The effect of water on the thermoluminescence properties in various forms of calcium sulfate samples

Abstract

The present study investigates whether thermoluminescence (TL) features are prevalent over calcium sulfate samples, regarding their lever of hydration. Three groups of calcium sulfates -dihydrate (gypsum), hemihydrate (bassanite) and anhydrous (anhydrite)- are investigated, of both commercial and mineral origin. The study includes TL features such as TL glow curve shapes, the stability of TL peaks after successive cycles of measurements, and the estimation of the kinetic parameters of stable TL peaks. Moreover, the slurry of calcium sulfate with water is being studied, to investigate its prevalence as an effective zeroing mechanism. The results indicate the presence of stable TL peaks around 280 °C for all of the groups of calcium sulfates, while the TL sensitivity of the samples depends on their water content and stabilizes after three heating cycles up to 500 °C. Anhydrite shows stability even from the initial measurement, while the hemihydrates and dihydrates could be used for dating applications using TL by means of a multiple aliquot protocol.