Preparation and properties of CaW0₄ core and AgBr shell microcrystal emulsion

Abstract

The non-silver core (CaW0₄) with an average grain size of 1 urn was shelled by silver halidc (AgBr). The thickness of the AgBr shell was about 10 15 per cent of the CaW0₄ core/AgBr shell grain size. The silver content was only 1 per cent of the non-silver core and silver halide shell emulsion weight in g. After exposure of X-ray radiation, the CaW0₄ core after absorbing X-rays emitted fluorescence (350 560 nm) to expose the AgBr shelled on the surface of CaW0₄ microcrystals. The light-sensitive AgBr might absorb the radiation from external and internal directions. Therefore the sensitivity of this kind of non-silver core and silver halide shell emulsion under X-ray exposure is much higher than that of the AgBr emulsion with the same silver content, and the amount of silver will be much less than the conventional photographic emulsion. Finally, the CaW0₄ core is dissolved in EDTA solution at a certain temperature and range of pH, causing the transparency of the CaW0₄core/AgBr shell film to be greatly increased.

Key Words:

• CaW0₄ core
• AgBr shell
• Emulsion
• Microcrystals