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The effects of BaCu(B2O5) (BCB) addition on the microstructure, phase formation, and microwave dielectric properties of Ba5Nb4O15−BaWO4 ceramic are investigated. As a sintering aid, BaCu(B2O5) ceramic could effectively lower the sintering temperature of Ba5Nb4O15−BaWO4 ceramic from 1100 °C to 950 °C due to the liquid-phase effect. Meanwhile, BaCu(B2O5) addition effectively improves the densification of Ba5Nb4O15−BaWO4 ceramic and significantly influences the microwave dielectric properties. X-ray diffraction analysis reveals that Ba5Nb4O15 and BaWO4 coexist with no crystal phase of BaCu(B2O5) in the sintered ceramics. The Ba5Nb4O15−BaWO4 ceramics with 1.0 wt% BaCu(B2O5) sintered at 950 °C for 2 h presents good microwave dielectric properties of εr = 19.0, high Q×f of 33802 GHz and low τf of 2.5 ppm/°C. [ABSTRACT FROM AUTHOR]

The effects of the addition of H3BO3 on the microstructure, phase formation, and microwave dielectric properties of (Zn0.7Mg0.3)TiO3 ceramics sintered at temperatures ranging from 890 °C to 950 °C are investigated. H3BO3 as a sintering agent can effectively lower the sintering temperature of ZMT ceramics below 950 °C due to the liquid-phase effect. The microwave dielectric properties are found to strongly correlate with the amount of H3BO3. With the increase in H3BO3 content, the dielectric constant (εr) monotonically increases, but the quality factor (Q × f) reaches a maximum at 1 wt% H3BO3, and the apparent density of ZMT ceramics with H3BO3 ≥ 1 wt% gradually decreases. At 950 °C, the ZMT ceramics with 1% H3BO3 exhibit excellent microwave dielectric properties: εr = 19.8, and Q × f = 43800 GHz (8.94 GHz). [ABSTRACT FROM AUTHOR]

Dielectric-coated metallic hollow fiber (DMHF) is an increasingly popular fiber for the delivery of terahertz (THz) wave. There is a need for small-diameter fibers in a variety of THz wave applications. Transmission characteristics of DMHF with subwavelength diameter in the THz region are numerically investigated. The effective refractive indices, attenuation constants, and power distributions are presented. The effect of the metal layer on enhancing the modal field confinement is demonstrated by comparing the power distribution of the fiber to that of the polymer tube. Attenuation dependence on the dielectric layer is studied concerning the layer thickness and the refractive index. Both the optimal thickness and the optimal refractive index for the dielectric layer are dependent on the core size. Fiber with a smaller core requires a thicker dielectric layer and lower dielectric refractive index to achieve low attenuation. The results are important to the design of subwavelength diameter DMHF for the transmission of THz waves. [ABSTRACT FROM AUTHOR]

A systematic study of the charge transport and electrical properties in poly(3-hexylthiophene) (P3HT) polymer layers is performed. We demonstrate that the temperature-dependent current-voltage J(V, T) characteristics of hole-only devices based on P3HT can be accurately described using the recently introduced extended Gaussian disorder model (EGDM). A particular numerical method adopting the uneven discretization and Newton iteration method is used to solve the coupled equations describing the space-charge limited (SCL) current in conjugated polymers. For the polymer studied, we find the width of the density of states σ = 0.1 eV and the lattice constant a = 1.15 nm. Based on the numerical method and EGDM, we further calculate and analyze some important electrical properties for P3HT in detail, including the variation of current-voltage characteristics with the boundary carrier density and the distribution of charge-carrier density and electric field with the distance from interface. [ABSTRACT FROM AUTHOR]

Polycrystalline Fe3O4 films grown on different thicknesses of Fe underlayers were prepared by dc reactive-magnetron sputtering in an Ar+O2 gas mixture and annealing under an infrared-lamp furnace system. Analyses of structural and magnetic properties revealed that a 15 nm Fe underlayer can be oxidized to Fe3O4 by increasing the oxygen flow rates during initial Fe3O4 layer growth. These analyses also confirmed the stoichiometry and high-crystallographic quality of grown Fe3O4. Adopting this method, Fe3O4 films can be grown without any other elemental buffer layers. [ABSTRACT FROM AUTHOR]