CsBr is a rare element with a melting point of about 636 deg C. It is an ionic compound of caesium and bromine. This white powder is widely used as an analytical reagent and X-ray phosphor screen. However, it has a few drawbacks. For instance, it has an unusually high crystallization temperature and is very water-soluble. In addition, it is easy to burn if it is exposed to too much heat. So, it is best avoided in direct contact with molten metals or liquids.
The best way to extract the most useful information from a CsBr evaporation source is to observe the temperature distribution. Here, the central portion and the peripheral portion are both about 1 deg C cooler than the rest. To find out what the difference is, we can use a graph.
Similarly, to find out what the best pretreatment temperature is, we can make a chart. The highest pretreatment temperature is preferably within the range of formula (1). If the phosphor is a columnar material, the diameter of the largest phosphor columnar body is also related to the average temperature of the evaporation source. A typical example is using a dry nitrogen gas atmosphere.
Finally, to find out what the best CsBr evaporation source could be, we will consider the alkali halide phosphor layer. A typical phosphor layer consists of several layers, namely the coating layer, the matrix and the point-like portion. Each of the layers is made of different crystallinity and thus, the thickness of the phosphor layer varies from one layer to the next.