Large polycrystalline slat plate esp of phosphor - made by solidification of salt melt on low melting pt metal bath

摘要

A plate-like salt body is produced by allowing a salt melt (SS) to solidify above a metal bath (MB) of lower melting point. Pref. the salt melt (SS) consists of an alkali or alkaline earth metal halide and the metal bath (MB) contains one or more of Sn, Pb, Bi, and Tl. Appts. for carrying out the above process has (a) a rectangular melting tank for holding a metal bath (MB); (b) a heating system (HS) allowing appln. of a temp. gradient along the melting tank (SW); (c) a refilling device (MF); and (d) a slide (SCH) which can be moved over the bath surface to divide the bath surface into hotter and colder regions. Also claimed is a large surface, polycrystalline, plate-like salt body with a grain size of more than 1cm. USE/ADVANTAGE - For prodn. of large plates of esp. of doped alkali or alkaline earth metal halide phosphor for detecting energetic radiation in high energy physics, x-ray diagnostics and nuclear medicine. A high quality, fully transparent, polycrystalline plate of any size can be produced eg., the plate may be of patient size to allow complete patient imaging in a single exposure. The plate is made by a simple process, has high surface quality and is plane-parallel so that no finishing, other than cutting to size is required.