Abstract
Impedance-type humidity sensors based on EuCl2, Eu2O3 and EuCl2/Eu2O3 blend films were fabricated. The electrical properties of the pure EuCl2 and Eu2O3 films and EuCl2/Eu2O3 blend film that was blended with different amounts of EuCl2 were investigated as functions of relative humidity. The influences of the EuCl2 to the humidity-sensing properties (sensitivity and linearity) of the EuCl2/Eu2O3 blend film were thus elucidated. The impedance-type humidity sensor that was made of a 7 wt% EuCl2/Eu2O3 blend film exhibited the highest sensitivity, best linearity, a small hysteresis, a fast response time, a small temperature coefficient and long-term stability. The complex impedance plots were used to elucidate the role of ions in the humidity-sensing behavior of the EuCl2/Eu2O3 blend film.
Highlights
Developing humidity sensors have attracted much interest because humidity is an important role in maintaining human health and an excellent quality of products [1,2,3].humidity sensors must have high sensitivity, a wide working humidity range, good linearity, fast response/recovery times, low hysteresis, good reversibility, stability and ease of fabrication for the mass production of humidity devices for using in food storage, industrial production and environmental monitoring [4,5]
Ceramic materials, including metal oxides, perovskite- and spinel-type oxides and their hybrid systems, have some superiority in function because of their good chemical stability, high heat resistance, good water resistance under high humidity, cost-effectiveness and fast response to the changes of humidity [7,15], which means they can be applied to humidity detection
A very similar X-ray diffraction (XRD) spectrum has been reported for Eu2 O3 prepared by using a solution method [31]
Summary
Developing humidity sensors have attracted much interest because humidity is an important role in maintaining human health and an excellent quality of products [1,2,3].humidity sensors must have high sensitivity, a wide working humidity range, good linearity, fast response/recovery times, low hysteresis, good reversibility, stability and ease of fabrication for the mass production of humidity devices for using in food storage, industrial production and environmental monitoring [4,5]. Many materials, including ceramic, polyelectrolyte, organic polymer and composite materials, have been applied to humidity sensors [1,6,7,8,9,10,11,12,13,14]. Ceramic materials, including metal oxides, perovskite- and spinel-type oxides and their hybrid systems, have some superiority in function because of their good chemical stability, high heat resistance, good water resistance under high humidity, cost-effectiveness and fast response to the changes of humidity [7,15], which means they can be applied to humidity detection. The humidity-sensing properties of ceramic humidity sensors is strongly influenced by the surface activity and the porous structure of the ceramic materials [15]. Many reports focused on researching the microstructure and morphology of ceramic materials and doping various dopants to tune the physico-chemical properties of ceramic materials [6,16]
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