Limiting current oxygen sensor based on La0.8Sr0.2Ga0.8Mg0.2O3−δ as both dense diffusion barrier and solid electrolyte

Abstract La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3− δ (LSGM) was synthesized by a high temperature solid-state reaction. The crystal structure, relative density and electrical conductivity were measured with XRD, Archimedes method, and Van Der Pauw DC four-probe method. A limiting current oxygen sensor based on LSGM as both solid electrolyte and dense diffusion barrier was prepared by a Pt paste bonding method. The results show that LSGM has pure perovskite structure (cubic symmetry with space group of Pm-3m (No.221)), high density (relative density is 97.6%) and electrical conductivity (0.18 S∙cm −1 at 1073 K). The sensor works optimally over temperature range of 973‒1123 K and oxygen concentration of 1.92%‒21%. The operating voltage ranges from 0.67 to 0.98 V. The limiting current is in proportion to oxygen concentration. The sensor has the highest sensitivity at 1123 K and low measurement error of less than 4%.