Hydrothermal synthesis and sintering of electroceramics

The hydrothermal processing of ultrafine Pb-1.88(Zn0.3Nb1.25)O-5.305 and Ba (Mg0.33Nb0.67)O-3 powders as well as their sintering behavior at 1000 degre es C were investigated. The morphological analyses on nanometric powders in dicated the presence of mesopores in micrometric agglomerates with open cyl indrical pores. High dielectric constants were observed, showing normal fre quency dispersion and an intrinsic ac relaxation, relatively masked by low frequency conductivity. The sintered ceramics presented lower dielectric pe rmittivities than the hydrothermal powders, and a classical Cole-Cole plot could be obtained for the Pb-1.88(Zn0.3Nb1.25) O-5.305 electroceramic for f requencies above 10(3) Hz. (C) 1999 Elsevier Science Limited. All rights re served.