A new method for depositing parylene-F (PA-F) thin films on silicon substrates has been explored. Hydrogen has been used as a carrier gas along with liquid precursors, dibromotetrafluoro-p-xylene and 1,4-bis(trifluoromethyl)benzene, to deposit PA-F. The properties of this film have been compared with the films obtained by the Gorham dimer method and the liquid precursor method using FTIR, XPS, and XRD. The PA-F films deposited by the dimer or liquid precursor acquired some kind of microcrystallinity on annealing. However, the PA-F films deposited in the presence of hydrogen were amorphous on annealing. This property could be potentially exploited for application in microelectronic device fabrication.

Starting from elemental powders, simultaneous synthesis and compaction of SiC were conducted at 3 GPa pressure and temperatures in the range 2100–2900 K. The sintered compacts were characterized by x-ray diffraction, microhardness measurements, and microscopic studies. The efficiency of formation of SiC was dependent on the particle size of the silicon powder, crystallinity of the reactant carbon, molar ratio of silicon and carbon, and synthesis temperature and time. Carbon in excess of the stoichiometric amount was required to obtain compacts free from residual silicon. The SiC samples, with a Si: C molar ratio 1: 1.05, prepared at 2100 K for 300 s had a density and hardness of 3.21 g/cm3 (98.8% of theoretical density) and 22 GPa, respectively. The crystal structure of the SiC depended on the synthesis temperature. Pure β–SiC in the temperature range 2100–2500 K, and a mixture of α– and β–SiC above 2500 K were obtained. The β–SiC was highly crystalline and nearly defect-free.

Measurements of x-ray diffraction (XRD) profiles have been performed on commercially pure Fe and Al powders, cryomilled Fe–3 wt.% Al powders, cold pressed (CP) pure Fe and Al, hot pressed (HP) and hot isostatically pressed (HIP) Fe–3 wt.% Al. Scherrer equation (SE), integral breadth analysis (IBA), and single-line approximation (SLA) methods have been employed to extract grain size and microstrain. The results demonstrate that, in the case of the cryomilled nanocrystalline Fe–3 wt.% Al powders, all these XRD techniques yielded reasonable, consistent grain size results. However, discrepancies were found in cold pressed (CP-Fe), hot pressed (HP-Fe–3 wt.% Al), and hot isostatically pressed (HIP-Fe–3 wt.% Al) samples. TEM imaging revealed the presence of a certain density of dislocations inside the grains in the HP-Fe–3 wt.% Al and HIP-Fe–3 wt.% Al, which is thought to be partly or fully responsible for the observed discrepancies.

Based on the stability analysis of the closed pores in two dimensions which was determined mathematically with their particle coordination number and dihedral angle, the stability of those in three dimensions was determined with a spherical pore model. The model is set up by first excluding the effect of interface tension, so the pore was supposed to be spherical, and then the tensile stress arisen from the interface tension was supposed to act on this hypothesized spherical pore. On the basis of the spherical pore model, microstructure models based on pores, not grains, for the real powder compacts were first established. Densification kinetics were then determined from the models by the densification rate equations, which were derived by relating density to pore size to grain size ratio, for the intermediate and final stages of sintering. The criteria for pore shrinkage were discussed quantitatively. The derived equations can be used to simulate the relation between densification rate and density during heating with a constant rate and for the explanation of the effects of pore size distribution, agglomerates, and green density on sintering.

A variable-temperature (79, 145, and 293 K) extended x-ray absorption fine structure study, using rare-earth LIII absorption edges, is reported for phosphate glasses doped with rare-earth elements (R, where R = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Er) with compositions close to metaphosphate, R(PO3)3. The results yield nearest-neighbor R–O distances that demonstrate the lanthanide contraction in a glassy matrix and an R–O coordination intermediate between 6 and 7 for rare-earth ions with smaller atomic number (Z) and 6 for rare-earth ions with larger Z. Thermal parameters show no significant changes in R–O distances or coordination numbers between 293 and 79 K. There is evidence of an R–P correlation between 3.3 and 3.6 Å and the beginning of a second R–O correlation at approximately 4 Å. No R–R correlations up to a distance of approximately 4 Å were observed.

A fractional factorial design was implemented to optimize the experimental conditions for the preparation of ultrafine lanthanum-doped strontium titanate from titanyl acylate precursors. The effects of preparation conditions such as the molar ratio of acetic acid to titanium alkoxide, the water to titanium alkoxide ratio, pH value, the reaction temperature, and stirring speed were systematically studied by using Taguchi orthogonal array design. Results indicated that the effects of the reaction temperature and stirring speed on the reaction were the key variables influencing the average particle size of powders obtained. By combining the optimal settings of the two influential processing variables, it was possible to obtain an ultrafine powder with a particle size of about 340 Å. This was put to a test in the laboratory, and a polycrystalline, narrow size distribution ultrafine SrTiO3 powder that had a particle size of about 380 Å and readily sintered at 1150–1250 °C was obtained.

Amorphous ceramics with the chemical composition Si3B3N7 and SiBN3C were produced from single-source molecular precursors by polymerization and pyrolysis. The powder and fiber materials were investigated by means of energy filtering transmission electron microscopy. The intensity of elastically scattered electrons is recorded to calculate the pair distribution function of these ceramics. In the pair distribution function of Si3B3N7 three significant maxima at 0.144, 0.172, and 0.291 nm are clearly resolved and are assigned to the pair distances B–N, Si–N, and Si–Si (N–N), respectively, by comparison to crystalline materials. The predominant structural units of the ceramic are trigonal planar BN3 and tetrahedral SiN4 groups, which are close to their regular symmetry. The overall pair distribution function of SiBN3C is very similar to that of Si3B3N7; however, the maxima are broadened due to the incorporation of carbon into the network. High-resolution mapping of the elements Si, B, N, and C with electron spectroscopic imaging reveals a homogeneous distribution on a subnanometer scale without precipitation or separation of, for example, carbon-rich clusters. Similarly, elemental mapping of Si3B3N7 reveals a random distribution of the elements Si, B, and N at the same scale. Both new ceramics consist of an amorphous network with bonds and coordinations as preformed in the precursor.

The indentation load P versus depth h curves are examined to investigate the time-dependent surface deformation of viscoelastic materials. The viscoelastic P–h curves significantly depend on the temperature of measurement and the penetration rate of indentation. Sneddon's elastic solution of a conical indentation is extended to a viscoelastic one for a conical or a pyramidal indentation in terms of the hereditary integral. Several types of viscoelastic problems are discussed in relation to the test techniques and analyses for determining the relaxation modulus E(t) and the creep compliance D(t). The superposition rules of time–temperature, penetration depth–temperature, and penetration depth–penetration rate are examined. The viscoelastic indentation tests (constant rate penetration test and constant load creep test) of amorphous Se are conducted at temperatures from 10 to 42 °C. The theoretical considerations and the test results encourage pyramidal indentation as an efficient microprobe for the viscoelastic characterization, in particular, of extremely small-size test specimens and ceramic, metal, and polymer thin films coated on substrate.

KTiOPO4 (KTP) phase formation in stoichiometric mixtures corresponding to chemical formulas of {A1} [B5+1/2C3+1/2]O(D5+)O4 (A = K+; B = Nb5+ and Ta5+; C = Al3+, Cr3+, Ga3+, Fe3+, and In3+; and D + P5+ and As5+), and {A+} [B5+2/3C2+1/3]O(D5+)O4 (C = Mg2+ and Zn2+) prepared by solid-state reaction technique is reported. It was found that the mixtures containing Nb5+, Ga3+, Fe3+, and As5+ form the longest series of members of the KTP structural family. KTP phase formation was detected by x-ray powder diffraction analysis. Comparison of the lattice parameters measured with those known for the nonsubstituted crystals of the KTP family was carried out. The data obtained were used for the discussion of variations of KTP structural stability on composition.

Dense, uniform, and adherent chemically vapor-deposited mullite coatings were deposited on SiC substrates using the AlCl3–SiCl4–H2–CO2 system. Typical coating morphology consisted of a thin interfacial layer of γ–Al2O3 nanocrystallites embedded within a vitreous SiO2-based matrix. When a critical Al/Si ratio of 3.2 ± 0.29 was reached within this nanocrystalline layer, mullite crystals nucleated and grew as columnar grains. The thickness of the nanocrystalline layer decreased as the input AlCl3/SiCl4 ratio was increased. In all cases, the Al/Si composition in the coating increased from the coating/substrate interface to the coating surface. Critical factors leading to the nucleation and growth of mullite crystals are discussed in this article.

(Pb,La)(Zr,Ti)O3 (PLZT) films with thicknesses of 150 and 225 nm were prepared by the chemical solution deposition method on sputtered Pt/IrO2 coated on SiO2/Si wafers. The annealed films revealed two different microstructures: fined-grained and large-grained. The thinner film had the largest grain size and highest leakage current, whereas the thicker film had small grains and lower leakage. Atomic force microscope images showed that the thinner film had half-domed-shaped grains, which were about one-third thinner at the grain boundary triple points. These triple points also contained a nanocrystalline nonstoichiometric secondary phase, which contributed to high leakage. A model was developed showing differences in crystallization on the basis of grain growth and number of nuclei on the Pt surface. These results indicate the importance of controlling the film microstructure and its relationship to the film electrical properties.

Rapid thermal processing of BaTiO3 and TiO2 pressed powders at 500 °C/min to 1250 °C for 2 h in an infrared furnace resulted in a mixture of Ba2Ti9O20, BaTi4O9, and TiO2. Further heat treatment at 1390 °C led to 96 vol% phase-pure Ba2Ti9O20 from an initial mixture devoid of any dopant. Heat treatment at rates decreasing to 5 °C/min facilitated agglomeration of TiO2. This, in turn, increased the diffusion distance required for reaction of BaTi4O9 and TiO2 to form Ba2Ti9O20.

A polymerized organic–inorganic complexion route is introduced for the synthesis of yttrium aluminum garnet, YAG (Y3Al5O12) and cordierite (Mg2Al4Si5O18) powders. Long-chain polymers such as polyvinyl alcohol (–[CH2–CHOH]-n or PVA) or polyethylene glycol (H[O–CH2–CH2]nOH or PEG) were used as the organic carriers for a precursor ceramic gel. Calcined powders were very porous and homogeneous in distribution of components. Experimental studies by differential thermal analysis and thermogravimetric analysis, x-ray diffraction, solid-state nuclear magnetic resonance, and Fourier transform infrared spectrometry indicated that metal-ion chelation is not the primary mechanism for obtaining molecularly homogeneous precursor powders. Water-soluble cations of mixed oxides in the PVA or PEG process were sterically entrapped in the entangled network and resulted in fine and pure, mixed oxide powders.

A disappearing sintering aid was used to promote densification during the initial and middle stages of sintering and to be removed in gaseous form from the specimens during the final stage of sintering. From thermodynamic consideration such as assessment of Gibbs free energy change of formation of Al2O3 compounds including metal-oxide and evaluation of the vapor pressure of metal-oxide, Li2O is expected to become a disappearing sintering aid for AlN sintering. Doping with Li2O resulted in densification of AlN ceramics with Y2O3 and CaO additives by sintering at a firing temperature of 1600 °C. The amount of Li2O in the specimens decreased by volatilization at temperatures higher than 1300 °C, and its amount was at a level of several ppm after firing at 1600 °C for 6 h. Low-temperature densification of AlN specimens by addition of Li2O also caused the improvement of thermal conductivity and mechanical strength of sintered specimens. Present results indicate that a Li2O addition is effective for AlN sintering. Furthermore, LiYO2 was also used as a new sintering aid instead of Li2O and Y2O3, and the results of thermal conductivity and mechanical strength are shown.

Cobalt disilicide contacts to silicon–germanium alloys were formed by direct deposition of pure cobalt metal onto silicon–germanium films on Si(001) substrates. Segregation of germanium was observed during the reaction of the cobalt with the silicon–germanium alloy. The nature of the Ge segregation was studied by transmission electron microscopy, energy dispersive spectroscopy, and x-ray diffraction. In the case of cobalt films deposited onto strained silicon–germanium films, the Ge segregation was discovered to be in the form of Ge-enriched Si1−xGex regions found at the surface of the film surrounding CoSi and CoSi2 grains. In the case of cobalt films deposited onto relaxed silicon–germanium films, the Ge segregation was dependent on formation of CoSi2. In samples annealed below 800 °C, where CoSi was the dominant silicide phase, the Ge segregation was similar in form to the strained Si1−xGex case. In samples annealed above 800 °C, where CoSi2 was the dominant silicide phase, the Ge segregation was also in the form of tetrahedron-shaped, Ge-enriched, silicon–germanium precipitates, which formed at the substrate/silicon– germanium film interface and grew into the Si substrate. A possible mechanism for the formation of these precipitates is presented based on vacancy generation during the silicidation reaction coupled with an increased driving force for Ge diffusion due to silicon depletion in the alloy layer.

Silicon nitride was fabricated by adding Y2O3 and Nd2O3 as sintering additives, sintering for 8 h at 1900 °C, and heat treating for 4 h at 2200 °C to enhance grain growth. The microstructure was investigated by scanning electron microscopy, high-resolution electron microscopy, energy dispersive x-ray spectroscopy (EDS), and electron microdiffraction. This material had a duplex microstructure composed of many fine grains and a few coarse grains. In β–Si3N4 grains, second-phase particles with the composition of liquid phase, Y–Nd–Si–O or Y–Nd–Si–O–N, in the size of 10–30 nm were observed. EDS spectra and microdiffraction patterns revealed that those were amorphous or crystalline particles of Y–Nd–apatite, (Y,Nd)10Si6O24N2. These particles were presumably formed during cooling by the precipitation of Y–Nd–Si–O–N, which was trapped in the β–Si3N4 grains as solid solution or trapped liquid. The results suggest that attention should be paid to the trace amounts of trapped elements in β–Si3N4 grains in trying to improve the thermal conductivity of sintered silicon nitride.

Bulk thermal expansion properties of 19 members of the A2M3O12 family of tungstates and molybdates were determined from room temperature to 800 °C. The observed behavior ranges from strong negative thermal expansion (α = −11 × 10−6 K−1) in Sc2W3O12 to near zero thermal expansion in Al1.68Sc0.02In0.30W3O12.

The surface morphology of TiO2- and ZrO2-based thin films, deposited from aqueous solution at 70–80 °C onto functionalized organic self-assembled monolayers (SAMs) on silicon has been examined using atomic force microscopy (AFM). The films have been previously shown to consist, respectively, of nanocrystalline TiO2 (anatase) and of nanocrystalline tetragonal ZrO2 with amorphous basic zirconium sulfate. The films exhibit characteristic surface roughnesses on two length scales. Roughness on the nanometer scale appears to be dictated by the size of the crystallites in the film. Roughness on the micron scale is postulated to be related to several factors, including the topography of the SAM and the effects of larger, physisorbed particles or agglomerates. The topographies of the oxide thin films, on both the nanometer and micron scales, are consistent with a particle-attachment mechanism of film growth.

The effect of adding a few percent (3 at.%) Cu to Al films on the initial hillock formation and the changes in overall film stress were studied. Al films were evaporated by an electron-beam gun onto Si wafers in an ultrahigh vacuum deposition system and Al–Cu films were coevaporated with a thermally heated source used for the Cu. The as-deposited samples were radiatively heated at 3 °C/s in an air environment. During heating, the initial hillocking and the changes in overall stress were measured simultaneously and in real time with a specially designed optical instrument. The measurement principle of this instrument is based on laser beam deflection, caused by wafer bending due to film stress, and collection of the laser light scattered off from the hillocks appearing on the film surface. The experimental results show that Cu alloying has a strengthening effect on Al films, resulting in delayed and considerably reduced hillock formation. Before heating, the as-deposited Al–Cu samples were investigated by total integrated scattering and atomic force microscopy. These investigations showed that Al–Cu films are considerably smoother and have smaller grains than Al films of similar thickness (340 nm). It was found that the small grains of Al–Cu films contribute to increasing the tensile stress–temperature slope. In addition, Al–Cu films can withstand higher compressive stresses than Al films.

We report the first observation of large graphitic capped clusters with threefold symmetry (tripods). They were generated under the diamond growth conditions by the chemical vapor deposition process activated by hot filaments on a Cu(111) surface while conditions of very poor diamond nucleation (104–105 cm-2) are fullfilled. They were characterized by direct high resolution imaging and selected area diffraction. Furthermore, a lot of them are connected. The behavior of hydrogen radicals to curl and to close limited-size graphitic planes is emphasized to explain their formation. These tripods appear to be readily stable carbon as they form only after other limited-size graphitic clusters such as graphite lumps or bucky onions. It is thus expected that the chemical vapor deposition process is a quite relevant preparation method to grow in a controlled way new forms of carbon with a narrow size distribution.