This article considers the fundamentals of what happens in a solid when it is impacted by a medium-energy gallium ion. The study of the ion/sample interaction at the nanometer scale is applicable to most focused ion beam (FIB)–based work even if the FIB/sample interaction is only a step in the process, for example, micromachining or microelectronics device processing. Whereas the objective in other articles in this issue is to use the FIB tool to characterize a material or to machine a device or transmission electron microscopy sample, the goal of the FIB in this article is to have the FIB/sample interaction itself become the product. To that end, the FIB/sample interaction is considered in three categories according to geometry: below, at, and above the surface. First, the FIB ions can penetrate the top atom layer(s) and interact below the surface. Ion implantation and ion damage on flat surfaces have been comprehensively examined; however, FIB applications require the further investigation of high doses in three-dimensional profiles. Second, the ions can interact at the surface, where a morphological instability can lead to ripples and surface self-organization, which can depend on boundary conditions for site-specific and compound FIB processing. Third, the FIB may interact above the surface (and/or produce secondary particles that interact above the surface). Such ion beam–assisted deposition, FIB–CVD (chemical vapor deposition), offers an elaborate complexity in three dimensions with an FIB using a gas injection system. At the nanometer scale, these three regimes—below, at, and above the surface—can require an interdependent understanding to be judiciously controlled by the FIB.

Silicon carbide (SiC) fibers made by chemical vapor deposition (CVD) are of interest for organic, ceramic, and metal matrix composite materials due their high strength, high elastic modulus, and retention of mechanical properties at elevated processing and operating temperatures. The properties of SCS-6™ silicon carbide fibers, which are made by a commercial process and consist largely of stoichiometric SiC, were compared with an experimental carbon-rich CVD SiC fiber, to which excess carbon was added during the CVD process. The concentration, homogeneity, and distribution of carbon were measured using energy dispersive x-ray spectroscopy (SEM/EDS). The effect of excess carbon on the tensile strength, elastic modulus, and the crystallographic and microstructural properties of CVD silicon carbide fibers was investigated using tensile testing, x-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

Composite Ag-SiO2 thin films were deposited to examine the stability of materials with high resistivity above 5000 μΩ-cm. We found that the resistivity increases exponentially with SiO2 volume fractions larger than 0.50 which is consistent with a tunneling conductivity mechanism. In order to obtain a broad composition range, these films were deposited on a stationary substrate placed above Ag and SiO2 sputtering sources. This configuration allowed compositions ranging from 0.8 to 56.3% SiO2 to be deposited on the same sample. Resistance measurements were made using a four-point probe and a profilometer was used to measure thickness. Predicted values of thickness and composition were obtained by calibrating deposition rates from the separate sources, and were verified using Rutherford Backscattering Spectroscopy. Electron microscopy analysis revealed Ag agglomerating on the surface of the film. Because of the high mobility of Ag, the films should be capped to prevent Ag agglomeration. The results of this research demonstrate that high-resistivity thin films can be grown using Ag-SiO2 composites.

Boron fibers made by a commercial chemical vapor deposition (CVD) process have been used as precursors for the formation of magnesium diboride (MgB2) superconducting wires. Prior to a reaction with magnesium, the addition of dopants such as carbon and titanium to the boron fiber has been shown to enhance the superconducting properties of MgB2. These dopants also influence the kinetics of the reaction with magnesium. In this study, the effect of carbon dopant additions on the microstructure of boron fibers was investigated using powder x-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Additionally, bundles of boron fibers were pressure infiltrated with molten magnesium and reacted at elevated temperatures. The microstructure and microchemistry of the fiber-metal interfaces were investigated by TEM and energy dispersive x-ray analysis (EDS).

Chemical vapor deposited (CVD) silicon carbide (SiC) ceramic material was joined to itself via an air stable, silver-based active brazing alloy (ABA). The microstructure and microchemistry of the interface was characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Results were compared to previous studies on the active alloy brazing of sintered silicon carbide using higher copper alloys.

Circumferential mechanical texture (scratches) of hard drive substrates has improved head/media tribology; however, it has also been advantageous to the development of OR (Orientation Ratio) for longitudinal media. The magnetic dipoles prefer to circumferentially align with texture, which matches the direction heads read/write. The corrugated nature of films sputtered on fine texture scratches leads to an anisotropic stress state in the films, especially for those deposited at temperatures above ambient; and OR has been attributed to this anisotropic stress. A review article discusses possible causes of the OR such as: self-shadowing due to the texture lines during deposition, circumferential c-axis alignment, shape anisotropy of media grains, and magnetostrictive effects. Another work listed two requirements for OR: <> Co crystallographic growth texture in addition to circumferential texture scratches. The same study considered frequencies and depths of the texture scratches, and concluded that OR increased as the ratio of depth/frequency increased, rather than just as a function of Ra alone.

Hard drives in portable computers require media deposited on glass substrates and employ NiAl as the first seed layer to optimize magnetic performance. From observations of a 112 XRD peak [1], a <112> texture has been reported to develop as sputtered films of NiAl thicken; however, synchrotron analysis observes additional cubic peaks [2]. The electron diffraction in this study detects no dominant <112> orientation in NiAl, but rather that the NiAl films (and subsequent cubic underlayers) are closer to 3-D isotropic. Furthermore, the +/-20° range of ﹛1100﹜ orientations observed [3] in the Co media grains grown on NiAl/Cr occurs not because of one (or two) special zone axis relationship(s), nor due to substrate surface finish, but rather as a consequence of multiplicity relationships between the cubic and hexagonal crystals. Although an “increase” in variants is often accepted for an upper film (e.g. bicrystals of [1120] Co on [200] Cr),

TEM provides fast and statistical support for magnetic recording media development. Turn-around time including sample preparation, data collection and computer analysis is reduced to ∼3 hours. Rapid, systematic TEM analysis is shown to accurately measure crystallographic Orientation Ratio (OR) on mechanically textured media by diffraction analysis; elucidate grain separation by Weak Beam Dark Field Imaging; and determine the crystallographic relationship between cubic-NiAl seed layers and hexagonal cobalt-alloy (Co) layers. Novel evidence for reduction of the number of preferred orientations in sequentially grown epitaxial films is presented, which explains the “2-&-1/4-D isotropic” growth orientation and the high magnetic squareness of Co media grown on nearly randomly oriented “3D-isotropic” NiAl underlayers.

The crystallization of glass ceramics provides processing advantages for difficult shapes. Machining and sintering are limited to produce complex parts; similarly (superplastic) forming is limited to special ceramics. In theory, however, a liquid (or glass) may be simply poured into any shape, and then crystallized (or partially crystallized) to provide a strong, tough ceramic. In this work, a thin layer of glass ceramic, cordierite (2MgO.2Al2O3.5SiO2), joins SiC [1]. Tailoring secondary phases and percent crystallization provide flexible control of the coefficient of thermal expansion to minimize strain mismatches between the joint components.

Three processing steps are involved in crystallization of glass ceramics: first a fast quench produces the initial glass; the second step is a lower temperature “nucleation” anneal, where phase separation and/or precursors and/or the final structure is nucleated and ideally as a fine dispersion; the third step is the higher temperature “crystallization” anneal, where renucleation and/or growth develops a homogeneous (ideally fine grained) final crystalline product [2, 3].