ELECTRICAL PROPERTIES OF LANTHANUM OXIDE-CALCIUM OXIDE SOLID ELECTROLYTES

Electrical conductivity measurements have been made in the La2O3-CaO system as a function of composition, temperature, and oxygen pressure. At 1600°C, La2O3 can dissolve about 16 m/o CaO which leads to the creation of anion vacancies. These defect solid solutions behave as oxygen anion con ductors below an oxygen pressure of 10−7 atm. Above this pressure, the appearance of p-type conductivity, proportional to PO21/4, produces a region of mixed conduction. No evidence of n-type conductivity was observed. Even La2O3 exhibits predominantly ionic conduction at intermediate oxygen pres sures. Several transport numbers were verified by emf measurements. The results of this investigation are compared with those obtained previously for other oxide electrolyte systems. © 1969, The Electrochemical Society, Inc. All rights reserved.