaPO₄:Eu³⁺ exhibited onset quenching temperatures of 756.5, 668.5, 506.9, and 461.7°C, respectively