K. M. Mathew

Preparation of tritiated polystyrene coated radioluminescent phosphor

Soft beta-particles emitted by tritiated polystyrene are impinged upon a copper activated zinc sulphide phosphor to provide self-sustained light sources for nocturnal illumination of watch dials and timepieces, product advertisements, telephone numbers, exit signs etc. For this purpose phenylacetylene was partially reduced with tritium in di-isopropyl ether medium using 10% Pd/CaCO3 poisoned with quinoline to give styrene. Styrene was polymerized to polystyrene by g-radiation (200 kGy dose). The copper activated zinc sulphide phosphor was then coated with that tritiated polystyrene to give self-sustained light sources.

Stability of tritiated polystyrene coated zinc sulphide phosphor

Copper activated zinc sulphide phosphor was coated with tritiated polystyrene to give self-sustained light sources. The stability of the zinc sulphide phosphor coated with polystyrene was studied. It is suggested that the drastic reduction in light output over a period of two years may be due to the phosphor damage rather than loss of radioactivity.

Salient features in the preparation of promethium-147 activated zinc sulphide phosphor light sources

Activation of zinc sulphide phosphor with beta radiation of 147Pm will provide self-sustaining light sources and are widely used as nocturnal illumination devices. Use of 147Pm as energy source is most promising since it forms non-volatile salts. By virtue of this property, it has been precipitated as hydroxide from its aqueous solution for in situ deposition on zinc sulphide phosphor. In this paper, the details of various reaction parameters such as the rate of deposition of 147Pm(OH)3 on ZnS, duration of shaking, specific activity of phosphor and effect of fatty acid (additive) concentration versus luminosity are illustrated with experimental evidence so as to obtain, under optimum conditions, an overall luminosity of 1000 micro lamberts (μlm).