P-036

Greta Inkrataitė

greta.inkrataite@chgf.vu.lt

Jan-Niklas Keil, Thomas Jüstel, Ramūnas Skaudžius

Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius university, Lithuania

Photoluminescence Effects of Praseodymium and Boron Doped Compounds with a Garnet Structure

In order to convert high-energy radiation, such as gamma or X-rays, into visible light scintillating materials are needed. Over the years many different candidates to fit the requirements were examined. However, compounds with garnet structures have attracted a particularly large amount of attention. Praseodymium doped lutetium and gadolinium aluminum garnets have high density, high thermal stability, rather efficient luminescence processes, and thus high quantum efficiency which are needed for a good scintillator. However, further optimization and improvement are still required especially w.r.t. a reduced decay time. The duration of the luminescence decay is important because if it is very short then the more signals can be measured within a defined timeframe, resulting in a better resolved and higher quality image, for example in CT or PET devices. One way to improve materials properties is to doping the aforementioned compounds with different elements. As such, by doping we could potentially be able to improve key aforementioned parameters: emission intensity, quantum efficiency and decay times. One of these  elements is boron. Primarily, it can be used as a flux, and also B3+ ion has a suitable neutron capture cross section and can also help absorb gamma radiation. However, garnets can be doped with larger amounts of other elements. In this case, we replaced some of the aluminium with scandium. Lutetium aluminium garnets and gadolinium aluminium garnets doped with Pr3+ and B3+ were obtained as a result. 

In the present work, the effect of boron on the various characteristic of the LuAG and GdAG doped by praseodymium is investigated. Garnets doped with different amounts of boron were synthesized by the aqueous sol-gel method. The phase purity of the samples was analyzed by means of X-ray diffraction (XRD). The morphology of the compounds was evaluated by using scanning electron microscopy (SEM). Photoluminescence properties such as emission and excitation spectra, decay curves, quantum efficiency and temperature dependency of the emission and excitation spectra have been investigated. Radioluminescence was also measured in order to determine the scintillation properties of the samples. The positive impact of boron addition into the garnet structure on the luminescence properties will be discussed in detail.