Mixed conductivities of A-site deficient Y, Cr-doubly doped SrTiO3 as novel dense diffusion barrier and temperature-independent limiting current oxygen sensors

A-site-deficient Y, Cr doubly doped SrTiO3 ((Y0.08Sr0.92)(1-x)Ti0.8Cr0.2O3-delta (x = 0.01, 0.03, 0.05)) powders were synthesized via sol-gel method, followed by sintering at 1450 degrees C at ambient condition. The phase composition, mixed conductivities, and sensing performance are characterized to identify the influence of A-site deficiency on the Yand Cr-doubly doped SrTiO3. The ionic conductivity and total conductivity of (Y0.08Sr0.92)(1-x)Ti0.8Cr0.2O3-delta clearly increase and decrease upon an increase in the A-site deficiency, respectively. The enlarged saddle point and decreased relaxation time are responsible for the augmentation of ionic conductivity. The oxygen sensor with (Y0.08Sr0.92)(1-x)Ti0.8Cr0.2O3-delta dense diffusion layer show superior sensing performance with A-site deficiency level increasing. The relationship between logIL and 1000/T is obtained and the charge compensation mechanism is systematically discussed. The obtained results demonstrated that limiting current is nearly independent of temperature at high operating temperature. This paper provides a chemical strategy to enhance the mixed conductivity of oxygen sensors through Yand Cr-double doping and via a simple, low cost, and traditional sol-gel technique. (c) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.