The intergranular films (IGFs) between the ceramics grains have very important effects on the structure and mechanical properties on the whole ceramics and have been studied for many decades. In the thesis, molecular dynamic (MD) computer simulations were applied to study the IGFs between the alumina and silicon nitride ceramic grains. Preferential adsorption of specific ions from the IGFs to the contacting surfaces of the alumina crystals was observed in the study of calcium-alumino-silicate glassy (CAS) IGFs formed between the combined basal and prism orientations of [alpha]-Al2O3 crystals. This segregation of specific ions to the interface enables formation of localized, ordered structures between the IGF and the crystals. However, the segregation behavior of the ions is anisotropic, depending on the orientation of the [alpha]-Al2O3 crystals. Self-diffusion of calcium ions between these CAS IGFs was also carried out by MD simulations. The results show that the diffusion coefficients adjacent to the interfaces are smaller and the activation energies are much higher than those in the interior of the IGF and in bulk glasses. It was also suggested that Ca transport is mainly though the interior of the IGF and implies that diffusion would be significantly inhibited by sufficiently thin IGFs. The growth of the alumina ceramic grains was simulated in the contacting with IGFs containing high concentrations of aluminum ions. Five different compositions in the IGFs were studied. Results show preferential growth along the [1120] of the (1120) surface in comparison to growth along the [0001] direction on the (0001) surface for compositions near a Ca/Al ratio of 0.5. The simulations also show the mechanism by which Ca ions in the IGF inhibit growth on the basal surface. The simulations provide an atomistic view of attachment onto crystal surfaces, affecting grain growth in alumina. The dissolution of the alumina crystal grains in the silicate melts is another important issue in the application of alumina ceramics. The simulations results showed that alumina grains dissolved into the melts homogeneously at very high temperatures. The orientation of the crystals and the compositions of the melts only take effect at some intermediate temperatures, to make the alumina grains dissolution anisotropic. The fracture phenomena of the pure silica IGFs between the basal silicon nitride crystals were studied by applying the constant tensile strain on the simulated IGF system, as well as for the bulk silica glass for the comparison. The data indicated that the fracture was happened in the interior of the IGFs and the thickness of the IGFs has important effect on the fracture stress/strain relationships.

Although ceramics have been known to mankind literally for millennia, research has never ceased. Apart from the classic uses as a bulk material in pottery, construction, and decoration, the latter half of the twentieth century saw an explosive growth of application fields, such as electrical and thermal insulators, wear-resistant bearings, surface coatings, lightweight armour, or aerospace materials. In addition to plain, hard solids, modern ceramics come in many new guises such as fabrics, ultrathin films, microstructures and hybrid composites. Built on the solid foundations laid down by the 20-volume series Materials Science and Technology, Ceramics Science and Technology picks out this exciting material class and illuminates it from all sides. Materials scientists, engineers, chemists, biochemists, physicists and medical researchers alike will find this work a treasure trove for a wide range of ceramics knowledge from theory and fundamentals to practical approaches and problem solutions.

One of the key technologies needed to understand and develop the mechanical and electrical properties of ceramics is the field of grain boundary engineering. This book covers new developments in this important field and addresses topics from grain boundary phenomena to grain boundary quantum structures, including the development of new techniques such as multifunctional electronmicroscopes, various kinds of spectroscopic analysis, and first principles calculations. Proceedings of the Japan Fine Ceramics Center Workshop, March 15-17, 2000, in Nagoya, Japan; Ceramic Transactions, Volume 118.

The thin intergranular phase in a silicon nitride (Si3N4)ceramic, which has been regarded for decades as having an entirely amorphous morphology, is shown to have a semi-crystalline structure. Using two different but complementary high-resolution electron microscopy methods, the intergranular atomic structure was directly imaged at the atomic level. These high-resolution images show that the atomic arrangement of the dopand element cerium takes very periodic positions not only along the interface between the intergranular phase and the Si3N4 matrix grains, but it arranges in a semi-crystalline structure that spans the entire width of the intergranular phase between two adjacent matrix grains, in principle connecting the two separate matrix grains. The result will have implications on the approach of understanding the materials properties of ceramics, most significantly on the mechanical properties and the associated computational modeling of the atomic structure of the thin intergranular phase in Si3N4 ceramics.

This book provides a state-of-the-art collection of recent papers on interfaces in heterogeneous ceramic systems presented at the 6th Pacific Rim Conference on Ceramic and Glass Technology (PacRim 6) in September of 2005 in Maui, Hawaii. The book is logically divided into 5 sections on interfaces, including theory and modeling, wetting phenomena, heterogeneous interfaces in high-temperature superconductors, bio-interfaces, and new developments in instrumentation that aid in the characterization of interfaces.

This thesis presents results from a combined atomic-resolution Z-contrast and annular bright-field imaging and electron energy loss spectroscopy in the Scanning Transmission Electron Microscopy, as well as first principles studies of the interfaces between crystalline β−Si3N4 and amorphous (i) CeO2-x as well as (ii) SiO2 intergranular film (IGF). These interfaces are of a great fundamental and technological interest because they play an important role in the microstructural evolution and mechanical properties of Si3N4 ceramics used in many high temperature and pressure applications. The main contribution of this work is its detailed description of the bonding characteristics of light atoms, in particular oxygen and nitrogen, at these interfaces, which has not been achieved before. The atomic-scale information on the arrangement of both light and heavy atoms is critical for realistic modeling of interface properties, such as interface strength and ion transport, and will facilitate increased control over the performance of ceramic and semiconductor materials for a wide-range of applications.