Papers by Author: Chun Lai Xu

Abstract: Ba0.5Sr0.5TiO3 (BSTO) ceramics were synthesized by spark plasma sintering (SPS) technique. The phase compositions, microstructure and dielectric properties of BSTO ceramics were investigated. The results indicated that SPS was an alternative sintering technology to synthesize dense BSTO ferroelectric ceramics at low temperature and in a short period.

Abstract: The influence of La2O3-doping on the dielec- tric properties of Ba0.6Sr0.4TiO3-6wt%MgO was studied. With the increase of La2O3-doping content, the space between adjacent parallel crystal planes of BST-MgO composite first became larger, then smaller. Proper quantity of La2O3 could ensure moderate dielectric constant and reduce the dielectric loss of BST-MgO composite at high frequency, but excess quantity of La2O3 would lower dielectric constant. When the La2O3-doping content was 0.2wt%, the dielectric constant and loss of BST-MgO composite were equal to 93.2 and 0.005 (1MHz), respectively. And the dielectric constant tunability could be obtained to 12.1% (21kV/cm).

Abstract: In this paper, a microwave material (Ba0.85Ca0.15)0.5Sr0.5TiO3 with 5 wt% MgO additive was prepared by traditional solid-state reactions, i.e., mixing BaTiO3 and SrTiO3 powders and then doping CaTiO3 and MgO. It was found that, with the increasing CaTiO3 content, the dielectric constant of the resultant material decreases and the tunability and dielectric loss increase.

Abstract: Barium strontium titanium oxide (BSTO) has great advantages and potentiality for the application of microwave technology. In order to be used in phased array antennas, high dielectric tunability, relatively low dielectric constant and low dielectric loss are required. In this paper, MgO was mixed into BSTO and the microstructure and dielectric properties of MgO-mixed BSTO bulk ceramics were investigated. The mole ratio of Ba and Sr was rather fixed to 5:5 in this study. It is observed that a small amount of MgO (5 wt%) has gone beyond the solubility limits of Mg in BSTO. The dielectric constant and dielectric loss of BSTO ceramics decreased with the increase of the content of MgO mixed. However, the tunability of MgO-mixed BSTO ceramics decreased at the same time. 20wt% MgO-mixed BSTO ceramics exhibits preferable dielectric properties with acceptable tunability.