Chemical sensors based on powdered phosphors

We have developed a method to prepare powdered phosphors which can serve as chemical sensors for a variety of gases. These sensors indicate the presence of the gas by changes in the photoluminescence (PL) intensity relative to N2 as a reference gas. Specifically, we have found that the PL of the CdS:Te phosphor increases by as much as 50% when exposed to ammonia and decreases by 50% when exposed to sulfur dioxide. This phosphor also responds to a lesser degree to O2 and water. We have also explored other common phosphors based on ZnS, ZnxCd1-xS, CaS, and SrS. The ZnS containing phosphors do not show any changes in PL upon exposure to either ammonia or sulfur dioxide while the CaS phosphors respond to sulfur dioxide and water.