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A correlation between the DC magnetization and hyperthermia heating rate in high frequency magnetic fields was established for two distinctively different magnetic nanoparticle (MNP) systems: (1) polystyrene (PS)/Fe 3 O 4 based composites, consisting of 10 nm diameter Fe 3 O 4 nanoparticles embedded in the matrix of polystyrene (PS) spheres (~100 nm), and (2) similar Fe 3 O 4 nanoparticles coated with polyacrylic acid (PAA) and dispersed in water. Due to physical confinement of Fe 3 O 4 nanoparticles in the former, the PS/Fe 3 O 4 composite exhibited much lower magnetic hyperthermia heating compared to the latter. The reduced magnetic hyperthermia heating in the polystyrene (PS)/Fe 3 O 4 based composites was found to be associated with strong dipolar interactions.

The dielectric properties of lead lanthanum zirconate titanate (PLZT) thin films are investigated on different combinations of bottom electrode (Pt, LaNiO 3 ) and substrate (Ni, Si). The results indicate strong effects of electrode on the permittivity and dielectric loss of these PLZT thin-films capacitors. The substrate-induced thermal strain has a great impact on the temperature dependence of the dielectric behavior. Based on these findings, dielectric applications using PLZT thin films in a wide range of temperature are possible by selecting appropriate electrodes and substrates.

Superparamagnetic nanorings of polystyrene/Fe3O4 composite were synthesized by miniemulsion polymerization. The nanoring structure was characterized by using transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. The results of X-ray diffraction identified the magnetic constituent of as-synthesized composite nanorings as Fe3O4. The magnetization measurement showed typical superparamagnetic characteristics of polystyrene/Fe3O4 nanorings.

Reaction of Y 2 O 3 , BaCo 3 and CuO for 4 h at 800 °C in flowing O 2 with a total pressure of about 2.7 × 10 2 Pa, followed by cooling in O 2 at ambient pressure, has produced phase-pure orthorhombic YBa 2 Cu 3 O x . Keeping the ratio of O 2 to evolved CO 2 above 50 was necessary to ensure phase purity. The resultant powder yielded pressed and inserted pellets with improved superconducting properties.

Grain boundaries in zone-melted YBa 2 Cu 3 O x have been studied in detail by means of transmission electron microscopy. Tilt and twist types of low-angle grain boundaries have been observed, which are composed of both edge and screw dislocations. These boundaries possess high crystal coherence and intimate contact. The low-angle boundaries are also found to be free of second phases. Direct dc transport critical current density, J c , at 77 K shows great improvement in the zone-melted sample compared with that of a conventionally sintered sample. The relationship between the enhanced J c and the low-angle grain boundaries is dicussed.

Heating of YBa 2 Cu 3 O 7− x compacts above about 930°C is shown to induce liquid formation. Presence of the liquid phase results in excellent densification, but limited superconducting properties. Sintering below 930°C occurs primarily by solid-state diffusion. Although the density of these samples is low, the superconducting properties are similar to those of the dense materials produced via liquid-phase sintering. The highest current densities (≈ 500 A/cm 2 ) have been obtained in these solid-state sintered samples.

A “powder-in-tube” technique was used to produce long superconducting wires. Calcined YBa2Cu3O7−δ powder was put into a copper tube and swagged down to wire of approximately 0.7 mm in diameter. The copper sheath was then removed chemically and the superconductor core was sintered in oxygen at 910°C. The critical current densities at 77 K and zero field were comparable to those of other bulk specimens, typically ranging from 200 to 600 A/cm2.

YBa2Cu3O7−x was synthesized by mixed-oxide reaction of Y2O3, BaCO3, and CuO. The starting constituents were mixed, followed by multiple steps of calcination with interposed grinding. Heating rapidly to 900°C was shown to minimize formation of liquid during calcination while still producing a phase-pure powder. Slow heating to 900°C or fast heating to 950°C resulted in formation of a liquid phase deleterious to YBa2Cu3O7−x synthesis.

Thin tapes of YBa2Cu3O7−δ superconductor have been tape cast by the doctor blade technique. X-ray diffraction studies showed that the (00l) planes of these tapes, to a modest degree, became preferentially aligned parallel to surface of the tape. This modest degree of preferential alignment resulted in a significant increase in measured critical current density.