Abstract
xAl2O3–(1 − x)Sr0.85Gd0.15TiO3(x = 0.2, 0.3, 0.4, 0.5) ceramics were fabricated by hot-press sintering. Their phase composition, morphology, element compositions, conductivity, dielectric properties as well as microwave absorption performance were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), multifunction digital four-probe meter and vector network analysis, respectively. The microwave absorption of the as-prepared xAl2O3–(1 − x)Sr0.85Gd0.15TiO3 ceramics demonstrates excellent microwave absorbability. It is unexpectedly found that with a thickness of only 0.346 mm, xAl2O3–(1 − x)Sr0.85Gd0.15TiO3 (x = 0.2) ceramic exhibits an absorption bandwidth of 3.7 GHz (8.7–12.4 GHz), being consequential to reflection loss less than − 10 dB (over 90% of microwave absorption). It is as well discovered that the minimum reflection loss and absorption peak frequency of xAl2O3–(1 − x)Sr0.85Gd0.15TiO3 (x = 0.3) with a thickness of 0.436 mm were − 45.43 dB and 11.3 GHz, respectively. The prominent microwave absorption performance of the ceramic with such a thin thickness can be attributed to strong interfacial polarization, dielectric frequency dispersion, and good electromagnetic impedance matching. It indicates that the xAl2O3–(1 − x)Sr0.85Gd0.15TiO3 ceramics with appropriate Al2O3 mass fraction and thickness showing good potential for effective microwave absorbing materials.
Highlights
With the speedy evolution of science and technology in the defense industry, the demands of electromagnetic microwave absorbing materials that can effectively reduce the reflection of electromagnetic waves at high temperature in a required frequency range are urgent [1,2,3,4]
XAl2O3-(1-x)Sr0.85Gd0.15TiO3 ceramic materials with ultra-thin and excellent microwave absorption properties provide an attractive option for electromagnetic wave absorption applications
XAl2O3-(1-x)Sr0.85Gd0.15TiO3 ceramics were prepared by hot-press sintering
Summary
With the speedy evolution of science and technology in the defense industry, the demands of electromagnetic microwave absorbing materials that can effectively reduce the reflection of electromagnetic waves at high temperature in a required frequency range are urgent [1,2,3,4]. Some researchers have demonstrated the electromagnetic and microwave absorption properties of SrTiO3/Al2O3 complex ceramics [22, 23]. The microwave absorbing property of rare earth element doped-SrTiO3/Al2O3 has not been reported previously. Gd doped SrTiO3 with different contents of Al2O3 were combined as ceramic composite absorbing material using hot-pressed sintering method. The influence of Al2O3 content on the microstructure, dielectric behavior, electrical properties, and microwave absorption performances was studied. In order to obtain high density ceramics, they were prepared by hot-press sintering at 1350°C under 30 MPa for 2 h with a graphite mold in vacuum. The as-prepared complex ceramics were cooled down followed by furnace cooling to room temperature in the vacuum hot pressing sintering furnace
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