Papers by Author: Ji Wei Zhai

Abstract: The dc bias and temperature dependence of dielectric properties of Pb1-xBaxZrO3 (PBZ) thin films with higher x (x=0.6, 0.7, 0.8 and 1) were investigated in detail. The results indicated that Pb0.4Ba0.6ZrO3 films possessed a moderate tunability of 32.3% and a higher figure of merit of 53.8, which were measured at 100 kHz and at room temperature. Moreover, Pb0.4Ba0.6ZrO3 films exhibited a smaller temperature coefficient of capacitance TCC-20-90= -1390 ppm/oC.

Abstract: xMnCO3–(1–x)[70wt% (10wt% MgO–90wt% Ba0.4Sr0.6TiO3)–30wt% MgAl2O4] (where x=0.0, 0.5, 1.0, 2.0, 5.0 and 10.0wt%) composite ceramics have been prepared through the solid-state reactions. Three phases, corresponding to the Ba0.4Sr0.6TiO3(BST), MgAl2O4(MA) and MgO phases, are clearly visible in the composite ceramics. The permittivity peak is initially enhanced and shifted toward a higher temperature and then suppressed, shifted toward a lower temperature. Meanwhile, the tunability (calculated by [ε(E0)−ε(E)]/ε(E0)) is also initially improved and then decreased by doping MnCO3.

Abstract: The effect of 9Bi2O3-CuO mixed oxides as sintering agent on sintering behaviors and dielectric properties of Ba0.6Sr0.4TiO3 (BST) ceramics were investigated. It was found that 9Bi2O3-CuO mixed oxides lowered the sintering temperature about 300°C and that highly denser BST ceramic pellets were obtained by sintering at 975oC with addition of 5.0-10.0wt% mixed oxides. For BST ceramics with 5.0wt% CB content sintered at 975°C, had a moderate dielectric constant (ε=1315), low dielectric loss (0.0067) and high tunability (36%) at dc electric field of 20kV/cm and at room temperature and at 10kHz.