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The role of carbon in the formation mechanism of F-type centers in α-Al2O3:C,Mg single crystals
摘要： In this study, an α-Al2O3:C,Mg single crystal was grown using the Czochralski method with graphite resistance heating, Al2O3, MgO, and graphite powder as raw materials. Both the graphite heating unit and the shield served as the carbon source during the growth process. The structure and the optical properties of the crystal were investigated. The as-grown crystal shows a prominent absorption band at 206 nm, 230 nm, and 256 nm. The excitation-emission (EE) spectrum reveals a weak luminescence center (435/510 nm) that is attributed to the F2t (2 Mg). We calculate the concentration of the F-type centers using Smakula’s equation. Using the first principles simulation method, we studied the relation between the C atoms and the absorption properties of the crystal, and we discuss the role of carbon in the formation mechanism of the F-type luminescence centers for a α-Al2O3:C,Mg crystal.
关键词： Color centers,Al2O3:C,Crystals growth,Mg
更新于2025-09-23 15:22:29
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Recovery of α-Al2O3 from Ionizing Radiation Dosimetric Sensors
摘要： Corundum, sapphire or α-Al2O3 is an important technological material in many optical and electronic applications such as solid-state lasers, optical windows and, more recently, as a radiation detector. Landauer (Glenwood, IL, USA) accumulated large number of archived and stored Luxel? dosemeters composed of Al2O3:C, which were subjected to a recovery process. Due to the importance of this advanced crystalline material in OSL dosimetry, a recovery process was developed based on the dosemeters calcination and Al2O3:C has been reused in manufacturing of new dosemeters. This paper does not aim to optimize the recovery process, but provides an opportunity to study the involved process parameters and to recover this valuable crystalline material from used dosemeters. To the best of our knowledge no other recovery process involving this dosimetric material was described in scientific literature. Fourier Transform Infrared Spectrometry (FTIR), Thermogravimetry/Differential Thermoanalysis (TG/DTA), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Optically Stimulated Luminescence (OSL) and Rietveld Refinement were used to characterize the recovered material and to check for the stability of its structural and dosimetric properties.
关键词： recovery process,optically stimulated luminescence,Al2O3:C
更新于2025-09-10 09:29:36
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THERMOLUMINESCENCE OF NEWLY DEVELOPED HIGHLY SENSITIVE α-Al2O3:C BY THE VERTICAL GRADIENT FREEZING METHOD
摘要： A highly sensitive α-Al2O3:C crystal was directly grown by the vertical gradient freezing (VGF) method using Al2O3 and graphite powder as the raw materials. The main thermoluminescence (TL) characteristics of α-Al2O3:C detectors grown by the VGF method and TLD-500K detectors were compared. The α-Al2O3:C grown by the VGF method shows good dosimetric properties, such as high TL sensitivity (152 times higher than that of the TLD-100 at heating rate of 1°C/s), an extremely low residual signal of 0.03%, a minimum measurable dose of 0.12 μGy and an excellent linear response within the dose range studied from 1 μGy to 10 Gy. The α-Al2O3:C detectors grown by the VGF method have a higher sensitivity and a better linear response compared to the TLD-500K detectors. Both kinds of α-Al2O3:C can be used in an unannealed form and to measure the very low dose in environmental monitoring and personnel dosimetry.
关键词： α-Al2O3:C,personnel dosimetry,dosimetric properties,vertical gradient freezing method,thermoluminescence,environmental monitoring
更新于2025-09-09 09:28:46