Ultra-thin Al2O3−Sr(1−x)GdxTiO3 composite ceramics with high microwave absorption performance

Abstract

Gadolinium (Gd)-doped perovskite SrTiO3 combining with Al2O3, Al2O3−Sr(1−x)GdxTiO3 (x varying from 0 to 0.3 in steps of 0.1) composite ceramics was synthesized by hot-press sintering in a vacuum. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS), four-probe testing instrument, and vector network analyzer were utilized to study their phase and composition characteristics, micromorphology, electrical conductivity, electromagnetic and microwave-absorbing properties, respectively. The XRD, SEM, and EDS results demonstrated that Gd atoms were successfully doped into SrTiO3 crystal and substituted the Sr sites. As a result, Al2O3−Sr(1−x)GdxTiO3 with x = 0.2, which has the advantage of an ultra-thin thickness (0.341 mm), exhibits excellent absorbing properties with a broad bandwidth (90% microwave absorption) of 4.07 GHz in the X band. Furthermore, the present investigation illustrated that Al2O3−Sr(1−x)GdxTiO3 (x = 0.1, 0.2, and 0.3) could be applied in the X band for microwave absorption, with broadband width and ultra-thin thickness (≤ 0.35 mm), by controlling the molar ratios of Gd and the thickness.