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

• Limiting current oxygen sensors are fabricated using Y, Cr codoped SrTiO 3. • Sol-gel method and ((Y 0.08 Sr 0.92) 1- x Ti 0.8 Cr 0.2 O 3−δ) as novel dense diffusion barrier are used. • The impact of A-site deficiency on total electrical and ionic conductivities is studied. • The charge compensation mechanism and temperature independency are discussed. • Mechanism of mixed conductive is studied using oxygen ionic and total conductance. A-site-deficient Y, Cr doubly doped SrTiO 3 ((Y 0.08 Sr 0.92) 1- x Ti 0.8 Cr 0.2 O 3−δ (x = 0.01, 0.03, 0.05)) powders were synthesized via sol–gel method, followed by sintering at 1450 °C at ambient condition. The phase composition, mixed conductivities, and sensing performance are characterized to identify the influence of A-site deficiency on the Y- and Cr-doubly doped SrTiO 3. The ionic conductivity and total conductivity of (Y 0.08 Sr 0.92) 1-x Ti 0.8 Cr 0.2 O 3−δ 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 (Y 0.08 Sr 0.92) 1-x Ti 0.8 Cr 0.2 O 3−δ dense diffusion layer show superior sensing performance with A-site deficiency level increasing. The relationship between log I L 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 Y- and Cr-double doping and via a simple, low cost, and traditional sol–gel technique. [ABSTRACT FROM AUTHOR]

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