Studying the effects of thermally diffusing Ce into the surface of YAlO3 for associated particle imaging

Abstract Active radiation environments and high-rate backgrounds pose a significant challenge towards improving the detection and characterization of Special Nuclear Material (SNM) using Associated Particle Imaging (API). Ongoing research seeks to reduce the sensitivity of a charged particle, or associated particle, detector to x-ray backgrounds through the creation and characterization of an alpha-sensitive, Ce-doped surface region of Yttrium Aluminium Perovskite (YAP). A wet-chemical layer of trivalent cerium (III) acetylacetonate hydrate was thermally diffused with a reducing atmosphere into single YAP crystals for a temperature range of 800 °C to 1500 °C. The diffusion concentration profile of the cerium compound was assayed with Rutherford Backscattering Spectrometry (RBS), where the Ce diffusion activation energy and the pre-exponential factor within YAP were found to be 1.02 ± 0.10 eV and 9.7 ± 2.0 × 10 - 15 m 2 s - 1 , respectively. Resulting transient polycrystalline structural features at the surface of the YAP crystals were investigated with X-Ray Diffraction (XRD). YAP, Yttrium Aluminium Garnet (YAG), and Yttrium Aluminium Monoclinic (YAM) phases were identified, as well as contributions from Y2O3, CeO2, Ce2O3, and the metastable hexagonal polymorph of YAlO3 (YAH). The luminescent responses of the complex surface layers to x-ray and α excitement were examined as functions of annealing temperature. Radioluminescence emissions typical of the Ce3+ 4f → 5d transition occupying both the Y3+ and Al3+ sites in YAP and YAG were observed. The brightness of the samples under alpha radiation increased as a function of diffused Ce concentration until the point of optical darkening.