Insights into the Relationship between Crystallite Size, Sintering Pressure, Temperature Sensitivity, and Persistent Luminescence Color of Gd2.97Pr0.03Ga3Al2O12 Powders and Ceramics

Abstract

In order to obtain Gd2.97Pr0.03Ga3Al2O12 powders with different crystallite sizes, a modified Pechini (sol–gel) method was used. Powders were then used for the preparation of ceramics by a high-pressure low-temperature sintering method. The impact of crystallite size and pressure applied during the sintering procedure on conventional and persistent luminescence was investigated and analyzed. It was found that the emission color is strictly dependent on the crystallite size, as such phenomenon may be used in the field of advanced anti-counterfeiting. The spectroscopic properties of Gd2.97Pr0.03Ga3Al2O12 were characterized by means of photoluminescence measurements. The kinetics of luminescence were measured in order to analyze the energy transfer between 3P0 and 1D2 excited states that also take an active role in the persistent luminescence process. It was found that an increase in the crystallite size led to a higher energy transfer from the 3P0 to 1D2 level and a change in the emission color. As such, it was studied for potential application in ratiometric optical thermometry. The effect was also investigated in terms of persistent luminescence. It was also found that the sintering pressure causes changes in the crystallographic parameters of the powders and, in consequence, has a great impact on the optical properties of ceramics. The conducted research gives insights into the mechanism of persistent luminescence and expands the application field of optical storage materials.