Characterization of the red thermoluminescence emission of doped alumina: A case study for Al2O3: C and Al2O3: Cr,Ni

Abstract

We herein report on the radiation effect on the red thermoluminescence (TL) emission of synthetic Al2O3:C (commercial TLD-500 supplied by Harshaw) and Al2O3:Cr,Ni (grown by the Verneuil method). The materials were previously characterized by cathodoluminescence (CL), displaying significant differences in the UV-IR spectral emission range related to the presence of dopants. Whilst the CL curve of C-doped alumina exhibits four wavebands peaked at 325 (due to F+ centers) 411 (F centers), 648 (Fe3+) and 785 nm (Ti3+), the Al2O3:Cr,Ni sample shows a narrow, sharp, high intensity maximum at 692 nm with two vibronic side bands of lower intensity at 679 nm and 713 nm attributed to the R-lines of Cr3+. The red TL emission at 650 nm of both materials indicates that they could potentially be used as dosimeters since (i) are sensitive to ionizing radiation at doses over 10 mGy; (ii) show a linear dose response in the range of 10–100 mGy with regression coefficients of 0.999 and (iii) can be reusable with negligible variation in the intensity (never higher than±0.8%) and no observed changes in the shape of the TL curves. The red glow emission intensity corresponding to the C-doped sample hardly changes with the storage time, however Al2O3:Cr,Ni fades significantly (ca 70%), up to ~700 h of storage following a behavior that can be fitted to a decreasing exponential function. Tmax-Tstop test suggests the coexistence of continuous and discrete trap systems in both compounds.