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Gas sensors has been currently in great demand because of serious concern over environmental pollution and public health considerations resulting from tremendous growth of industrialisation. Concurrently, there have been continuous efforts to obtain sensors with improved performance. The performance of any solid-state electrochemical gas sensor has been always rated on its response time, thermodynamic stability, operating temperature, gas sensing ability, sensitivity and gas concentration range, which is to be sensed. This article reviews the factors contributing towards a gradual development of electrochemical solidstate gas sensors in terms of a continuous tailoring of its two basic components, i.e. solid electrolyte and reference electrode.

Samarium-doped Ceria powders for solid electrolyte ceramics were synthesized by a combustion process. Cerium nitrate and samarium nitrate were used as the starting materials, and glycine was used as fuel. Decomposition of unburned nitrogen and carbon residues was investigated by simultaneous thermogravimetry analysis and differential thermal analysis experiments. The X-ray diffraction results showed that the single-phase fluorite structure forms at a relatively low calcination temperature of 800°C. X-rays patterns of the SDC powders revealed that the crystallite size of the powders increases with increasing calcination temperature. The sintering behavior results showed that more than 96% of the relative density is obtained for powders sintered at 1,100°C for 8 h. The alternating current impedance spectroscopy results showed that the SDC15 sample sintered at 1,100°C has ionic conductivity of 0.015 Scm −1 at 650°C in air. The present work results have indicated that glycinenitrate route is a relatively low-temperature preparation technique to synthesize SDC powders with a high sinterability and a good ionic conductivity.

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