Features of behavior of solid-state CO<Subscript>2</Subscript> sensors at low temperatures

The dependence of the impedance of low-temperature sensors for carbon dioxide based on the solid-state electrochemical cells Na_0.5WO₃/Na₅GdSi₄O₁₂/SnO₂(Sb₂O₄) on the concentration of carbon dioxide in the air was studied. The reversible change in the sensor resistance was shown to be due to adsorption processes at intergrain boundaries of the solid electrolyte. The composition of the products of the electrochemical processes occurring in the sensors was established. Electronic Publication     

Conductivity and Morphology of Composite Solid Electrolytes SnO2· nH2O–Heteropolycompounds

The structure and surface characteristics of SnO₂ · 1.5H₂O and composite materials with heteropolycompounds (HPC) formulated as SnO₂ · 1.5H₂O–HPC (where HPC = (NH₄)₃PW₁₂O₄₀ · nH₂O, (NH₄)₂HPW₁₂O₄₀ · nH₂O, and H₃PW₁₂O₄₀ · nH₂O) are studied by scanning tunneling microscopy. Hydrated tin oxide is characterized by a globular structure which differs substantially from the morphology of composite materials. The conductivity is studied as a function of both the temperature and humidity of environment and the composition of composite materials. For composite materials containing ((NH₄)₂HPW₁₂O₄₀ · nH₂O, the conductivity is shown to vary monotonously with the composition and obey the mixture rule. Introduction of (NH₄)₃PW₁₂O₄₀ · nH₂O to a composite is found to cause an extremely fast conductivity decay, whereas addition of H₃PW₁₂O₄₀ · nH₂O results in the appearance of a plateau on the conductivity vs. composition curve. The explanation given to the phenomena observed is based on the mechanism of protonic transport in heteropolycompounds.