Microwave dielectric properties of the layered functionally graded materials (FGMs) ceramics with Mg0.93Ca0.07TiO3 (MCT) and (Ca0.3Li0.14Sm0.42)TiO3 (CLST) were investigated as a function of sintering times at 1350 degreesC. The stable and uniform interfaces of the FGMs specimens were confirmed by X-ray diffraction and SEM photographs study. As a sintering time increased, Qf values of the FGMs specimens were decreased, whereas dielectric constants of the specimens did not changed remarkably. The change of Qf values could be attributed to the compositional inhomogeneity at the interfacial region resulted from the active ionic diffusion. From the EPMA work, active diffusion of Mg2+ (r = 0.72 Angstrom) and Ti4+ (r = 0.605 Angstrom) was detected in the interface of FGMs specimens with an increase of sintering time. (C) 2002 Elsevier Science B.V. All rights reserved.