Effect of various doping on electrochemical properties of KNbO3 proton conductor

KNbO3 and KNb0.9M0.1O3-& alpha; (M = Ti, Hf, Zr, Sc, In, Yb) were prepared by solid state reaction at 920 degrees C for 4 h and characterized by X-ray diffraction. The electrical properties of solid electrolytes were measured by AC impedance in wet air, wet Ar and dry Ar. The order of conductivity in different atmospheres is & sigma;(wet air)>& sigma;(wet Ar)>& sigma; (dry Ar). Among KNb0.9M0.1O3-& alpha; (M = Ti, Hf, Zr, Sc, In, Yb), KNb0.9In0.1O3-& alpha; displays the highest conductivity. The carriers transport numbers of each material were measured by concentration cell method. The results show KNb0.9In0.1O3-& alpha; is almost a pure proton conductor below 625 degrees C. KNb0.9In0.1O3-& alpha; has excellent chemical stability against CO2 and H2O, but in the process of use should avoid rapid heating and cooling.

Automated summary

KNbO3 and KNb0.9M0.1O3-α (M = Ti, Hf, Zr, Sc, In, Yb) were synthesized and characterized for their conductivity. Among them, KNb0.9In0.1O3-α showed the highest conductivity. The conductivity order in different atmospheres was wet air > wet Ar > dry Ar. KNb0.9In0.1O3-α was found to be a nearly pure proton conductor below 625°C. It also exhibited excellent chemical stability against CO2 and H2O, but should be used with caution to avoid rapid heating and cooling.