Transparent Ag nanowire arrays embedded in anodic alumina membranes were prepared by a template-based approach combined with ac electrodeposition and subsequent etching of substrate. The optical response of the structure could be attributed to surface plasmon resonance (SPR) of Ag nanowires. When the incident light was perpendicular to the surface of the composite film, only the transverse resonant mode was excited, and a dual peak line shape appeared at about 400nm in the optical absorption spectrum. The longitudinal resonance mode appeared at a longer wavelength when polarized light illuminated the film with an angle of incidence of about 70℃, where the angle was defined with respect to the surface normal. The resonant positions and relative intensities of the two resonant modes were affected by the diameter and aspect ratio of nanowires as well as the polarization direction of incident light. In contrast to the prediction of quasistatic theory, the longitudinal resonance peak did not red shift any more while the aspect ratio was large enough.

Composite materials containing both ferroelectric and ferromagnetic phases have been synthesized from nanometer-sized pow-ders of BaTiO3 (ferroelectric phase) and NiCuZn ferrite (ferromagnetic phase) by a standard ceramic method. The coexistence of magnetic and electric hysteresis in the composite material has been observed at room temperature. Upon the application of magnetic and electric fields, the magnetization and electric polarization of the composite material can easily be tuned based on the changing BaTiO3 content of the materials studied. These composite materials exhibit both xcellent dielectric and soft-mag-netic properties with a variation of the frequency. Our results strongly suggest that this composite material may be the best can-didate for the development of truly integrated passive filters. Due to the combination of both inductance and capacitance in one material, the adoption of an integrated passive filter could greatly reduce the size of printed circuit boards and could effi-ciently suppress electromagnetic interference, thereby enabling significant miniaturization of electronic elements and devices.

(Pb,La) (Zr,Ti)O3 (PLZT) inverse opal photonic crystals were synthesized by a process of self-assembly in combination with a sol-gel technique. In this process, PLZT precursors were infiltrated into the interstices of the opal template assembled by monodisperse submicron polystyrene spheres, and then gelled in a humid environment. Polystyrene template was removed by calcining the specimen at a final temperature of 700℃ accompanied with the crystallization of perovskite phase in PLZT inverse opal network. Scanning electron microscope images show that the inverse opals possess a fcc structure with a lattice constant of 250nm. A wide photonic band gap in the visible range is observed from transmission spectra of the sample. Such PLZT inverse opals as photonic crystals should be of importance in device applications.

We have investigated the structural and magnetic properties of a novel type of hexaferrite with composition of Ba3M2Fe23O41 (where M=Co and Mn) (Z hexaferrite) with tunable permeability. The material is promising for very high frequency (VHF) control when used in a voltage-controlled oscillator (VCO) as a tunable inductor. We substituted Mn for Co in the composition Ba3Co2 Mn Fe23O41 from X=0.0 to 1.2 to improve the inductance tunability and quality factor of the inductor material. Mn substitution had significant influence on the grain size of the sintered hexaferrites, and the coercivity was greatly reduced. The initial permeability and quality factor increased with increasing substitution of Mn for Co until reached 0.5, an effect attributed to the decrease of the magnetocrystalline anisotropy constant of the hexaferrite and increase of average grain size. The tunability of the samples also increased with increasing Mn substitution, reaching a maximum at X= 0.5, and then decreased with further substitution. This behavior is similar to that of the initial permeability and coercivity, and can be explained by the same mechanism.

We present a scheme for tuning the photonic band gap (PBG) by an external electric field in a ferroelectric inverse opal structure. The inverse opals, consisting of ferroelectric (Pb,La)(Zr,Ti)O3 (PLZT) ceramics, were synthesized by a sol-gel process. Optical reflection spectra show that the PBG of the PLZT inverse opals shifts continuously with the change in the applied electric field. As the photonic crystals (PCs) consist of the high-refractive-index constituent and possess an "all-solid" structure, it should supply a more reliable mode to tune the PBG by the electric field for the superprism effect in PCs. It should be of high interest in device applications.