Effect of Structure on Sensor Properties of Oxygen-Deficient Perovskites, A(2)BB ' O-5 (A = Ca, Sr; B = Fe; B ' = Fe, Mn) for Oxygen, Carbon Dioxide and Carbon Monoxide Sensing

摘要

The remarkable sensor properties of a series of oxygen-deficient perovskites, Ca2Fe2O5, Sr2Fe2O5, Ca2FeMnO5 and Sr2FeMnO5, and the impact of structural order on gas sensing response have been investigated. The sensor behavior of defect-ordered oxygen-deficient perovskites have not been studied before. Among the four materials investigated in this work, the ordered compound, Ca2Fe2O5, shows remarkably versatile sensing properties for all three gases, oxygen, carbon dioxide and carbon monoxide. This material is a semiconductor, and its electrical charge-transport increases systematically as a function of oxygen partial pressure, and decreases as a function of carbon dioxide and carbon monoxide concentrations. The recovery of charge-transport upon completion of gas sensing cycles for all gases is nearly perfect, and its crystal structure remains intact, as confirmed by Rietveld refinements with powder x-ray diffraction data. The variation of gas sensing properties as a function of structure and composition is interesting. Most remarkable is the versatility of Ca2Fe2O5, and its sensitivity to O-2, CO2 and CO.