The ex situ lift out (EXLO) adhesion forces are reviewed and new applications of EXLO for focused ion beam (FIB)-prepared specimens are described. EXLO is used to manipulate electron transparent specimens on microelectromechanical systems carrier devices designed for in situ electron microscope analysis. A new patented grid design without a support film is described for EXLO. This new slotted grid design provides a surface for holding the specimen in place and also allows for post lift out processing. Specimens may be easily manipulated into a backside orientation to reduce FIB curtaining artifacts with this slotted grid. Large EXLO specimens can be manipulated from Xe+ plasma FIB prepared specimens. Finally, applications of EXLO and manipulation of FIB specimens using a vacuum probe lift out method are shown. The vacuum probe provides more control for placing specimens on the new slotted grids and also allows for easy manipulation into a backside configuration.

A unique class of impurity-based quasi-liquid films has been widely observed at free surfaces, grain boundaries (GBs), and hetero-phase interfaces in ceramic and metallic materials (Figure 1). These nanometer-thick interfacial films can be alternatively understood to be: (a) quasi-liquid layers that adopt an “equilibrium” thickness in response to a balance of attractive and repulsive interfacial forces (in a high-temperature colloidal theory) or (b) multilayer adsorbates with thickness and average composition set by bulk dopant activities [1–2]. In several model binary systems, such quasi-liquid, interfacial films are found to be thermodynamically stable well below the bulk solidus lines, provoking analogies to the simpler interfacial phenomena of premelting in unary systems [3] and prewetting in binary de-mixed liquids [4]. These interfacial films exhibit structures and compositions that are neither observed nor stable as bulk phases, as well as transport, mechanical, and physical properties that are markedly different from bulk phases.

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Superplastic deformation was studied in fine-grained (0.7–1.1 μm) YBa2Cu3O7–x/Ag composites containing 2.5–25 vol% Ag. The compression tests were conducted in the temperature range of 750–875 °C and at strain rates of 10−5 to 10−3/s. For the YBa2Cu3O7−x/25%Ag composites with grain size of 0.7–1.1 μm, deformed at 800–850 °C and 10−5 to 10−3/s, the stress exponent, grain size exponent, and the activation energy of deformation were 2.0 ± 0.1, 2.5 ± 0.7, and 760 ± 100 kJ/mol, respectively. These values were the same as those of the pure YBa2Cu3O7−x, indicating that the deformation of the composite was controlled by that of the rigid YBa2Cu3O7−x phase. However, the strain rate was increased by the addition of silver as explained by the soft inclusion model of Chen. The dependence of the flow stress on the silver content was in close agreement with the prediction of the model.

Electron backscatter diffraction (EBSD) has been applied to characterize Pb(Mg1/3Nb2/3)O3–35 mol%PbTiO3 single crystals grown by the seeded polycrystal conversion method. Macroscopically triangular crystal growth fronts were shown to each be associated with discrete crystals that originated from slightly misoriented segments of an initially cracked single-crystal seed plate. Various types of crystal imperfections, including voids, second-phase regions, and polycrystalline matrix grains trapped within the grown region, were readily identified and distinguished from one another using EBSD. Further, it was shown that trapped matrix grains in the grown region had consistently small misorientations with respect to the grown single crystal and this may be qualitatively explained by a simple boundary energetics argument. The significance of the trapped grains is discussed.

The tensile creep behavior of yttrium- and lanthanum-doped alumina (at dopant levels below the solubility limit) was examined. Both compositions (100 ppm yttrium, 100 ppm lanthanum) exhibited a uniform microstructure consisting of fine, equiaxed grains. The creep resistance of both doped aluminas was enhanced, compared with undoped alumina, by about two orders of magnitude, which was almost the same degree of improvement as for materials with higher dopant levels (in excess of the solubility limit). In addition, measured creep rupture curves exhibited predominantly steady-state creep behavior. Our results, therefore, verified that the creep improvement in these rare-earth doped aluminas was primarily a solid-solution effect.

SrTiO3 was investigated as an alternate seed material to grow Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) ferroelectric single crystals by seeded polycrystal conversion. Fully dense polycrystalline samples of PMN–32 mol% PT doped with 3 vol% excess PbO were top-seeded with (111) SrTiO3 substrates. Annealing for 10 h at 1150 °C resulted in growth of PMN–32PT single crystals with sizes on the order of several millimeters. Orientation imaging microscopy confirmed that the grown crystal exhibited the same crystallographic orientation as that of the SrTiO3 seed. Elemental distributions analyzed using energy dispersive spectroscopy indicated that interdiffusi on of the relevant elements was negligible.

The RBAO (Reaction Bonded Aluminum Oxide) process and water-based gel casting were combined to produce alumina platelet reinforced RBAO composites. In the RBAO process, a precursor powder mixture of Al metal and Al2O3 is reacted to form 100% ceramic. To obtain composites in which the platelets are highly aligned, tapes consisting of 10 vol.% homogeneously distributed alumina platelets and 90 vol.% RBAO precursor powder were made by water-based gel casting using an extended doctor blade arrangement. Pellets of textured composites were subsequently prepared by stacking sheets cut from the green tapes, and filter pressing. Randomly oriented platelet composites were made using the same starting powders and gelling procedure, but without the tape-casting step. Reaction bonding was carried out in a box furnace in air. Microstructures of the composites were characterized using x-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of platelet orientation on contact damage behavior was studied using a Hertzian indentation method. It was found that the textured composite exhibited improved damage resistance compared to the random composite.

The variation of grain morphology in silver-doped YBa2Cu3O7−x was investigated as a function of sintering temperature, atmosphere, and amount of Ag addition. In the presence of the liquid phase formed at 925 °C for undoped samples, and at 910 °C for silver-doped samples, the grain shape and size changed drastically from small and nearly equiaxed to large and elongated. The anisotropy in the grain shape was sensitive to both the silver content and the atmosphere. On the other hand, while the grain size was generally insensitive to the atmosphere, it decreased as the silver content increased. The silver phase, if sufficiently large, would block the grain growth in the matrix. The amount of silver for effective blocking was predicted from a microstructural model, and the prediction was in agreement with experimental results.

The reaction between alumina and yttrium barium cuprate subjected to a melt-texturing heat treatment was studied. Microstructural examination of quenched, partially transformed samples revealed that at ∼1050 °C (which is above the incongruent melting temperature of YBa2Cu3O6+x) a reaction layer forms at the alumina interface. The reaction products were identified as Ba6Y2Al4O15 and a copper-rich liquid phase. On cooling below the peritectic temperature, aligned domains of YBa2Cu3O6+x (123) were observed to nucleate preferentially at the reaction layer. For samples of melt-textured 123 deliberately seeded with alumina particles, it was found that nucleation and growth of 123 occurred exclusively at the particles. A reaction sequence for the formation of the Ba6Y2Al4O15 is put forward, together with a discussion of the possible nucleation mechanisms for the 123.

Annealing of YBa2Cu_Og (12 3) above the peritectic temperature, followed by slow cooling at 0.5 C/min, was found to produce a microstructure containing regions (d ‐ 200 microns) within which the grains were highly aligned. When these regions were used to “seed” 123 powder, an enhanced degree of texture was obtained, where the aligned regions were > 1mm in size.