ELECTRICAL-TRANSPORT IN RBCL-AL2O3 COMPOSITE SOLID ELECTROLYTES

The composite solid electrolytes RbCl-x mole percent (m/o) Al2O3 (0 le ss than or equal to x less than or equal to 50) prepared by convention al powder metallurgy and solution casting processes, have been investi gated by impedance analysis x-ray diffraction (XRD), differential ther mal analysis (DTA), and scanning electron microscopy (SEM). The compos ites prepared by the former method exhibit about an order of magnitude lower conductivity than those prepared by the latter technique. The X RD and DTA results show that no phases other than RbCl and Al2O3 are p resent in the composites. SEM results show that RbCl grains are inters persed with Al2O3 particles. The conductivity of dispersed systems dep ends on the processing, particle size, and concentration of Al2O3. The mechanism of enhanced conductivity is proposed to be the generation o f excess Rb+ ion vacancies in the host matrix at the matrix-particle i nterface. Macroscopically the results are explained satisfactorily on the basis of random resistor network model by assuming the formation o f high conducting space charge layer along the matrix-particle interfa ce.