Silica composites containing nanometer dimension colloids have been fabricated by implantation of Ag ions followed by Sb ions, and by implantation of Sb ions followed by Ag ions. Doses for the sequential element implantations were in ratios of 9 : 3 Ag : Sb and 3 : 9 Sb : Ag with the total dose held constant at 12 × 1016 ions/cm2. Energies of implantation were 305 keV for the Ag ions and 320 keV for the Sb ions. Single element colloids were also fabricated by implantation of Ag or Sb using the same nominal dose and implantation energy of the sequential implantations. Approximately spherical particles were formed in all implanted samples. Microstructures of the nanoclusters in the various samples were markedly different. Selected area diffraction techniques revealed that alloyed phases of Ag–Sb were formed in some of the sequential implantations. The microstructure and the optical response of the nanocluster glass composites were found to be strongly dependent upon the order of the ion species implanted. The optical spectra of the 3 : 9 Sb : Ag sample displays two resonance peaks indicative of a Ag resonance peak and a resonance peak of an alloyed phase of Ag–Sb. Optical spectra for the 9 : 3 Ag : Sb sample displays two broad absorption peaks indicative of coated particles.

Composite powders of molybdenum silicide–SiC were synthesized by reacting mixtures of (Mo–SiO2 –C), (Mo–Si3N4 –C), and (Mo–SiO2 –Si3N4 –C) powders at 1300 °C. In the (Mo–SiO2 –C) system Mo5Si3 and Mo3Si formed predominantly. MoSi2 formed the major constituent of the reaction product from powder mixtures containing Si3N4. Vapor-solid SiC whiskers formed in the (Mo–SiO2 –C) system. Vapor-liquid-solid whiskers of SiC and Mo5Si3C formed in (Mo–SiO2 –Si3N4–C) and (Mo–Si3N4 –C) systems, respectively. The mechanism of formation of the VLS whiskers and molybdenum silicides was identified as follows: initially a thin layer of Mo2C forms on Mo particle; the Si vapor from thermal decomposition of Si3N4 deposits on the Mo2C surface and forms a droplet of ternary “Nowotny phase” Mo<5Si3C<1; an SiC/Mo5Si3C whisker forms by nucleation and growth from the supersaturated ternary phase; after reaction with the Mo2C layer, the SiO/Si vapor further reacts with Mo particle to form bulk silicides.

New and modified mechanisms are proposed to account for detailed observations of carbon encapsulation of Fe, Ni, and Co nanocrystals. The mechanisms are based on aerosol and gas phase chemistry and on the catalytic effects of transition metals. Two parameters are found to qualitatively dominate production: the local-path carbon-to-metal ratio (LCM) and the global carbon-to-metal ratio (GCM). LCM's select which mechanisms are active along each pathway within the reactor. The GCM places bounds upon and determines the weighting between different LCM's and thus determines the distribution of different nanoscale products within the collected, macroscopic product. A two part processing parameter → mechanism → product map links the components. The generality of the model is discussed throughout with reference to related processes and the encapsulation of other materials.

Continuous microindentation has been carried out on an iron–3% silicon single crystal in 1 M sulfuric acid. The ability of the material to support elastic loading is directly linked to the presence of thermally grown oxide films and passive films applied through potentiostatic control of the sample. When the passive film is removed, either by chemical or electrochemical means, the iron alloy can no longer sustain pressures on the order of the theoretical shear strength of iron. Instead, the metal behaves in a traditional elastic-plastic manner when no film is present. The oxide film at the edges of the indentation can sustain applied tensile stresses up to 1.2 GPa prior to failure. Indentation in materials undergoing dissolution must account for the rate of material removal over the remote surface and the resulting plastic deformation around the contact of the indentation.

The ion-assisted nucleation of diamond was studied in a microwave plasma chemical vapor deposition system to gain insights into the processes controlling this phenomenon. The dependence of the nucleation density on bias voltage and temperature, as well as experiments with an electrically isolated substrate, are consistent with an ion bombardment mechanism for diamond nucleation. However, the growth of these nuclei is dominated by neutral species rather than ions. Measurements of the bias current under various conditions also provide details on the roles of the incident ion flux and substrate electron emission during this process. Furthermore, Monte Carlo simulations of the ion energy distribution at the substrate are compared to experimental measurements. Preferential sputtering, thermal spike, and carbon subplantation nucleation mechanisms are assessed based on the experimental and modeling results.

Sputtered TiN (30–120 nm thick)/Ti (30 nm thick) films were studied as a diffusion barrier between silicon substrate and copper films. The effects of TiN thickness and the existence of a SiO2 layer between Ti and silicon substrate on the diffusion barrier property were investigated using various characterization methods. The copper diffusion barrier property of TiN/Ti was found to be affected not only by the TiN thickness, that is diffusion distance, but also by the microstructure of the TiN, which changes with the thickness of TiN film. The existence of the SiO2 layer enhanced the diffusion barrier property of TiN/Ti. This is because the SiO2 layer between Ti and Si inhibited the formation of titanium silicides, so the Ti layer was available to be used as the sacrificial diffusion barrier for copper.

Diamond was deposited on smooth Si3N4-coated Si substrates using hot-filament chemical vapor deposition (CVD). Prior to diamond deposition, the substrates were pretreated under high temperature (700–900 °C) by decomposed pure hydrogen. The experimental results show that these pregrowth processes at a substrate temperature of 850 °C enhanced the diamond nucleation on Si3N4. This indicated that decomposed hydrogen acted on the substrate to produce active centers (<100 nm), which promoted diamond nucleation. It has also been suggested that Si3N4 coating can inhibit carbon transport into the substrate, and it is beneficial to the diamond nucleation.

Carbon nitride thin films have been successfully deposited by ablating a graphite target (99.999%) in nitrogen gas ambient using the second (532 nm) or third (355 nm) harmonic of a Q-switched Nd : YAG laser. Carbon nitride films consisting of approximately 40% nitrogen were obtained at 7.5 × 10−3 Pa of nitrogen gas pressure using the third harmonic laser. The C–N chemical bond in the films was observed by x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Ellipsometric studies revealed that the refractive index of the fabricated films decreased with increasing nitrogen concentration.

The diffusion of magnesium into lithium niobate single crystal under different diffusion conditions has been studied by x-ray diffraction, glancing-incidence x-ray diffraction, differential thermal analysis, and scanning electron microscopy in an attempt to determine the diffusion mechanism and evaluate the crystallinity of the diffused layer. It is found that the magnesium diffused layer exhibits the crystal structure of an unknown compound from the Mg–Li–Nb–O ternary system and MgNb2O6. The MgNb2O6 is in the surface layer of the magnesium diffused layer, while the unknown compound is in the subsurface layer beneath the MgNb2O6. It is proposed that this unknown compound and MgNb2O6 which form during a solid state reaction between a thin layer of MgO and a lithium niobate crystal in a Li2O-rich atmosphere are the real sources for Mg ion indiffusion into lithium niobate crystal. The changes in Curie temperature with diffusion parameters are noted. Reasons of lattice distortion and mechanisms of Mg ion indiffusion are discussed and analyzed.

We demonstrate the effect of particle size and quantum confinement on the luminescence properties of nanoscale silicon thin films. Thin films of agglomerated silicon nanoparticles are synthesized using pulsed laser ablation supersonic expansion. Following deposition, standard semiconductor processing techniques are employed to reduce the nanoparticle size. Films are oxidized both in air and chemically to reduce the silicon core dimensions, resulting in a shift of the luminescence emission peak to shorter wavelengths. Removal of the oxide using hydrofluoric acid (HF) results in further blueshifting of the luminescence, as does subsequent reoxidation in air and using nitric acid. The luminescence properties of samples are also studied as a function of excitation intensity. For room temperature excitation with a pulsed 355 nm source, a saturation of the photoluminescence intensity at high excitation intensity is observed, along with a blueshift of the peak PL wavelength. This behavior is found to persist at reduced temperature. A saturation of PL intensity, but no blueshift, is observed for high excitation intensity using a cw 488 nm source at room temperature. At reduced temperatures, no saturation of emission intensity occurs for high intensity 488 nm cw excitation. Both the irreversible shifting of the peak PL wavelength with size reducing treatments and the PL behavior at high excitation intensities indicate that quantum confinement determines the luminescence wavelength.

New electrolytic systems were prepared by reacting K3Fe(CN)6 and K2PdCl4 in a mixture of water and poly(ethylene glycol) 600 (PEG). The reaction occurs in two steps: first a gel is formed, which then shrinks, releasing the solvent. The product thus obtained has the consistency of a smooth, solid plastic paste and is very stable. The influence of the reaction mixture on the structure, morphology, and conductivity of the products was investigated carrying out three preparations (I, II, III) at increasing ratio PEG 600/H2O. By FT-IR studies and analytical data it was concluded that these materials are inorganic-organic networks containing CN bridges between Fe and Pd atoms and PEG 600 bridges between Pd atoms. Scanning electron microscopy studies revealed that the morphology of polymers I, II, and III is significantly influenced by the conditions of the synthesis. Conductivity measurements made at different temperatures showed that polymers I, II, and III conduct ionically. The conductivity of polymer I, which was synthesized with the highest water/PEG 600 ratio, is on the order of 1.4 · 10−3 Sycm at 25 °C.