Strontium cobaltite coated optical sensors for high temperature carbon dioxide detection

Carbon dioxide sorption on perovskite type metal oxide, Ba0.5Sr0.5Co0.8Fe0.2O3−δ, was studied at high temperatures for the development of a high temperature optical carbon dioxide sensor. When exposed to carbon dioxide in 600–700 °C Ba0.5Sr0.5Co0.8Fe0.2O3−δ reacts with carbon dioxide to form Sr0.6Ba0.4CO3. The sorption capacity increases with carbon dioxide pressures. The perovskite structure of the metal oxide after carbon dioxide sorption can be recovered by exposing the material to air at a temperature higher than 680 °C. The sorption rate with temperature and the high temperature sorption mechanism can be described by the homogeneous model. The optical sensor uses Ba0.5Sr0.5Co0.8Fe0.2O3−δ as the sensing material and long period fiber gratings as the optical component. The Ba0.5Sr0.5Co0.8Fe0.2O3−δ coated long period fiber grating (LPFG) can measure carbon dioxide in the concentration range of 1–30% in air (1 atm total pressure) at 600 and 700 °C. The sensor maintains its functionality after several repeated cycles of carbon dioxide detection at 700 °C.