Lead oxide rich grain boundary

On increasing the content of Ca in the anode alloy, a product that seems to be mainly an oxide was observed at the grain boundaries on the anode surfaces after 3 h of electrolysis. With the increase in the content of Ca in the anode material, the thickness of the oxide layer increases after 20 days electrolysis time therefore, the presence of Ca in the anode was considered to lead to a rapid covering of the anode surface by the Pb02 oxide layer. Also, the reaction of the oxide layer is closely related to the presence of the CaPb3 and Ag-rich phases at the grain boundaries. 

The variety of mixed conductors is also very high and is associated with their applications in solid oxide fuel cells as electrode materials. The addition of the transition metal oxides to these conductors limits the decrease of the total conductivity and maintenance of its ionic nature. Further doping leads to a separation of a transition metal oxide phase inducing a correlative decrease of the ionic conductivity and an increase of the electronic conductivity, especially at low temperatures. Mixed conductivity was observed only in transition metal oxide phases and electronic conductivity in the zirconia-rich parts of the binary and ternary systems. The phase separation of a transition metal oxide starts at the ceramic grain boundaries. Then, the second phase forms grains and cross-linked structures, and the conductivity approaches to that of the pure transition metal oxide. The enhancement of the solid solubility of the transition metal cations with the increase of the temperature is characteristic of most studied ternary systems. When the concentration of the stabilizing dopant is changed, the... 

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