A low-loss and near-zero temperature coefficient of resonant frequency (T f ) low-temperature cofired ceramic (LTCC) host dielectric was developed for portable consumer wireless device applications. The low T f was realized by compensating the Al 2 O 3 -filled-glass dielectric with admixtures of TiO 2 (negative temperature coefficient of dielectric constant (T )) in the starting formulation. XRD data indicated a portion of the TiO 2 in the starting formulation dissolved into the glass, and extensive formation of crystalline titanium compounds was observed via a nucleation and growth mechanism. The dissolution of TiO 2 in the glass and subsequent formation of titanium compounds was believed to result in the relatively small amount of TiO 2 required to achieve a near-zero T f in the final sintered structure.

Recent advances in the development of microplasma devices fabricated in a variety of materials systems (Si, ceramic multilayers, and metal/polymer structures) and configurations are reviewed. Arrays of microplasma emitters, having inverted pyramidal Si electrodes or produced in ceramic multilayer sandwiches with integrated ballasting for each pixel, have been demonstrated and arrays as large as 30×30 pixels are described. A new class of photodetectors, hybrid semiconductor/microplasma devices, is shown to exhibit photoresponsivities in the visible and near-infrared that are more than an order of magnitude larger than those typical of semiconductor avalanche photodiodes. Microdischarge devices having refractory or piezoelectric dielectric films such as Al 2 O 3 or BN have extended lifetimes (∼86% of initial radiant output after 100 h with an Al 2 O 3 dielectric) and controllable electrical characteristics. A segmented, linear array of microdischarges, fabricated in a ceramic multilayer structure and having an active length of ∼1 cm and a clear aperture of 80 × 360 µm 2 , exhibits evidence of gain on the 460.3 nm transition of Xe + , making it the first example of a microdischarge-driven optical amplifier.

The diversity of applications for spherical materials, often referred to as hollow or solid microspheres, microballoons, shells and microcapsules, span a wide range of technologies and attracts the talents of individuals from a broad set of disciplines. Consequently, this knowledge and capability is widely dispersed. A prime objective of this symposium was to bring that diverse community together to share, for mutual benefit, that knowledge and capability. This article highlights some of these diverse technologies and applications and identifies some of the many important literature sources encountered.

The devitrification kinetics and mechanism of a low-dielectric, low-temperature, cofirable K 2 O-CaO-SrO-BaO-B 2 O 3 -SiO 2 glass-ceramic have been investigated. Crystalline phases including cristobalite (SiO 2 ) and pseudowollastonite ((Ca,Ba,Sr)-SiO 3 ) are formed during firing. Activation energy analysis shows that the nucleation of the crystalline phases is controlled by phase separation of the glass. The crystallization kinetics of both cristobalite and pseudowollastonite obey Avrami-like behavior, and the results show an apparent activation energy close to that of the diffusion of alkaline and alkali ions in the glass, suggesting that diffusion is rate limiting. The above conclusion is further supported by analysis of measured growth rates.