Boron nitride thin films have been deposited on (100) oriented Si substrate by magnetically enhanced activated reactive evaporation technique. The build up of c-BN is normally accompanied by strong compressive stresses. When these stresses exceeds the strength of the adhesion forces at the interface, adhesion fails causing the destruction of the c-BN film. This has been one of the major limiting factors of using the c-BN films for many important industrial applications such as cutting tools and semiconductor devices.

In this experiment, the plasma immersion ion implantation has been applied to improve the adhesion of the film. The post ion implantation was conducted at several implantation energies and constant dose. The effect of ion implantation on the microstructures was investigated by Fourier Transform Infrared spectroscopy and Transmission Electron Microscopy.

Infrared characterization of c-BN film by FTIR (Fig.l) shows that the IR spectra of the specimens prepared at all energies but 72 kV have strong absorption band at 1080 cm-1 corresponding to cubic boron nitride.

Silicon carbide composites are known for high-temperature strength retention, creep resistance, high elastic modulus and light weight. Laminated matrix composites (LMC's) with a matrix of alternating layers of silicon carbide (SiC) and carbon (C) with carbon fiber reinforcements possess added toughness in addition to the desirable properties of SiC composites mentioned above. The improved toughness results from both the laminated matrix, which offers a tortuous path to crack propagation, and the energy expended in fiber debonding during fracture. Microstructural analyses of LMC's are necessary to help the processing effort to achieve structures with the desired properties. In this work, a preliminary examination of the microstructure of the laminated matrix composite is undertaken using TEM.

Specimens for TEM examination were prepared by cutting slices from a bulk sample of ∼ 1 mm thickness with a low-speed diamond saw. The slices were then ground to no less than 200 μm thickness to prevent the slices from breaking.

Aluminum nitride, translucent, calcia-sintered and hot pressed, with its superior thermal properties has applications in high performance electronic devices such as multichip modules. In these applications, A1N is exposed to high energy electromagnetic sources which could alter its properties; for example, upon UV irradiation, thermal conductivity drops and dielectric loss increases. These observations indicate that the UV altered properties are due to the presence of impurities. The early studies concentrated primarily on oxygen doped samples, which photodarken upon UV exposure; the role of other impurities was not considered.

In the current work, we consider the role of carbon in the microstructure of two very low oxygen content (< 0.3 wt %), carbon-containing samples, labeled B and E, for the ultimate purpose of 3 determining the mechanism by which carbon impurities affect the properties of A1N. Previous work on these samples correlated higher carbon content with a lower increase in the dielectric loss factor, after UV irradiation,

Magnetoresistance describes a phenomenon in which the electrical resistance of the material depends strongly on an externally applied magnetic field. Colossal magnetoresistance (CMR) was observed in a new class of oxides, (La,A)MnO3 (A = Ca, Sr, or Ba), and the Magnetoresistance ratio of ΔR/R(H)> -100,000% has been reported in epitaxially grown La0.67Ca0.33MnO3 films. The new types of intrinsic magnetoresistive oxides offer exciting possibilities for improved magnetic sensors, magnetoresistive read heads, and magnetoresistive random access memory (MRAM).

The CMR magnetic oxides have a perovskite-type crystal structure with ferromagnetic ordering in the a-b planes and antiferromagnetic ordering along the c-axis (Figure 1). The ferromagnetically ordered Mn-O layers of the a-b planes are isolated by a non-magnetic La(A)-O monolayer. This spin-coupling structure is intrinsic. La1-xAxMn03 compounds having the extreme values x = 0, 1 are neither ferromagnetic nor good electrical conductors; they are semiconductors. Only compounds with intermediate values of x are ferromagnetic,

A perovskite manganese oxide of Bi0.2Ca0.8MnO3 exhibits charge ordering of Mn3+ and Mn4+ ions upon cooling. This is an interesting phenomenon from both academic and practical viewpoints, since the charge ordering is accompanied by significant changes in both electric and magnetic properties of the oxide. Since a difference of scattering amplitudes between Mn3+ and Mn4+ is quite small, charge ordering can be observable as superlattice reflections due to the lattice strain caused by this ordering with an electron diffraction method. However, the background in an electron diffraction pattern, which is mainly caused by plasmon scattering, has hindered a precise investigation of the weak diffuse scattering. The purpose of the present work is to assess an efficiency of an omega-type energy-filter in detailed observations of the weak superlattice reflections associated with the charge ordering.

Specimens of Bi0.2Ca0.8MnO3 were prepared by a conventional ion-milling technique. The critical temperature of charge ordering (TCo) was determined to be 160K by resistivity and magnetization measurements.

Ferroelectric superlattices have been actively and intensively studied in recent years for their great scientific and technological interest. Superlattice containing Pb-based ferroelectric layers are important among ferroelectric superlattice systems, however, it is difficult to grow such superlattice due to the high volatility of Pb. Recently, great progress has been made in fabricating superlattice structure of PbZrO3/PbTiO3 by multi-ion-beam sputtering’ and molecular beam epitaxy (MBE). In this paper, we report the microstructural investigations of PbTiO3/SrTiO3 superlattice films, which were epitaxially grown on the SrTi03 substrate by MBE, using transmission electron microscopy (TEM).

[(PbTiO3)l0/(SrTiO3)l0]15 superlattice films were stacked on (100) SrTiO3 substrate alternately by MBE. Before growing the superlattice structure, a baffle layer including the 1000Å La-doped SrTi03 and the subsequent 500 Å PbTiO3 thin films was grown on the substrate. Above the PbTi03/SrTi03 superlattices, another PbTi03 thin film (1000 Å) was grown. Cross-section TEM specimens were prepared by standard methods.

Epitaxial thin film of SrRuO3 is very useful in device applications, due to its important electrical and magnetic properties. For example, (Pb,Zr)TiO3 ferroelectric capacitors with SrRuO3 thin film electrodes exhibit superior fatigue and leakage characteristics. Epitaxial SrRuO3 thin films grown on different substrates, such as on (001) SrTiO3 and (001) LaA1O3, have different magnetic properties, owing to the different microstructures in the film. Microstructures in epitaxial SrRuO3 thin films grown on (001) SrTiO3 have been studied in our previously work. In this paper, microstructure of epitaxial SrRu03 thin films grown on (001) LaA103 is reported.

SrRuO3 thin films on (001) LaA1O3 were deposited by 90° off-axis sputtering. For cross-section TEM studies the SrRuO3/LaA1O3 heterostructural samples were cut along the [100] direction of LaA103. The cut slides were glued face-to-face by joining the SrRu03 surfaces. Plan-view and cross-section TEM specimens were prepared by mechanical grinding, polishing and dimpling, followed by Ar-ion milling.

It is widely believed that the stress in the epitaxial thin films, caused by the lattice mismatch between the thin film and substrate, has a strong influence on the properties. For example, lattice strained epitaxial thin films of SrRu03 grown on (001) SrTiO3 demonstrated magnetic and electrical properties different from those in bulk materials.1 In this paper, we report the effect of strain relaxation of the thin film on microstructure by means of transmission electron microscopy (TEM).

SrRuO3 thin film on a vicinal (001) SrTiO3, with a miscut angle 0.9° and miscut direction 5.7° away from the in-plane [100] axis, was grown by 90° off-axis sputtering. Cross-section and plan-view TEM specimens were prepared following the procedure described in Ref. 2. TEM investigations were conducted in a Philips CM 12 microscope in the EMAL at the University of Michigan.

X-ray diffraction studies of the as-grown SrRu03 thin film using a four-circle diffractometer showed that the film consists of a single [ 110]-type domain structure.

The perovskite structure is based upon the mineral CaTiO3, which is a pseadocubic at room temperature. The ideal structure has a twelve fold coordinate A-site, and an octahedral coordinated B-site, and the face-centered position being oxygen. The perovskites have been of commercial interest for capacitors owing to their high dielectric constants. The crystal chemistry related to the perovskite based dielectrics multilayer capacitors (MLCs) is of interest in this paper. The MLCs with base metal internal electrodes such as copper and nickel have been studied for many years. To avoid oxidation of the nickel or copper electrodes during sintering, a reducing atmosphere is necessary. However, reduced firing causes two basic problems: an increasing of conductivity of the BaTiO3, dielectrics and limitation on reliability by the migration of oxygen vacancies. The solution for the first problem is to use acceptor dopants, such as MnO and more stable oxide additives, such as CaZrO3 to increase the resistivity of the dielectrics.

Achieving superplasticity in fine-grained ceramics is a potential method to lower energy costs associated with ceramic manufacturing via net shape forming. Superplasticity is intrinsic in 3-mol%- yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP), and can be enhanced by addition of glass to form intergranular phases which are thought to both limit grain growth and promote grain boundary sliding during processing (sintering and hot isostatic pressing). This permits processing at lower temperatures. However, superplasticity has not been observed in 8-mol%-yttria-stabilized cubic zirconia (8Y-CSZ), ostensibly due to its larger grain size and high grain growth rates.3,4 As part of a larger study, high-spatial-resolution energy-dispersive X-ray spectrometry (EDS) has been performed on 3Y-TZP and 8Y-CSZ specimens doped with various glassy phases to characterize intergranular compositions.

Zirconia powders were mixed with glass to produce specimens having either 1 wt % lithiumaluminum- silicate, 1 wt % barium-silicate, or 1 wt % borosilicate. Some specimens were prepared without added glass.

EELS is a powerful analytical tool for exploring the local solid state environment in materials. There is an extensive literature on EELS analysis of the transition elements and light elements, yet few EELS data exist for heavy elements with multiple oxidation states. We report here on EELS studies of oxidation state influences on near-edge structure in cerium and uranium compounds.

All materials analyzed for this study were embedded in low viscosity epoxy and TEM specimens prepared using ultramicrotomy. The thin sections (∼50 nm thick) were analyzed using a JEOL 2010 (200kV) TEM operated with a LaB6 filament and equipped with a GAT AN 666 parallel EELS spectrometer. EELS data were collected in image mode at 105X magnification with a collection semi-angle of ∼ 100 milliradians at a dispersion of 0.1 eV/channel. The full width at half maximum of the raw (unprocessed) zero-loss peak was 0.7 eV. Peak positions were calibrated by applying a known voltage to a drift tube.

Metal-ceramic composites possess a wide range of applications due to an increased fracture toughness and strength compared to monolithic materials. A better understanding of the correlation between properties and microstructure of these materials requires a detailed analysis of the phases which form during processing. This can be accomplished by using various transmission electron microscopy (TEM) methods. In this study Nb based AI2O3 composites were investigated. The composites were prepared by pressureless sintering 2 of compacts of attrition milled AI2O3 and prealloyed Nb(Al) powder mixtures. The addition of 7 wt.% of Al to the Nb powder is supposed to assist in rapid and complete sintering of the material. The microstructure was studied in detail by conventional TEM using selected area diffraction (SAD). The chemistry and structure of the occurring phases, second phase particles and grain boundaries were analysed by analytical TEM and high resolution TEM (HRTEM).

Silicate glasses are the most common constituents of intergranular phases which can be found in liquid-phase sintered ceramics [1]. Silicates are known to influence the structure of ceramic interfaces which, in turn, frequently affect mechanical properties of ceramic materials [2]. In earlier studies of silicate glasses on single-crystal alumina Ramamurthy et al [3] and Mallamaci [4] showed that the morphology of dewetted glass films and the mechanism of devitrification depend on the crystallographic orientation of the substrate surface. In continuation of these studies, results are presented on the dewetting behavior of monticellite (CaMgSi04) in contact with the (OOl)-oriented surface of single-crystal MgO. Due to the simplicity of sample preparation and availability of 3- dimensional topographic information, Atomic Force Microscopy (AFM) was used for surface characterization. These AFM results are complemented by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) data on the chemical composition and the structure of the glass-substrate interface.

Crystallization of intergranular glass films can influence the performance of ceramic materials [1]. The crystallization of anorthite glass films has been studied in situ in the transmission electron microscope (TEM) [2]. The films are grown by pulsed-laser deposition (PLD) on sapphire (α-AI2O3) substrates. These substrates can be pre-thinned to electron transparency, so that contamination or microstructural damage of the TEM specimen due to the thinning process can be eliminated. This process also allows the microstructure of the glass films to be characterized before crystallization; the evolution of specific features of the film can then be tracked through repeated heat treatments. Prior to the crystallization of the anorthite glass films, observations confirmed that all the glass films deposited by PLD are indeed amorphous. Crystallization experiments were performed in a Philips CM30 TEM equipped with a Gatan single-tilt heating holder. Each specimen was heated in the microscope to a temperature of about 1200 °C at a heating rate of about 30 °C/min. and held at this temperature for 20 minutes.

It is well known that diffusion in ionic materials occurs primarily by the movement of charged species. Therefore, an applied electric field can provide a very large driving force for mass transport. In the present study, thin films of In2O3 and Fe2O3 have been deposited on (001) and (111) MgO using pulsed-laser deposition (PLD). These thin-film diffusion couples have then been reacted in an applied electric field at elevated temperatures. The electric field directly influences the diffusion of the cations in the constitutive layers. Through the use of both transmission (TEM) and scanning (SEM) electron microscopy, diffusion couples reacted either with and without an electric field have been analyzed to examine the effect that an induced ionic current can have on solid-state reaction processes.

The apparatus for reacting the diffusion couples in a field has been described elsewhere. The diffusion couples were characterized in cross-section by SEM and TEM techniques.

HRTEM images of α-Al2O3 oriented along [1100] often exhibit a modulation of the basal fringe intensity with a period that corresponds to twice the basal plane spacing. In the example shown in figure 1, note the strong basal fringe contrast in the A12O3 with a period of 4.33 Å. HRTEM image simulations for ideal imaging conditions fail to reproduce this doubling of the lattice fringe period. Instead, simulated images predict that the (0006) fringes (d0006=2.17 Å) should be of equal intensity (e.g., see Figure 3a). Incorrect beam and/or crystal tilt can strongly affect HRTEM image contrast. In particular, anomalous periodicities can arise under beam and crystal tilt conditions for which normally kinematically and dynamically forbidden diffracted beams contribute to the image. More recently, the importance of 3-fold astigmatism on HRTEM imaging has been recognized. As with beam tilt, this lens aberration produces asymmetrical phase shifts in the diffracted beams.

Layer silicates are important and abundant minerals. Polytypic details can be determined directly from atomic-resolution images recorded down [010] of layer silicates such as chlorite (Fig. 1), serpentine, and micas using a transmission electron microscope with a point resolution of ∼ 0.2 nm. For chlorite, this involves determination of whether octahedral slants in the brucite-like interlayers and octahedral sheet of the tetrahedral - octahedral-tetrahedral (TOT) layers are the same or opposed, the (3 angle, and how the octahedral cations in the brucite-like interlayer are positioned relative to the tetrahedral cations in the TOT layer (Fig. 1). Images must be recorded from the thinnest areas in order to distinguish slant of the brucite-like interlayer (composition dependent, but always < 0.7 nm sample thickness; 1). Polytype analysis is aided significantly by rotational filtering of images from thin areas to remove the amorphous contribution (2). All six of the common, semi-randomly stacked chlorite polytypes can be distinguished (1).

Since its invention inl982 scanning probe microscopy (SPM) has become an important analytical tool in every branch of physical science. The two most widely used types of SPM are atomic force Microscopy (AFM) and scanning tunneling microscopy (STM). Both AFM and STM allow measurement of the microtopography of a surface down to the atomic scale. Many spin-off applications such as lateral force and magnetic force allow measurement of a variety of the physical properties of a surface while imaging its microtopography. SPM can be done in both air and liquid and hence can be used to observe the interactions that take place at a solid-solution interface.

SPM has been used in mineralogy and geochemistry since 1989. Here as in other applications the great strength of SPM is in the characterization of the heterogeneous nature of mineral surfaces and the ability to observe many geochemical processes in real time.

Meteorites are remnants of the primordial material from which the solar system condensed. Most meteorites originated in the asteroid belt between Mars and Jupiter and fell to earth when their orbits were disturbed by collisions. Metal phases are present in all types of meteorites and are alloys of Fe and Ni containing S and P. The study of metal meteorites has yielded valuable information about the early thermal history of the solar system, since their heat treatment has been preserved in the microstructure and microchemistry of the meteorites and can be discerned by electron microscopy and microanalysis. A full understanding of the structure and chemistry of meteorites requires detailed knowledge of the Fe-Ni, Fe-Ni-S and Fe-Ni-P phase diagrams and determination of these diagrams has been carried out over more than three decades of electron-beam analysis by the authors.

The martian meteorite ALH84001 leapt into the spotlight in late 1996 when a NASA-led research team suggested that it contained evidence of biotic activity on ancient Mars. ALH84001 is unique among the martian meteorites- a cumulate rock made up predominantly of orthopyroxene, with interstitial maskelynite (feldspar turned into a diaplectic glass by shock), apatite, chromite and sulfides. Highly brecciated fracture zones cut through the rock, presumably a result of impacts, and within these zones is a variable amount of secondary carbonate. This carbonate, the most extensive secondary mineral found in any martian meteorite, formed during significant interaction between martian crust and volatiles, and represents a unique access point toward understanding the environment of ancient Mars. However, the conditions under which this carbonate formed are less clear. While claims for evidence of biotic activity are predicated on carbonate formation at low (<100°C) temperatures under water-rich conditions, other research suggests much less hospitable conditions, with little water present and formation temperatures approaching 700°C.