Li3Sc2-xFex(PO4)(3) thin films and powders prepared by ultrasonic spray pyrolysis

Thin films of Li3Sc2-xFex(PO4)(3) (x = 0.5, 2) solid electrolytes have been prepared on quartz glass substrates by ultrasonic spray pyrolysis (USP) us ing aqueous solutions of LiH2PO4, Sc(NO3)(3) and Fe(NO3)(3) at substrate te mperature of 500-700 degreesC. The amorphous as-deposited films were conver ted into crystalline materials by heat treatment at 800-1000 degreesC. The optimal deposition parameters for formation of uniform precursor films with good adhesion to the substrate were determined. The dense films composed o f fine columnar grains were obtained using the three cycles of deposition a nd annealing. The room temperature ionic conductivity of the film with the composition x = 0.5 was 5 x 10(-6) S/cm. The superionic gamma -phase of USP ceramics of Li3Sc2-xFex(PO4)(3) (0 < x less than or equal to 0.6) was show n to be stabilized at room temperature, which may be caused by slight struc tural distortions and changes in the interactions between the lithium ions during Sc3+--> Fe3+ substitution. The highest ionic conductivity sigma (25 degrees) approximate to 1 x 10(-5) S/cm was observed for ceramics with x = 0.4. (C) 2001 Elsevier Science B.V. All rights reserved.