An alternative method of preparation of dosimetric grade α-Al2O3: C by vacuum-assisted post-growth thermal impurification technique

Single-crystal alpha-Al2O3 (10 x 10 mm(2), 0.4 mm thick) was treated in vacuum at temperatures below its melting point in the presence of graphite. The possibility of this approach as an alternative method to the crystal growth in the reduced atmosphere for obtaining dosimetry grade alpha-Al2O3:C for TL and OSL dosimetry applications has been explored. The absorption peaks at 203, 225, and 255 nm in the treated sample confirmed the formation of negative ion vacancy in the crystalline alpha-Al2O3. The TL readout of the processed samples showed two well-defined glow peaks at 56degreesC and 19 VC for a 4 K/s heating rate. The TL and OSL sensitivities of the samples were seen to strongly depend on process temperature and process time and are comparable to those produced by conventional method. The OSL response of these samples is found to be linear from 50 muGy to 1 Gy. The results show that, with this approach, it is possible to introduce the desired dosimetric traps into crystalline alpha-Al2O3 in a controlled manner. (C) 2004 Elsevier Ltd. All rights reserved.