Nanocrystalline complex oxides NixCo3-xO4: Cations distribution impact on electrical and gas sensor behaviour

Publication date: Available online 20 February 2020Source: Journal of Alloys and CompoundsAuthor(s): S.A. Vladimirova, K. Ya Prikhodko, M.N. Rumyantseva, E.A. Konstantinova, A.S. Chizhov, N.O. Khmelevsky, A.M. GaskovAbstractNanocrystalline complex oxides NixCo3-xO4 (0 ≤ x ≤ 1) were obtained via co-precipitation of oxalates with subsequent thermal decomposition and characterized in detail by ICP-MS, XRD, TEM, XPS and EPR methods. It was found that complex oxides NixCo3-xO4, where x ≤ 0.25, can be considered as Co3O4 based solid solutions with a normal spinel structure, while NixCo3-xO4 with a high nickel content (x = 0.70, x = 1) have a partially or completely inverse spinel structure. All complex oxides NixCo3-xO4 (0 ≤ x ≤ 1) are characterized by p-type conductivity, which sharply increases with the increase in Ni content. Sensor measurements in the presence of 5–20 ppm CO demonstrated that in the temperature range 80–150 °C the sensor response of NixCo3-xO4 decreases with an increase in Ni content that can be explained by the decrease in the concentration of oxygen chemisorbed on the NixCo3-xO4 surface. However, the lower limit of CO detection (measured at 120 °C) decreases from 1.08 ppm for Co3O4 down to 0.39 ppm for Ni0·1Co2·9O4 that makes NixCo3-xO4 complex oxides promising materials for low temperature detection of carbon monoxide at ultra low concentrations.
Source: Journal of Alloys and Compounds - Category: Chemistry Source Type: research