Papers by Author: Hao Xue

Abstract: Pure barium strontium titanate (Ba0.65Sr0.35TiO3) and MnO2-modified barium strontium titanate (Ba0.65Sr0.35TiO3-MnO2) thick films were fabricated by electrophoretic deposition technique. The structures and morphologies of the films were analyzed. The dielectric measurements were conducted on metal-insulator-metal capacitors using platinum as the bottom electrodes and gold as the top electrodes. The dielectric constants and dissipation factors of Ba0.65Sr0.35TiO3 and Ba0.65Sr0.35TiO3-15wt% MnO2 thick films were measured at a frequency of 1 MHz. The tunabilities of 12.5% and 9.3% were obtained for Ba0.65Sr0.35TiO3 and Ba0.65Sr0.35TiO3-MnO2 thick films under an applied electric field of 15 kV/cm, respectively. The dielectric properties of the present thick films were suitable for tunable microwave device applications.

Abstract: In this work, tape-casting technique was employed to prepare Ba0.7Sr0.3TiO3 films for lens antenna system. Effects of slurry properties on the tape casting procedure were investigated and the thickness, tensile strength and the surface roughness of the tapes were studied. The structure, morphology and the dielectric properties of the films were analyzed.

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.

Abstract: Ba1-xSrxTiO3 ceramic (BST) was one of the promising materials applied in phased array antennas due to its excellent dielectric properties. Ba1-xSrxTiO3 ceramic was prepared by traditional solid state reactions. Effects of different amount of ZrO2 as additive upon the dielectric properties of BST were investigated. The analyzed results showed that, as the amount of ZrO2 increasing, the dielectric constant and temperature dependence of dielectric constant of this ceramic both decreased, while its dielectric tunability kept high value.