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The effect of the anisotropic connectivity within the layers of the post-perovskite, CaIr[O.sub.3], structure are examined using a Rigid Unit Mode and group theory approach, and possible commensurate tilt structures ate given. It is shown that the anisotropic bonding of the sheet may give rise to preferred directions of buckling for such structures and anisotropy in the speed of sound. Keywords: Post-perovskite, CaIr[O.sub.3], tilt modes, layer structures, buckling modes, acoustic anisotropy

Hybrid inorganic-organic layered compounds are a broadly ranging and widely studied class of solids. The first systematic examination of the effects on the layered structure of simple silver aryl-monosulfonates as the breadth of the pendant aryl group is increased beyond that where a simple 'phosphonate-like' motif is sustainable is presented.

Long-lived charge separated state induced by visible light via guest-to-host electron transfer is revealed in cyanine dye/layered titanate intercalation compounds where the J-aggregates of the cyanine dyes effectively acted as sensitizers. The stability of the charge separated state is rationalized by slow electron diffusion in the conduction band of the hosts as well as the nanostructure of the intercalation compounds.

Photothermal beam deflection studies were carried out with GaAs epitaxial double layers grown on semi-insulating GaAs substrates. The impurity densities in thin epitaxial layers were found to influence the effective thermal diffusivity of the entire structure. OCIS codes: 120.4290, 160.6000, 300.6430, 310.6870.

The fabrication of a functional part requires very high layer quality in the Fused Deposition (FD) processes. The constant deposition flow rate currently used in FD technology cannot meet this requirement, due to the varying geometries of the layers. To achieve a high quality functional part, an overfill and underfill analysis is conducted. A deposition planning approach is proposed, which is based on a grouping and mapping algorithm. Two piezoelectric test parts have been built to demonstrate the effectiveness and feasibility of the proposed approach. [DOI: 10.1115/1.1455026]

Research demonstrates that ground and excited states of solids and clusters, composed of many-electron systems, can reliably be studied using variational and fixed-node diffusion quantum Monte Carlo techniques. Data show that properties of surfaces and defects and electronic correlation in real materials can be analyzed.

A finite element approach for predicting transient responses of layered structures to low-velocity impact is presented. Data demonstrate that both thickness and modulus ratios have effects on the impact response and influence structural damping of the flexural wave propagation.

In perhaps the first nontrivial application of an alternative interfacial compatibility condition, the elasticity solution of a circular three-layer sandwich ring under two forces acting along a diameter is obtained. Within each layer, the material property is linearly elastic and isotropic. The difficulty in treating the concentrated load at the outer boundary is overcome by using a solid disk solution in combination with a general series solution. A parametric study is carried out to quantitatively establish the beneficial effects in the mechanical sense of adding the cover layers to the core layer. The solution is applicable to sandwich pipes used in wastewater systems. The solution is also useful in providing a benchmark for numerical methods to compare with.

In this paper, we develop methodologies for the integration of layered manufacturing and traditional material removal processes into an integrated manufacturing setup. The scenarios under which this integration would be beneficial are identified and algorithms for the integration developed. As examples, we consider two current layered manufacturing technologies that use material removal operations as a part of their process. The benefits of our procedure are demonstrated by examples.

Analysis of the GaN layers grown without GaN buffer reveal high structural quality mirrorlike GaN layers. Data indicate that the layers are under strong tensile strain with biaxial deformations.

The growth of hydroxyapatite (HAp) surface layers that are different from bulk layers have been studied. Surface layers are the result of HAp having a variable composition from Ca10(PO4)6(OH)2 to approximately Ca9HPO4(PO4)5OH. These compositions exist over Ca/P ratio from 1.67 for stoichiometric to approximately 1.5 for fully calcium-deficient HAp. The variation in the composition is that only one HAp composition dissolves congruently. Surface layers are formed when the HAp has Ca/P ratios different from the congruently dissolving compositions.

The selective overgrowth approach was employed to grow bulk-like GaN layers by sublimation technique. To determined the lateral growth mechanisms in sublimation, the microstructure of selectively regrown GaN was investigated by cathodoluminescence, scanning electron microscopy and transmission electron microscopy. The effect owing to the reduction of dislocation density with different mask materials as well as the extension of the threading dislocation in the region of laterally regrown GaN are also analyzed.

Curvature measurements were performed to investigate the stress condition of AIN/Al2O3 heteroepitaxial structures. The structures were determined to be concave at the deposition temperature. However, the structures may become convex or remain concave on cooling to room temperature based on film thickness. The top layer of the film may be unstressed and cooling from the deposition temperature causes elastic strains of opposite sign. Further, an interplay between a variety of contributions establishes the magnitude as well as sign of structure curvature.

The temperature and the power dependence of the luminescence that resulted from the dislocations near the interface in the underlying silicon substrate side were analyzed using very thin and partially strained Si0.6Ge0.4/Si heterostructure. Dissociative energies were determined and compared to the literature values. Further, the absence of SiGe D lines was associated with the combined effects of the small conduction band offset and the large capture probability of the carriers by the dislocations in the main Si substrate.

A nitrogen radio frequency-plasma source was used to analyze the photoluminescence (PL) behavior of nitrogen-doped ZnSe epilayers grown by molecular beam epitaxy. A thermalization technique is presented to explain the bound exciton which involved in the capture and emission between the neutral donor bound exciton, the neutral acceptor bound exciton and the free exciton. The results show that there is consistency betwen quantitative analysis with the suggested method and the experimental data.

In recent years, the finite-difference time-domain (FDTD) method has found numerous applications in the field of computational electromagnetics. One of the strengths of the method is the fact that no elaborate grid generation specifying the content of the problem is necessary - the medium is specified by assigning parameters to the regularly spaced cubes. However, this can be a weakness, especially when the interfaces between neighboring media are curved or 'sloped' and do not exactly fit the cubic lattice. Since the E- and H-fields are only calculated at the regular intervals, sharp field discontinuities at the interfaces are often missed. Furthermore, the averaging of the material properties often leads to significant errors. In this paper, a post.processing method is presented, which approximates the correct field behavior at the interfaces by interpolating between the FDTD calculated values, splitting them into the components normal and tangential to the interfaces, and then enforcing the interface conditions for each of these components separately. Index Terms - Averaging of material properties, biological media, curved and 'sloped' interfaces, FDTD method, flux-related fields, interface conditions, layered spheres, linear interpolations, Mie series solutions.

An element template methodology is presented to solve composite plate problems using a serendipity hierarchical finite element implementation of Reddy's three-dimensional layerwise theory (1987). This methodology reduces the computational requirements associated with layerwise modeling, provided the plate structure can be represented in terms of only a few unique elements or templates. A diagonally preconditioned conjugate gradient algorithm is used in the template methodology for the solution of the finite element algebraic equations. The developed strategy does not require the formulation of a global stiffness matrix, it only requires the computation and recursive use of the element templates. Sample problems are investigated to prove the validity of the model.

Microstructures of enargite and luzonite ([Cu.sub.3]As[S.sub.4]) were studied using high-resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED). Enargite and luzonite are intergrown at the atomic level in samples from Recsk, Hungary. Both minerals typically contain faults along the planes of their close-packed layers. Comparisons of electron micrographs and images simulated for several types of fault models indicate that the planar defects can be interpreted as stacking faults in the regular cubic (luzonite) or hexagonal (enargite) sequence of close-packed layers. In addition to disordered layer sequences, two long-period, rhombohedral polytypes - 9R, [(21).sub.3] and 24R, [(311111).sub.3] - occur in enargite. The presence of defect-free luzonite and enargite indicates that both minerals grew directly from the hydrothermal solution. The disordered structures represent transitional structural states between luzonite and enargite and probably reflect the effects of fluctuating conditions during hydrothermal deposition.

X-ray diffraction and infrared, Raman and nuclear magnetic resonance spectroscopic studies, as well as thermal gravimetric analysis were done to characterize the formation of a new class of layered, microcrystalline polymers from the hydrolysis of n-octadecyltrichlorosilane. The results revealed that the polymeric condensate is composed of periodic layers, each bearing a monomolecular layer of intercalated water, separated by crystalline assemblies of alkyl chains.

Many crystalline solids have multiple nonequivalent sites among which different atoms show substitutional long-range order-disorder phenomena. The order-disorder kinetics of an atom among any n nonequivalent sites in a crystal can be described by the equation [x.sub.i] = [c.sub.i1] + [summation of] [c.sub.ij](t)[e.sup.[[Lambda].sub.j]t] where j=2 to n where [x.sub.i] is the site occupancy of the atom at site [s.sub.i], n is the number of nonequivalent sites, [[Lambda].sub.j] ([[Lambda].sub.1] = 0) is constant at a given temperature, pressure, and total composition of the crystal, and [c.sub.ij](t) is constant or polynomial in t. Four theorems governing a multi-site order-disorder process have been proved, requiring that [[Lambda].sub.j] must be either zero (only [[Lambda].sub.1] = 0), a negative real number, or a complex-valued quantity with the real part being a nonpositive number. The kinetic model becomes constrained and naturally complies with crystal-chemical conditions when the mole number per formula unit is chosen as the unit of all site-occupancy variables, or site multiplicities are explicitly incorporated into the model. When the mole fraction is directly used as the unit, the model becomes unconstrained, but it is a valid treatment that is as equally applicable to the multi-site order-disorder kinetics as the constrained model.

A novel electrostatic discharge (ESD) protection transistor with a buried SiGe narrow-bandgap layer favors current flows in the buried region. The induced current attenuates local overheating at the silicon surface. For the Machine Model with 300 volt level and the new structure, the peak lattice temperature is 400 degree celsius. The ESD protection device has high bipolar current gain and fast parasitic bipolar turn-on.

The two oxovanadium-organodiphosphonate phases H2N(C2H4)(2NH2)VO 2(O3PCH2CH2CH2PO3H)2 (1) and (VO)(H2O)(O3PCH2NH)(C2H4)(2NHCH2PO3) (2) are synthesized. The structure of (1) possesses phosphorous tetrahedra interconnected by the diphosphonate organic backbone into a stair-step structural motif and ribbons of corner-sharing vanadium square pyramids. In 2 the inorganic V/P/O layers are linked through the organodiphosphonate backbone in alternating inorganic and organic layers.

Analysis of melting and transient heating of thin polysilicon layers treated with pulsed excimer laser by using combined optical and electrical methods reveals that phase boundary propagation is not influenced by superheating. Numerical computations are performed through a phase-change model. The interface tracking and phase-change models are discussed.

Many new matrix techniques are being used in modeling ultrasonics waves in multilayered media. The techniques are affectively used in seismological studies and also to develop instruments to predict the response and modal properties of plates. Derivations of the equations of two matrix methods, Transfer Matrix and Global Matrix, are given in detail. Latest developments in different techniques and their use in ultrasonics are discussed.

A study of interface microstructure and strain relaxation of CdSe shows that the varying misorientations present along the interface of CdSe epilayer are associated with the proportion of different 60 degree misfit dislocations and stacking faults. The high density of the long stacking faults is due to dimorphic activity of CdSe. CdSe was atomic-epitaxy-grown on ZnSe/GaAs(001) and viewed using transmission and high resolution electron microscopy.

Examination of the local order in the layered materials H2MoO3, Li4Mo3O8, LiMoO2 and Li2MoO3 by molybdenum K-edge EXAFS studies reveals the presence of Mo3 metal-metal bonded triangles in Li2MoO3, H2MoO3 and Li4Mo3O8. EXAFS studies suggest that metal-metal bonding in LiMoO2 is more complex than that predicted by diffraction studies. Mo-Mo-bonded chains are present in LiMoO2, and a model is suggested for disordered chains existing in the MoO2 sheets.

Analysis of the development of aluminum-silicon (Al-Si) alloy titanium nitride (TiN) layered structures and their electromagnetic (EM) performance reveals that a large negative substrate bias causes structural transition in the TiN and that film deposition on an orientation controlled barrier TiN film enables the control of the crystallographic orientation of the alloy structures. Al-Si alloy films having a dominant (111) orientation show longer electromagnetic (EM) lifetime while those with (111) orientation have good EM resistance. Thus, enhancement of preferred orientation of Al-Si alloy films enables them to function as reliable interconnects.

A linear approximation model that depends on a probability distribution function and two functions representing the mechanical response of tissue and an equilibrium bubble helps represent the steady-state response evoked by a harmonically driven ultrasonic wave propagating through a bubbly liquid in tissues. Numerical data reveal the spatial velocity and pressure distributions in the fluid and tissue and the occurrence of spatial attenuation in the fluid.

Conventional methods help prepare large organic ionic crystals of 4-nitrophenol sodium salt dihydrate (NPNa) and DNPNa with deuterated water. X-ray diffraction study helps determine the structures of NPNa and DNPNa. NPNa has higher Vickers hardness and thermal conductivities than conventional organic molecular crystals. Spectrophotometric studies show that substitution of D2O for H2O in the NPNa crystal reduces the optical loss coefficient.

Window glass is principally produced by the float technique that causes the diffusion of tin into glass, creating a layer on each face. These have a refractive index ([N.sub.F]) that is slightly different from that found in the bulk of the glass ([N.sub.S]) and asymptotically approach this value. The Maxwell theory allows one to calculate the reflectance of the system (layer plus glass substrate) considering only the first order in the perturbation [Delta]N ([N.sub.F] = [N.sub.S] + [Delta]N). The depth profile of the complex refractive index of each layer may be determined with the assistance of multiangle ellipsometric measurements and the reflectance expression.

Transmission electron microscopy and energy dispersive x-ray spectroscopy to examine the micro-structure and composition of a YBa2Cu3O7(Y2O3) structure and composition of a trilayer film deposited on MgO reveal the occurrence of secondary phases in the top YBa2Cu3O7-x layer due to the presence of an yttria layer. The top layer containing barium copper oxide, covered by crystalline yttria particles that disturb the local microstructure and cause partial decomposition of YBa2Cu3O7-x due to resputtering, changes local deposition conditions. The decomposition of YBa2Cu3O7-x may also be due to a rise in oxygen pressure near the growing film due to yttria layer sputtering by plasma gas atoms and sputtered target atoms.

Study of 30-crown-10 (30C10) using NMR spectroscopy and X-ray crystallography reveals that four water molecules are bound to each other and the respective crown ether but not to components of neighboring units. When stacked in the crystal lattice crown, ether molecules form channels occupied by water molecules. This is the first investigation of an aliphatic crown ether larger than 18-crown-6 and lacking guest species.

A sacrificial layer of Al increases its retention capacity when high doses of 5 MeV Pt ions are implanted into Ni. When Al thickness of 3600 angstroms is used with a dose of 7 times 10 to the power of 17 Pt/cm squared, the optimum concentration is approximately 19 at. percent Pt in Ni. The saturation concentration is approximately 10 at. % Pt in the absence of a sacrificial layer.

A model of imperfect interfacial contact was used to determine the mechanical properties of very thin adhesive layers during its stage of cure. The model was able to describe quantitatively the changes occurring in the reflection coefficient of an ultrasonic wave as the structure of the layer changes. These findings validate the use of the method in studying very thin adhesive bonds and thin film effects such as heterogeneous growth and anisotropy.

Transmission electron microscopy and x-ray diffraction analyses are employed in the study of the cobalt disilicide (CoSi2) structures formed via the vapor-deposition of cobalt films on silicon(100) substrates. CoSi2 layers were formed at the silicon-cobalt silicide (Si/CoSi) boundary after the substrate was annealed at 500 degrees centigradee. Different growth orientations of the CoSi and CoSi2 layers were then observed, hinting the lack of epitaxial relationship between these two layers. A number of orientations were also observed for the grains of the CoSi2 layers. Results of grain orientation analyses and lattice-matching calculations are given.

The article discusses the problems of boundary frictionless thermoelastic contact for a layer. Equations to formulate contact problems are derived.

Structure and magnetoresistance analyses of annealed sputtered (Ni81Fe19, Ni66Fe16Co18)/Ag granular multilayers reveal that the annealing temperature and the magnetic layer thickness, which control the mean magnetic particle size, influence the magnetoresistance (MR), thermal stability and the magnetoresistive sensitivities of the granules. Over 30% MR occurs at 4.2 K for an initial magnetic thickness of 4 angstroms. The magnetic thermal stability and consequently, the magnetoresistive sensitivities, are enhanced by increasing the thickness to 20 angstroms.

Analysis of a modular-approach-based design and crystal structure of an organic solid with wide channels reveals that planar, rigid macrocyclic building blocks aid the development of these channels. The macrocycles contain phenolic groups on their outer rims. These groups form hexagonally close-packed, two-dimensional hydrogen-bonded networks. The layers are arranged to maintain registry between the macrocyclic cavities, leading to extended channels of the solid, which are filled with solvent molecules.

A study of the theoretical feasibility of constructing a tailored, layered sheet reveals that it lowers the stress concentrations caused by a circular hole in a field of balanced biaxial tension without necessarily lowering the average circumferential stress at the boundary of the hole. A 'neutral' hole would result in cases where the stress concentration is totally abolished.

Layered structures of well-aligned carbon nanotubes were grown using three variations of vapor-phase chemical vapor deposition growth processes. Layers were grown with thicknesses ranging from several microns to several hundred microns, and structures were grown with well over 100 layers.

An investigation on the Sm-Co/Co hard/ soft multilayers is presented with varying thickness of soft phase layers. The result suggested that the 1min annealing at 525 degree Celsius retains the layer structure unchanged and the hard phase of Sm-Co forms.