Structural and dielectric properties of Y2O3-doped Ba0.92Sr0.08Ti0.95Sn0.05O3 ceramics

Abstract

Abstract：The structural and dielectric properties of Ba 0.92 Sr 0.08 Ti 0.95 Sn 0.05 O 3 (BSTS)+x(molar ratio, %)Y 3+ ceramics are investigated. Combining the lattice parameters and the distortion of crystal lattice, an alternation of substitution preference of Y 3+ ion for the host cations in perovskite lattice is found. Owing to Y 3+ ion entering the A site, the maximum dielectric constant is 5 627 for 1.25% Y 3+ -doped samples; when Y 3+ ion is more than 1.25%, it tends to occupy the B site in perovskite lattice, causing a drop in the dielectric constant. Owing to the appearance of oxygen vacancy, the optimized dielectric loss is 0.004 for 1.25% Y 3+ -doped samples. The thermal stability of BSTS ceramics is significantly improved and the Curie temperature shifts to lower value with the amount of Y 2 O 3 increased, making it a superior candidate for capacitor applications.In recent years, materials with a high dielectric constant and lead-free compositions have attracted much interest for environment-friendly applications. BaTiO 3 -based ceramics is widely used in the manufacture of thermistors and multilayer ceramic capacitors(MLCC) owing to their high dielectric permittivity. The perovskite type BaTiO 3 -based ceramics such as barium strontium titanate(Ba 1-x Sr x TiO 3 , BST)has received extensive attention because of their predominant properties of dielectric behavior and phase transition. In order to obtain excellent dielectric properties such as higher dielectric constant, lower dissipation factor, adjustable Curie temperature, thermal stability and other properties, much effort has been made by the way of substitution for the host cations in perovskite lattice. It has been well documented [1][2][3][4][5][6] that small amounts of impurity ions can dramatically modify the properties of BST ceramics in general. The influence of rare earth dopants such as La 2 O 3 [7,8] , Nb 2 O 5 [9-16] , Dy 2 O 3 [17] , Y 2 O 3 [18,19] on the dielectric properties of BST has been widely researched. Sn-doped BaTiO 3 -based ceramics exhibits paraelectric or ferroelectric properties depending on its specific composition and temperature. In addition, the nonlinear dielectric property of Sn-doped BaTiO 3 -based ceramics makes it attractive to electrically tunable microwave devices [20,21] . The Y 2 O 3 -doped Ba 0.92 Sr 0.08 Ti 0.95 Sn 0.05 O 3 (BSTS)ceramics is described in this paper as superior candidates for lead-free ferroelectric materials to reduce environmental damages, and it was prepared by conventional solid state method. The yttrium ion as dopant was added to improve the dielectric properties. The lattice parameters were calculated through X-ray diffraction (XRD) analysis. The microstructural and dielectric properties of all specimens were investigated for capacitor applications. ExperimentThe general formula of the materials was BSTS+ xY 3+ , where x=0-1.75% (molar ratio). The samples were prepared with the two-stage method to acquire a pure phase of perovskite. In the first stage, the carbonate and oxide powder of...

β-Blocker and Other Analogous Treatments that Affect Bone Mass and Sympathetic Nerve Activity in Ovariectomized Rats

“…The effects were nearly comparable to propranolol at 150 µg/kg. These results demonstrate that Fcs should be act as a β-blocker (Wang, 1982;Wang et al, 1997). No further study regarding similar central depressant actions with propranolol up to date stimulated us to explore the role of Fcs in the control of bone mineral metabolism or bone turnover in osteoporotic rats from the point of the sympathetic nervous system.…”