Synthesis of embedded and isolated Mg0.5Zn0.5Fe2O4 nano-tubes and investigation on their anomalous gas sensing characteristics

We have investigated the gas sensing characteristics of wet chemical synthesized 1D hollow Mg0.5Zn0.5Fe2O4 tubes embedded into porous alumina template and their isolated counterpart coated on quartz substrate. Both embedded and isolated Mg0.5Zn0.5Fe2O4 nano-tubes show promising response towards H2, CO, and N2O gases. During the measurement of gas sensing characteristics, it is observed that irrespective of the test gas (H2, CO, N2O) type, test gas concentration (10–1660 ppm) and operating temperature (250–380 °C) the embedded tubes exhibit n-type whereas isolated tubes reveal p-type sensing characteristics. Such inversion of dominant charge carriers (from n to p type) from embedded to isolated Mg0.5Zn0.5Fe2O4 nano-tubes is related with the higher chemi-adsorption of oxygen over isolated tubes than their embedded counterpart (when kept in air prior to the exposure of test gas). The present article thus describes the potential gas sensing application of 1D ferrite sensors and illustrates the possibilities of tailoring the electronic characteristics of ferrites by modifying their surface to volume ratios.