Investigations of Optical and Scintillation Properties of $({rm Lu}_{0.1}{rm Y}_{0.9}){rm AlO}_{3}!:!{rm Nd}0.1$%

摘要

$({rm Lu}_{0.1}{rm Y}_{0.9}){rm AlO}_{3}!!:!!{rm Nd}0.1%$ crystal was grown by the ${rm mu}$ -PD method and pure YAP single crystal was prepared as a reference sample. Then, two annealing procedures were performed for each sample at $1350^{circ}{rm C}$ and $1500^{circ}{rm C}$ for 20 hours in oxygen atmosphere to improve the crystallinity and scintillation properties. The XRD results for all the samples were consistent with JCPDS data (#33-0041) and possessed a space group of orthorhombic Pbnm while no impurity peaks were observed. The FWHM values of X-ray rocking curve measurements of the as-grown crystals and the crystals annealed at $1500^{circ}{rm C}$ were 70 and 200 arcsec, respectively. It can be due to the onset of decomposition. In the transmittance measurements, intense absorption peaks were observed approximately at 240 and 290 nm and they were consistent with the bands for color centers: the two-electron F center and one-electron ${rm F}^{+}$ center, respectively. These absorptions were enhanced by Lu substitution. The radio-luminescence spectra show several emission peaks due to ${rm Nd}^{3+}$ 4f-4f transitions and the most intense of which were assigned to $^{2} {rm F}(2)_{5/2}-^{4} {rm F}_{5/2}$, $^{2} {rm F}{(2)}_{5/2}-^{4}{rm G}_{7/2}$ and $^{2} {rm F}{(2)}_{5/2} -^{4}{rm G}_{9/2}$ transitions at 395, 540 and 550 nm, respectively. The light yield after annealing annealing was as high as $5025 pm 500~({rm N}_{rm phe}/{rm MeV})$ when using Si-APD (S8664). The scintillation decay time constants were evaluated to be 3.44–3.80 $mu{rm s}$ for each sample. Afterglow upon X-ray excitation of the as-grown and annealed samples coupled with PIN Si-photodiode was found to be approximately 1200 and 1000 ppm after 100 ms.