Role of defects in electron band structure and gas sensor response of La2CuO4

Abstract

Purpose This paper aims to estimate the relationship between defect structure with gas concentration for use as a gas sensor. The change in defect concentration caused a shift in the Fermi level, which in turn changed the surface potential, which is manifested as the potentiometric response of the sensing element. Design/methodology/approach A new theoretical concept based on defect chemistry and band structure was used to explain the experimental gas response of a sensor. The theoretically simulated response was compared with experimental results. Findings Understanding the origin of potentiometric response, through the generation of defects and a corresponding shift in Fermi level of sensing surface, by the adsorption of gas. Through this understanding, the design of a sensor with improved selectivity and stability to a gas can be achieved by the study of defect structure and subsequent band analysis. Research limitations/implications This paper provides information about various types of surface defects and numerical simulation of material with defect structure. The Fermi energy of the simulated value is correlated with the potentiometric sensor response. Practical implications Gas sensors are an integral part of vehicular and industrial pollution control. The theory developed shows the origin of response which can help in identifying the best sensing material and its optimum temperature of operation. Social implications Low-cost, reliable and highly sensitive gas sensors are highly demanded which is fulfilled by potentiometric sensors. Originality/value The operating principle of potentiometric sensors is analyzed through electron band structure analysis. With the change in measured gas concentration, the oxygen partial pressure changes. This results in a change in defect concentration in the sensing surface. Band structure analysis shows that change in defect concentration is associated with a shift in Fermi level. This is the origin of the potentiometric response.