High permittivity of Ba(Ti_(1-x)Zr_x)O_3-based Y5V-type nanopowders and ceramics synthesized using a one-step sol-gel method

摘要

We synthesized Ba(Ti_(1-x)Zr_x)O_3-based (BTZ) nanopowders modified with Cu and Nb, and sintered ceramics using a one-step sol-gel process. Characterization using TG-DTG, XRD, SEM, and TEM analysis methods revealed that the powders formed at a nanometer scale. The process was controlled by the composition and calcining temperature. BaZrO_3 formed earlier than BaTiO_3 during the calcining, then a Ba(Ti_(1-x)Zr_x)O_3 solid solution formed incompletely, resulting in ceramics with huge permittivity and good temperature stability. Moreover, the maximum dielectric constant (ε_(max)) first increased and then decreased as the Curie temperature (T_c) shifted to a lower temperature. When the Zr concentration was 5.4 mol%, ε_(max) was greater than 24,000 and the dielectric loss (25℃) was only 0.005; this meets the Electronic Industries Alliance Y5V specifications. These nanopowders would permit a significant reduction in the thickness of multilayer ceramic capacitors and the huge permittivity of the ceramics will help meet the current demand for device miniaturization in the electronics industry.