SYNTHESIS, STRUCTURE AND LUMINESCENT PROPERTIES OF SAMARIUM-DOPED BOROPHOSPHATES.

Rare-earth doped solids have a number of useful scintillating and storage phosphor properties, and have received considerable attention because of their applications in sensors, optical and X-ray detectors, waveguides, lasers etc.. All samarium doped alkaline earth borophosphates were prepared by solid state reaction and melt quenched in air to form rare-earth doped glasses, glass ceramic and polycrystalline samples. Differential Scanning Calorimetry and Temperature Modulated Differential Scanning Calorimetry were carried out to extract the glass transformation properties for the glass and glass ceramic like samples. X-ray diffraction analysis was employed to investigate the phase composition and determine whether the synthesized samples were formed of glass or crystalline phases, or mixtures of both. Samples were irradiated by ultraviolet and blue light emitting sources to induce photoluminescence before and after exposure to synchrotron X-ray irradiation at the Canadian Light Source. X-ray induced luminescence spectra were also recorded. The experimental results are discussed in terms of the behavior of rare-earths in glasses and polycrystalline solids. The results indicate that while nearly all Sm3+ -doped polycrystalline borophosphates show the conversion of Sm3+ to Sm2+ upon exposure to X-rays, only certain glasses exhibit this conversion. Indeed, for a given composition, such as BaBPO5, the glass material shows no well defined Sm3+ to Sm2+ conversion, while the polycrystalline form exhibits a clear Sm3+ to Sm2+ conversion. Interestingly, all samples exhibit X-ray luminescence from Sm2+ ions during the X-ray irradiation; but there is no clear evidence of Sm2+ photoluminescence in non annealed samples after the cessation of X-ray synchrotron irradiation. [ABSTRACT FROM AUTHOR]