PHOTOLUMINESCENCE STUDY OF (CAO)(1-X)(ZNO)(X) POWDER SOLIDS IN AIR

Luminescence from (CaO)(1-x)(ZnO), (x = 0-1) powder solids, prepared b y thermal treatment in air at 1423 K, was observed at room temperature by means of high-energy UV excitation (5.2-6.2 eV). In general, broad emission bands centred in the visible region of the spectrum were rec orded, with features dependent upon the excitation wavelength as well as on the sample nature. The presence of small quantities of zinc with in the CaO results in a dramatic enhancement of the photoluminescence intensity, reaching a maximum at 1% addition of Zn atoms/Ca + Zn atoms . In this case, a nearly twenty-fold increment in photoluminescence in tensity was observed. The emission band showed a peak at 435 mm (2.85 eV) and was excited to a maximum by 210 nm (5.9 eV) light. Photoinduce d electron transfer, followed by recombination processes involving oxy gen anion vacancies as well as photogenerated F+ and F centres, are po ssibly the cause of the observed luminescence.