Effects of CaO–B2O3 glass addition on the low-temperature sintering and cation ordering in SrxLa(1−x)TixAl(1−x)O3 ceramics

Abstract

SrxLa(1−x)TixAl(1−x)O3 (SLTA, x=0.4–0.7) ceramics with additive of CaO–B2O3 glass (1–10wt%) were prepared by a solid-state reaction process, which led to a significant decrease in sintering temperature, from 1550°C to 1100°C. Dielectric properties of ceramics at low frequency were significantly improved by CaO–B2O3 glass addition, especially the obtained dielectric loss ∼6×10−4 at room temperature and 1MHz. Superlattice reflection was detected in the prepared oxides by X-ray diffraction (XRD), selected area electron diffraction (SAED) and Raman spectra, indicating presence of cation ordering. Meanwhile, lattice images of high-resolution transmission electron microscopy (HRTEM) also certificated the presence of cations ordering. Notably, the detected superlattice reflection in perovskite structure associated with antiparallel A-site cation displacements and anti-phase octahedral tilting. This ordered structure as well as low temperature sintering both affected the microwave dielectric properties of Sr0.7La0.3Ti0.7Al0.3O3 ceramics, which exhibited with ɛr∼43.3, Q×f∼10,780GHz and τƒ∼20.8ppm/°C. The smaller cations doped in A site, a larger difference in ionic radius or cation valence of B-site cations were considered to primarily facilitate the formation of cation ordering, which promoted microwave dielectric properties of the ceramics.