Spark Plasma Sintering of Core-Shell Structured (Mg,Zn)O Wrapped Ba_(1-x)Sr_xTiO_3 Nanopowder

摘要

Ba_(0.75)Sr_(0.25)TiO_3-Mg_(0.9)Zn_(0.1)O (BST-MZO) composite ceramics were prepared by sintering core-shell structured nano-powders at 1200℃ via a spark plasma sintering (SPS) process. X-ray diffraction measurements revealed the coexistence of two phases (BST and MZO). Scanning electron microscope analysis indicated that the ceramic had a pore-free microstructure and an average grain size of ～400 nm. The dielectric constant and loss tangent of the ceramic were 607 and 1.2 x 10~(-4) at 10 kHz at room temperature, respectively. A good dielectric tunability was observed in the ceramic. At room temperature, the tunability and the figure of merit of the ceramic were 65.78% and 300 (under a dc bias of 19.27 kV/cm), suggesting that the ceramic is a good candidate for tunable microwave devices.