To investigate the effect of aging at 580 °C in wet air (humid aging) on the oxygen adsorption on the surface of SnO₂ particles, the electric properties and the sensor response to hydrogen in dry and humid atmospheres for SnO₂ resistive-type gas sensors were evaluated. The electric resistance in dry and wet atmospheres at 350 °C was strongly increased by humid aging. From the results of oxygen partial pressure dependence of the electric resistance, the oxygen adsorption equilibrium constants (K₁; for O⁻ adsorption, K₂; for O²⁻ adsorption) were estimated on the basis of the theoretical model of oxygen adsorption. The K₁ and K₂ in dry and wet atmospheres at 350 °C were increased by humid aging at 580 °C, indicating an increase in the adsorption amount of both O⁻ and O²⁻. These results suggest that hydroxyl poisoning on the oxygen adsorption is suppressed by humid aging. The sensor response to hydrogen in dry and wet atmosphere at 350 °C was clearly improved by humid aging. Such an improvement of the sensor response seems to be caused by increasing the oxygen adsorption amount. Thus, the humid aging offers an effective way to improve the sensor response of SnO₂ resistive-type gas sensors in dry and wet atmospheres.

Co-sintering a cathode material and the Li₇La₃Zr₂O₁₂ (LLZ) electrolyte can assist in fabricating bulk-type all-solid-state batteries (ASSBs).

A co-fired solid-state battery based on Li _6.5 La _2.9 Ca _0.1 Zr _1.4 Bi _0.6 O ₁₂ + Li ₃ BO ₃ electrolyte.

In this study, the influence of the oxygen partial pressures (P_O2) on the sensor response to H₂ of SnO₂ resistive-type gas sensors was evaluated under various humid atmospheres. SnO₂ nanoparticles of 8–15 nm in diameter were synthesized using a hydrothermal technique followed by calcination at 600°C. Additionally, a large amount of pores with diameters greater than 10 nm was confirmed in the nanoparticles. The electrical resistance at 350°C was decreased with decreasing the P_O2, and the electrical resistance in the presence of 10 ppm H₂ was much smaller than that in the absence of H₂ in both dry and humid atmospheres regardless of the P_O2. Furthermore, the sensor response to 10 ppm H₂ at 350°C increased with decreasing P_O2 in both dry and humid atmospheres. Thus, decreasing the amount of oxygen adsorption enhanced the effect of rooted hydroxyl formation on the SnO₂ surface through a combustion reaction between H₂ and adsorbed oxygen and improved the sensor response to H₂. These results are important for understanding the fundamental mechanisms of gas detection and for the material surface design of highly sensitive resistive-type semiconductor gas sensors.