Design and engineering of ionization gas sensor based on Mn nano-flower sculptured thin film as cathode and a stainless steel ball as anode

In this work a field ionization gas sensor based on 3-fold symmetry Mn nano-flower sculptured thin film as cathode and a stainless steel ball (SSB) as anode is used. The breakdown voltage of the system was studied for nitrogen, oxygen, argon, air and carbon mono-oxide gases. Investigations for these gases at different distances between anode and cathode (40,100 and 200 mu m), anode (SSB) diameter sizes of 2, 6 and 10 mm and different gas pressures (0.2-1000 mbar) confirmed Paschen's Law. Results for different anode sizes showed that by decreasing the ball size at high pressures the breakdown voltage decreased, while at low pressures the opposite behavior was observed. For pd values (mbarcm) between 0.025 and 0.2 mbar cm and for different gases studied in this work a good gas selectivity was obtained. Lower breakdown voltages at medium gas pressures are obtained when comparison is made with the published data for different materials (i.e., CNT, Cu, Au, Ag and ZnO) and designs. The effective secondary emission coefficient of Mn nano-flowers and the ratio of the probability of secondary electron emission of Mn to that of other types of cathodes made of different materials showed higher values. These results suggest that Mn can act as a good material in ionization sensors and the nano-sculptured structure designed and engineered in this work can enhance the sensor's performance. Nano-structure and morphology of the produced samples were obtained by field emission electron microscope (FESEM) and atomic force microscope (AFM) analyses. (C) 2018 Elsevier B.V. All rights reserved.