A Route towards More Sensitive ZnFe2O4 Gas Sensors
Electroceramics 13 Conference 2012
Andris Šutka, Gundars Mežinskis, Andrejs Lūsis

For enhancement of the sensitivity electron concentration in the n-type gas sensor material needs to be regulated in order to achieve equilibrium between optimal concentration of surface oxygen species and width of the depletion layer. The aim of the present work is to demonstrate that the sensing characteristics of a metal oxide semiconductor gas sensor using n-type zinc ferrite can be improved by controlling iron stoichiometry in composition. The sol-gel auto-combustion has been used to produce nano-sized ZnFe2+zO4±δ materials. The sensors were characterized by using XRD, SEM and DC gas sensing measurements. To identify contribution of the depletion layer and grain interior, ac impedance spectroscopy (IS) measurements were performed. XRD analysis reveals a pure cubic spinel type structure for zinc ferrite samples tested as gas sensors. SEM micrographs of the samples reveal microstructures with nanosized grains and open pores. No morphological differences were apparent between samples with various iron content. The complex impedance spectra shows a presence of two gas sensitive material phases with different electric properties attributed to grain interior and depletion layer. Depletion layer of the grain of the sensing material gives higher signal due to higher influence of test gas to the electron concentration at the boundary layer. Overall, sensitivity by going from iron deficient to excess can be improved for the four times due to increase adsorbed oxygen states on grain surface. By reaching z > 0,1 sensitivity again drops due to remarkable decrease of depletion layer width, as concluded from IS analysis.

Atslēgas vārdi
Zinc ferrite, gas sensor

Šutka, A., Mežinskis, G., Lūsis, A. A Route towards More Sensitive ZnFe2O4 Gas Sensors. No: Electroceramics 13 Conference, Nīderlande, Enschede, 24.-27. jūnijs, 2012. Enschede: University of Twente, 2012, 51.-51.lpp.

Publikācijas valoda
English (en)
RTU Zinātniskā bibliotēka.
E-pasts: uzzinas@rtu.lv; Tālr: +371 28399196