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The effects of calcination time and sintering temperature on the properties of Ca[Cu.sub.3][Ti.sub.4][O.sub.12] are examined. Results suggest the complete formation of a single-phase of Ca[Cu.sub.3][Ti.sub.4][O.sub.12] by calcination at 750 degree Celsius for 12 hours.

Research describing parametric phase conjugation of ultrasound waves is presented. Increased average output power by means of multifrequency operation of the phase conjugator is demonstrated.

The authors propose a low-cost, relatively simple resonance testing to measure the new parameters for electroactive materials. A pair of coupling parameters can, with this method, characterize the material's electromechanical quality.

Microhardness profiles were used to monitor the density at BSCCO/Ag wires' and tapes' transverse cross sections after several deformation processes. Results provide an explanation of the deformation process and indicate the type of deformation is ideal for developing homogeneous and dense BSCCO-core through the powder-in-tube method. Results also stress the importance of optimal core density values in achieving high transport currents.

Photoemission spectroscopy was used in studying the surface properties of CuBa2Ca3Cu4O12-delta superconducting ceramics. Ultra-high vacuum annealing at temperatures below 150-degrees celsius was conducted to enhance the materials' surface electronic structure for applications in high performance contacts. A contact resistivity as low as 1x10(super -8) ohmcm2 was achieved using the approach.

A study was conducted on the fracture resistance and microstructural properties of superconductive ceramics. A computer model for crack bridging processes was employed in analyzing three types of restraining bridges, namely, frictional ligaments, elastic connections and tractions caused by thermal expansion anisotropy. An evaluation was then performed on the effects of initial press-powder porosity on certain crack bridging parameters.

Bulk samples of (Bi,Pb)2Sr2Ca2Cu3O10 were sintered for different times and then isothermally pressed at 850-degrees celsius under a constant pressure of 15 MPa for 1 hour. Critical temperature, mass density and critical current density were measured using EDS, XRD and scanning electron microscopy. The removal of voids in the materials under pressure and high temperature resulted in a significant increase in mass density.

Microwave sintering of ceramics in multimode cavities, particularly the use of picket-fence arrangements, has recently received considerable attention. Various types of ceramics have been successfully sintered and, in some cases, a desirable and unique 'microwave effect' has been observed. At present, various aspects of the sintering process such as preparation of sample sizes and shapes, types of insulations, and the desirability of including a process stimulus such as SiC rods are considered forms of art and highly dependent on human expertise. The simulation of realistic sintering experiments in a multimode cavity may provide an improved understanding of critical parameters involved and allow for the development of guidelines towards the optimization of the sintering process. In this paper, we utilize the FDTD technique to model various geometrical arrangements and material compatibility aspects in multimode microwave cavities and to simulate realistic sintering experiments. The FDTD procedure starts with the simulation of a field distribution in multimode microwave cavities that resembles a set of measured data using liquid crystal sheets. Also included in the simulation is the waveguide feed as well as a ceramic loading plate placed at the base of the cavity. The FDTD simulation thus provides realistic representation of a typical sintering experiment. Aspects that have been successfully simulated include the effects of various types of insulation, the role of SiC rods on the uniformity of the resulting microwave fields, and the possible shielding effects that may result from excessive use of SiC. These results as well as others showing the electromagnetic fields and power-deposition patterns in multiple ceramic samples are presented.

The magnetic properties of nanocrystalline FeHfC single layered and FeHfC/ceramics (AlN, [Al.sub.2][O.sub.3], [Si.sub.3][N.sub.4], Si[O.sub.2]) multilayered films were investigated. The soft magnetic properties of the multilayered films laminated by the Al-based ceramics were better, but those of films laminated by the Si-based ceramics were worse than the magnetic properties of single layered films. An analysis of multilayered structure revealed that FeHfC/AlN and FeHfC/[Al.sub.2][O.sub.3] films maintained better periodic structure than FeHfC/[Si.sub.3][N.sub.4] and FeHfC/Si[O.sub.2] films. The present results suggest that the interdiffusion effect plays an important role in determining the magnetic properties of the multilayered films.

Ferroelectric properties of 9% mol (Hf,Zr)-doped BaTi[O.sub.3] ceramics have been studied by comparison with those of pure tetragonal BaTi[O.sub.3] ceramics. The addition of doping ions lead to a shift of the rhombohedral to orthorhombic and orthorhombic to tetragonal transition temperatures above 0 [degrees] C, and to a decrease of tetragonal to cubic (ferroelectric to paraelectric) transition temperature from 122 [degrees] C to 95 [degrees] C on heating and from 120 [degrees] C to 85 [degrees] C on cooling. In pure tetragonal ceramics at room temperature, aging develops by a thermally activated process, leading to a linear dependence of the relative permittivity and dielectric loss on the logarithm of time. In case of doped ceramics, the experiments showed a decreasing reversed-S dependence of capacitance and tan [Delta] on the logarithm of time, suggesting that dielectric aging in these materials is related with defect diffusion. It was concluded that in doped BaTi[O.sub.3] ceramics the aging mechanisms depend on the crystalline symmetry, which influences the twinning process and the domain-wall dynamics. Aging of (Hf,Zr)-doped BaTi[O.sub.3] ceramics depends on temperature and the phase symmetry, which imposes the twinning rate and the rearrangement speed of ferroelectric domains minimizing the elastic energy of the lattice.

This paper outlines a method of tuning a microwave broadside coupler buried in the low-temperature co-fired ceramic. Etching a slot in the exposed ground plane tunes the characteristic impedance [Z.sub.0] of a stripline coupler. An iterative method computes the correct dimensions of the slot. Applying the method salvages microwave circuits detuned due to manufacturing tolerances. Index Terms--Co-fired, low temperture, Multilayer ceramic, stripline coupler.