Polycrystalline substance of formula Bi12 Si O20, process for manufacturing the substance, and radiation detection device using this substance

This invention concerns a polycrystalline substance of chemical formulation Bi12 Si O20, the process for fabricating it and the radiation detection devices, particularly of X rays, utilizing this substance. The industrial synthesis of Bi12 Si O20 monocrystals is known. The monocrystal has a high X ray absorption factor. It can therefore be used in X ray radiography but the monocrystals presently available do not lend themselves well to the visualization of large areas. For such applications large size thin plates or discs would be required but the present techniques for synthetizing a monocrystal do not enable these requirements to be met. This invention makes it possible to obtain plates or discs suitable for the X ray visualization of large areas or zones. It consists in producing a polycrystalline substance comprising cubic structure monocrystals of between 2 and 6 micron in size and with the Bi12 Sisub(1-x) O20 formulation, where x is between 0 and 0.1, by employing the techniques of ceramic and polycrystalline ferrite fabrication