Abstract
This paper presents the synthesis of gadolinium aluminate (GdAlO3), an oxide compound with a perovskite structure, for applications as a capacitive and/or resistive humidity sensor. Gadolinium aluminate was synthesized by the sol-gel self-combustion method. This method allowed us to obtain a highly porous structure in which open pores prevail, a structure favorable to humidity sensors. Most of the materials studied as capacitive/resistive humidity sensors have significant sensitivities only with respect to one of these types of sensors. In the case of the studied gadolinium aluminate with p-type electric conductivity, the relative humidity of the air has a significant influence on both capacitive and resistive types of electric humidity sensors. The capacity increases about 10,000 times, and the resistance decreases about 8000 times as the relative humidity increases from 0 to 98%. The investigated gadolinium aluminate can be used successfully to obtain high-sensitivity capacitive and/or resistive humidity sensors.
Highlights
Humidity is a physical parameter that describes the amount of water vapor found in the atmosphere
This paper presents the synthesis of gadolinium aluminate (GdAlO3), an oxide compound with a perovskite structure, for applications as a capacitive and/or resistive humidity sensor
Gadolinium aluminate was synthesized by the sol-gel self-combustion method
Summary
Humidity is a physical parameter that describes the amount of water vapor found in the atmosphere. It is an extremely important factor in many industrial sectors [1,2]. For the measurement and control of humidity, it is necessary to develop high-performance humidity sensors using environmentally friendly materials and processes. The operation principle of ceramic humidity sensors is based on two methods of measuring humidity: the resistive electrical method, based on the variation in the effective electrical conductivity of a material in the presence of water vapor, and the capacitive electrical method, based on the variation in the effective dielectric constant of a porous dielectric material in the presence of water vapor. Perovskites (simple or doped, prepared through various methods) occupy a very important place in terms of applications concerning metal–air batteries [4], supercapacitors [5,6], and humidity/gas sensors [7,8,9,10,11]
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