Crystalline thin films of silicon nitride have been grown on a variety of substrates by microwave plasma-enhanced chemical vapor deposition using N2, O2, and CH4 gases at a temperature of 800 °C. X-ray diffraction and Rutherford backscattering measurements indicate the deposits are stoichiometric silicon nitride with varying amounts of the α and β phases. Scanning electron microscopy imaging indicates β-Si3N4 possesses sixfold symmetry with particle sizes in the submicron range. In one experiment, the silicon necessary for growth comes from the single crystal silicon substrate due to etching/sputtering by the nitrogen plasma. The dependence of the grain size on the methane concentration is investigated. In another experiment, an organo-silicon source, methoxytrimethylsilane, is used to grow silicon nitride with controlled introduction of the silicon necessary for growth. Thin crystalline films are deposited at rates of 0.1 μm/h as determined by profilometry. A growth mechanism for both cases is proposed.

The chemical stability of TiB2 and TiN in a silicon nitride matrix under various conditions of temperature and gaseous environments was investigated. The addition of TiB2 and TiN on the microstructure and mechanical properties was also studied. No trace of interactions between TiN and Si3N4 was noticed. The addition of TiB2 to Si3N4 enhanced conversion of the α to β phase of the Si3N4 matrix. Observations of BN and TiN indicated a possible reaction between TiB2 and Si3N4. The fracture toughness of Si3N4 was substantially enhanced with the addition of TiB2 or TiN, while the strength was decreased. Crack deflection was the major toughening mechanism in a Si3N4/TiB2 composite. Most of the microcracks passed through TiN particles and cleavaged along preferred orientations with large deflection angles.

Low energy bombardment of CHn+ at 100-800 eV has been used to prepare TiC film at room temperature by dual ion beam sputtering. The ion bombardment energies and densities obviously affect the metallographic morphology, the crystalline orientation, and constituent ratio of TiC films. TiC films formed under 200-600 eV CHn+ bombarding with 120-190 μA/cm2 possess much finer and compact microstructure in the compressive stress state. Its hardness is in the range of 2650-2880 kgf/mm2. The tribological tests indicate that TiC films synthesized on AISI 52100 steel by DIBS with low energy bombardment exhibit low friction coefficient and good wear resistance.

The phase chemistry and thermodynamics of the Ti-Si-N system are reviewed leading to a revision of the ternary phase diagram at 1273 K to include the extended compositional ranges of δ-TiNx and Ti5Si3(Ny) and the compounds Ti3Si, Ti5Si4, and α-Ti. This same information is presented in the form of phase stability diagrams which plot the stability criteria for each phase as a function of thermodynamic activity of one component and the relative composition of the other two components. Plots in terms of log asi vs Ti/(Ti + N), log aN2 vs Si/(Ti + Si), and log aTi vs N/(Si + N) were constructed. All diagrams are consistent with current knowledge of phase compatibility and, therefore, are topologically correct. Further refinement will be possible as more accurate information on thermodynamics and compositional limits of solid solutions becomes available.

The microstructures of GaN films, grown on (001) and (111) Si substrates by a two-step method using Electron Cyclotron Resonance assisted-Molecular Beam Epitaxy (ECR-MBE), were studied by electron microscopy techniques. Films grown on (001) Si had a predominantly zinc-blende structure. The GaN buffer layer, grown in the first deposition step, accommodated the 17% lattice mismatch between the film and substrate by a combination of misoriented domains and misfit dislocations. Beyond the buffer layer, the film consisted of highly oriented domains separated by inversion domain boundaries, with a substantial decrease in the defect density away from the interface. The majority of defects in the film were stacking faults, microtwins, and localized regions having the wurtzite structure. The structure of the GaN films grown on (111) Si was found to be primarily wurtzite, with a substantial fraction of twinned zinc-blende phase. Occasional wurtzite grains, misoriented by a 30°twist along the [0001] axis, were also observed. A substantial diffusion of Si was seen in films grown on both substrates.

The growth behavior of Pb2+-containing ferroelectric thin films has been systematically examined. The kinetics of the formation of perovskite phase were successfully enhanced by using a material containing no Zr4+-ions, viz., Pb0.95La0.05Ti0.9875O3 (PLT) films, and by utilizing platinum coating on silicon substrate. Meanwhile, the formation of TiO2 phase (rutile) on PLT/Pt(Si) films has been observed and was ascribed to both the outward diffusion of Ti4+-ions from the Ti-layer underneath the Pt-coating and the loss of Pb2+-ions on the surface of the films. The perovskite materials, which were free of either pyrochlore, Zr-rich phase, or TiO2 phase, can be obtained by in situ depositing the PLT films at 450 °C substrate temperature and 1 mbar oxygen pressure. Thus obtained thin films possessed high dielectric constant, ∊r = 1346 and tan δ = 0.071 at 10 kHz, and large charge storage density, Qc = 5.4 μC/cm2 at 50 kV/cm.

The flocculation of an unstabilized suspension of fine ceramic particles is advanced as the explanation for the formation of cracks in a “liquid” suspension. The development of cracks was observed several minutes after reheating wax-based ceramic moldings above the melting point of the wax and was accompanied by phase separation of the wax from the molding. Calculations of the acceleration of particles under London dispersion forces in a viscous fluid show the “time to impact” as a function of initial separation distance, fluid viscosity, and particle size. This is compared with the intercollision time calculated from classical flocculation theory, and it is shown that for crowded suspensions initial interparticle distances are such that the London force field cannot be neglected. Methods of preventing the flocculation are described.

Ca0.5Sr0.5Zr4P6O24 (CSZP) powders were prepared by the decomposition/combustion method using Ca(NO3)2 · 4H2O, Sr(NO3)2, ZrO(NO3)2 · xH2O, NH4H2PO4, urea, and NH4NO3 as starting materials. The homogenized slurries of the mixture were heated at 500 °C for 5 min to obtain CSZP powders. The as-synthesized powders were amorphous and crystallized after heating 800 °C for 2 h. The specific surface area of the powder was varied with the batch weight of starting materials or the amount of urea and ammonium nitrate. Powders with high specific surface area (150 m2/g) could be produced by this method. The sinterability of the powders was comparable to that of sol-gel derived powders. The sintered density of the compacts was 99% of theoretical after firing in air at 1350 °C for 6 h.

A procedure is described that yields uniform spherical colloidal palladium particles of modal diameters ranging between 0.1 and 0.7 μm. The process consists of two stages. First a monodispersed solid composite precursor is precipitated in solutions containing PdCl2, urea, and a nonionic surfactant. The resulting particles are then reduced in aqueous media, either by hydrazine or ascorbic acid in the presence of a protective agent. No change in particle shape occurred during the transformation to pure metals.

Epitaxial Grain Growth (EGG) is an orientation-selective process that can occur in polycrystalline thin films on single crystal substrates. EGG is driven by minimization of crystallographically anisotropic free energies. One common driving force for EGG is the reduction of the film/substrate interfacial energy. We have carried out experiments on polycrystalline Ag films on Ni(001) substrates. The orientation dependence of the Ag/Ni interfacial energy has been previously calculated using the embedded atom method. Under some conditions, EGG experiments lead to the (111) orientations calculated to be interface- and surface-energy-minimizing. However, when Ag films are deposited on Ni(001) at low temperature, EGG experiments consistently find that (111) oriented grains are consumed by grains with (001) orientations predicted to have much higher interface and surface energy. The large elastic anisotropy of Ag can account for this discrepancy. Strain energy minimization favors growth of (001) grains and can supersede minimization of interfacial energy if sufficient strain is present and if the film is initially unable to relieve the strain by plastic deformation.

We have investigated the effects of process parameters such as rf power, substrate, and gas pressure PAr on preferred orientation, microstructure, and magnetic properties of Ni-Zn-Cu ferrite thin films deposited by conventional rf magnetron sputtering. The texture structure was developed in the ferrite films deposited on the SiO2/Si(100) substrate at low rf power conditions. The ferrite film on the Si(111) substrate always had (111) texture irrespective of process parameters due to lattice matching, but the texture of the ferrite film on SiO2/Si(100) changed from (111) to (100) and finally returned to (111) orientation again with decreasing PAr. Such behavior would occur presumably due to the characteristic atomic stacking sequence corresponding to a given condition of the ion bombardment. The ferrite films deposited at low PAr had a denser microstructure consisting of tightly packed columnar grains with a smoother surface, better adhesion to the substrate, and better crystallinity than those at high PAr. Hc‖ of ferrite film deposited at low PAr was larger than that at high PAr and also larger than Hc⊥ of that deposited at the same PAr because larger compressive stress was induced at low PAr than at high PAr.

Ultrasonic propagation of longitudinal waves (CL mode) has been investigated as a function of temperature in a single crystal of a TaH0.51 hydride. Stepwise changes of the elastic constant CL and of the attenuation A have been observed in the vicinity of the β ↔ ∊ and ∊ ↔ α phase transitions. These changes occur over narrow temperature ranges corresponding to regions of coexistence of two phases. A relatively small temperature dependent softening is displayed by CL on approaching Tβ→∊ from the low temperature side. At the transition temperatures no divergency has been observed in the attenuation, which appears to originate from domain boundary motions, rather than from the transitions themselves. A determination of the H diffusion coefficient by a permeation method at high temperature supports a view that adiabatic tunneling is an effective mechanism even at temperatures as high as 1173 K.

Carbon films with up to 32 at. % of nitrogen have been prepared with ion beam assisted magnetron, using a N2+/N+ beam at energies between 50 and 300 eV. The composition and density of the films vary strongly with the deposition parameters. EELS, SXS, XPS, and IR studies show that these a-C: N films are mostly graphitic and have up to 20% sp3 bonding. Nitrogen is mostly combined with carbon in nitrile (C ≡ N) and imine (C=N) groups. It is shown by RBS and NDP that density goes through a maximum as the average damage energy per incoming ion increases. Positron annihilation spectroscopy shows that the void concentration in the films goes through a minimum with average damage energy. These results are consistent with a densification induced by the collisions at low average damage energy values and induced graphitization at higher damage energy values. These results are similar to what is observed for Ar ion assisted deposition of a-C films. The mechanical properties of these films have been studied with a nanoindenter, and it was found that the hardness and Young's modulus go through a maximum as the average damage energy is increased. The maximum of mechanical properties corresponds to the minimum in the void concentration in the film. Tribological studies of the a-C: N show that the friction coefficient obtained against diamond under dynamic loading decreases strongly as the nitrogen composition increases, this effect being more pronounced at low loads.

Electron diffraction intensities from cylindrical objects can be conveniently analyzed using Bessel functions. Analytic formulas and geometry of the diffraction patterns from cylindrical carbon nanotubes are presented in general forms in terms of structural parameters, such as the pitch angle and the radius of a tubule. As an example the Fraunhofer diffraction pattern from a graphitic tubule of structure [18,2] has been simulated to illustrate the characteristics of such diffraction patterns. The validity of the projection approximation is also discussed.