X-RAY DIFFRACTION STUDIES OF THE STRUCTURAL ORIGIN OF SOME OPTICAL EMISSION BANDS IN ION-DOPED NaCl CRYSTALS. A. E. Cordero-Borboa, Instituto de Fisica, UNAM. A.P. 20-364, D.A. Obregon Mexico D.F. 01000, Mexico.

X-ray diffraction studies were carried out together with luminescence measurements for NaCl:Sr⁺²:Eu⁺², NaCl:Eu⁺² and NaCl:Pb⁺² single crystals under thermal annealing treatments at 200^oC. The weak diffracted beams, coming out from the precipitation of secondary phases into the NaCl matrixes, were enhanced by using a simple pneumatic grinder designed and built to obtain small single-cristal spheres of optimum size for minimize the absorption effects. This device offers an advantage over previous grinder systems in that it allows the selection in advance of the final diameters of the crystal spheres by means of pneumatic expulsion through a standard brass gauze. It was found that the precipitation of a secondary SrCl² phase and a fluorite-type EuCl² phase into the NaCl matrixes are responsible for the presence of emission bands peaking at 407 and 410 nm in the optical fluorescence spetra of specimens annealed for long periods.