Giant dielectric response in (Li, Ti)-doped NiO ceramics synthesized by the polymerized complex method

This paper reports on the synthesis of nanocrystalline (Li, Ti)-doped NiO powders (i.e., Li0.3Ti0.02Ni0.68O, abbreviated as LTNO) by the polymerized complex (PC) method. The synthesized LTNO powders were characterized by thermogravimetric-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The powders, with particle sizes of 39, 65 and 72 nm as estimated from XRD, were sintered in air at 1280 degrees C for 4 h to obtain bulk LTNO ceramics. A giant dielectric constant of 10(4)-10(5) at low frequency with weak temperature dependence over the measured temperature range (-30 to 160 degrees C) was observed in the sintered LTNO ceramics. The origin of the high permittivity observed in these LTNO ceramics is attributed to the Maxwell-Wagner polarization mechanism and a thermally activated mechanism. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.