A Model of Lattice Defects in Sapphire

Thermal- and photo-induced transformations of luminescence centers in αd-Al2O3 anion-defective crystals

“…4, in the same temperature range (350-500°C) there also occurs an increase in the concentrations of individual F + and F centers involved in the formation of defect clusters similar to those observed upon annealing of the neutron irradiated crystals in [18]. Some details of the changes in the concentration of F + centers depending on the annealing temperature, which were established in [17] from the optical absorption spectra, are also in good agreement with the results presented Fig. 4 (curve 1) and obtained from the analysis of the TL spectra measured in the main peak.…”

“…A comparison of the results presented in the table with the data available in the literature has demon strated that there is a similarity between the main types of defects found in the α Al 2 O 3 samples with the ini tially perfect structure after the irradiation with neu trons [17,18] and in the anion defective α Al 2 O 3 sam ples irradiated with UV light at 625°C, which were studied in our work. Optical absorption and photoluminescence of F type defects in the anion defective corundum samples irradiated with UV light at a temperature of 625°C …”

“…The absorption band at 300 nm is assigned to the F 2 centers, i.e., the oxygen divacancies with four electrons, whereas the band at 355 nm is attributed to the centers, i.e., the oxygen divacan cies with three electrons. Examples available in the lit erature on the identification of the F 2 and centers from the spectra of their optical absorption and lumi nescence excitation are presented for α Al 2 O 3 samples in which anion defects have been produced by irradia tion with corpuscular emissions, neutrons, protons, electrons, and accelerated ions of different chemical elements [15][16][17][18]. In contrast to radiation induced defects, the defects in the oxygen sublattice of the α Al 2 O 3 samples studied in our work were produced dur ing the growth of crystals under reducing conditions.…”

“…There fore, the obtained data on the optical absorption and luminescence excitation spectra give grounds to assert that the anion defective corundum crystals irradiated with UV light at 625°C contain F 2 type centers. The absorption band at 360 nm, which is assigned to centers, according to the data available in the litera ture [17] is attributed to the luminescence in the band at 380 nm. The resolving power of the spectrometers at our disposal was not sufficient for recording the pho toluminescence excitation spectra of centers, so that their presence in the samples could be judged only from the characteristic absorption band observed at 360 nm.…”

Dosimetria usando luminecência opticamente estimulada: aplicações, propriedades físicas e caracterização de materiais dosimétricos

“…O Al 2 O 3 :C tem sensibilidade a exposições que vai desde 10 Gy até 100 Gy [10,11]. Suas respostas em dosimetria individual externa, datação e dosimetria espacial para Raios-X, , , e partículas pesadas, já são bastante conhecidas [12]. Alguns exemplos são mostrados no gráfico da Figura 1.9.…”