The citrate-gel processing of electronic and magnetic ceramics

The use, advantages and disadvantages of the citrate-gel route for the production of electronic and magnetic ceramics are discussed. Particular examples selected to illustrate the major points are lead zirconate titanate (PZT) and soft magnetic spinels. It is shown that the citrate gel route can yield complex ceramics of an excellent chemical homogeneity at temperatures much lower than used in conventional mixed oxide ceramic processing. The oxide powders are shown to be of fine, uniform particle size which allows sintering to give uniform fine-grained microstructures. Magnetic properties of spinel oxides of the Mn-Zn system produced by the citrate gel route will be presented and discussed in terms of the microstructures obtained in sintered products. For situations where a stronger complexing agent is required for gel production it is shown that EDTA (ethylenediaminetetraacetic acid) can be substituted for the citric acid