Thermoluminescence of YAG:Nd crystals coloured with x-rays

Low temperature luminescence from the near surface region of Nd:YAG

“…As expected for a distorted surface region, in which there are likely to be variations in detailed site symmetry, the TL glow peaks are wider in electron irradiated samples. The main glow peak occurs near 140 K together with two smaller ones around 40 and 90 K. The glow curves resemble those reported in earlier publications, although they differ in detail [8,21]. In the UV region the intrinsic emission, seen during RL or CL, is almost completely suppressed.…”

“…This again has characteristic rare earth line features, but the lines match to transitions from trace impurities of Tb (as listed in table 1). A similar situation has been encountered by Niklas [8]. Such differences emphasize how the CL, RL and TL methods offer complementary information arising from alternative methods of luminescence generation.…”

“…This implies there is at least a third impurity participating in the TL above room temperature. Two possible candidates are Mn and Cr and similar spectra have been cited both for Cr dopants [8,22], or in more detail, for Mn doped crystals [12,23] where the emissions at 680 and 710 nm were attributed to Mn 4+ and those at 595 nm to Mn 2+ . There are minor differences in glow peak temperatures as a function of wavelength, which may indicate that both impurities are present.…”

“…There are several possible non-equivalent lattice sites and a consequence of this is that the structures of the trapping centres in YAG are still not well identified either for luminescence or thermoluminescence (TL). Although the concept of radiationless energy transfer between traps and emission sites is widely accepted [6][7][8][9], the detailed structure of the lattice defects is still controversial. The various models that have been proposed indicate the diversity of opinion.…”