Dielectric ceramics in the BaO–Sm2O3–TiO2–Ta2O5 quaternary system were prepared and characterized for five typical compositions: BaSm5Ti7Ta3O30, Ba2Sm4Ti6Ta4O30, Ba3Sm3Ti5Ta5O30, Ba4Sm2Ti4Ta6O30, and Ba5SmTi3Ta7O30. The latter three compositions tended to form the tungsten–bronze phase, and the ceramics based on these compositions had a high dielectric constant (134–175) and a low dielectric loss (on the order of 10−3) but a larger temperature coefficient of the dielectric constant. Meanwhile, the former two compositions generally had a more complex phase constitution, containing the tungsten–bronze phase combined with some unknown phase, and a relatively small temperature coefficient of the dielectric constant in the temperature range of 20 to 85 °C could be achieved in these two compositions.

Silicon nitride with the aligned reinforcing grains was prepared by tape casting with addition of the silicon nitride whiskers and gas-pressure sintering at 2148 K. The microstructure and the mechanical properties of the sintered sample, including the fracture toughness and the three-point flexural strength, were highly anisotropic. Both the fracture toughness and the flexural strength were the highest when the crack-propagation direction was normal to the alignment direction. This result was interpreted from the laminate composite materials’ point of view. Although the large elongated grains were as long as 44.4 ± 12 μm and as wide as 5.1 ± 0.67 μm, they were not the fracture origins.

A refractory silicon nitride joint, which contains β–Si3N4 grains and grain boundary amorphous phase in the joined layer, was developed with the aid of a ceramic adhesive based on the system Si3N4–Y2O3–SiO2–Al2O3. The similarity in chemistry and microstructure between the parent ceramic and the joint zone indicates that the joining mechanism is the same as that involved in the sintering of Si3N4. The resultant joint exhibits a high bond strength of 550 MPa at 25 °C and retains a strength of 332 MPa at 1000 °C. Post-joining hot-isostatic pressing was applied to strengthen the joint, resulting in increased strengths of 668 MPa at room temperature and 464 MPa at 1000 °C.

The fracture behavior of high-purity alumina ceramics with grain sizes ranging from 2 to 13 μm is studied by means of the double torsion method. Crack-propagation tests conducted in air, water, and silicon oil, for crack velocities from 10−7 to 10−2 m/s, show that slow crack growth is due to stress corrosion by water molecules. An increase of the grain size leads to enhanced crack resistance, which is indicated by a shift of the V–KI (crack velocity versus applied stress intensity factor) plot toward high values of KI. Moreover, the slope of the curve is apparently higher for coarse grain alumina. However, if the R-curve effect is substracted from the experimental results, a unique V–KItip (crack velocity versus stress intensity factor at the crack tip) law is obtained for all alumina ceramics, independently of the grain size. This means that the crack-growth mechanism (stress corrosion by water molecules) is the same and that the apparent change of the V–KI law with grain size is a direct effect of crack bridging.

We investigated sol-gel-derived silica-based hard coatings on modified polyester substrates. The silica network was modified by incorporating an organic component and adding transition metal oxides. These modifications resulted in tailored thermal, optical, and mechanical properties of the coatings. Various low-temperature densification techniques were studied including sol-preparation procedure, enhanced solvent evaporation, ultraviolet irradiation, and low-temperature heating (below 150 °C). Oxygen plasma etching was applied to improve the adhesion of the sol-gel coatings on the plastic surface. Nanoindentation analysis revealed that the coatings have a surface hardness up to 2.5 ± 0.27 GPa and an elastic modulus up to 13.6 ± 0.4 GPa, approximately an order of magnitude higher than that of the plastic surface.

Si3N4 powders manufactured by two different preparative routes were characterized for the solid–liquid interfacial reactivity and surface composition. Three mixing processes were tried to investigate the modifications of silicon nitride particle surface in aqueous suspensions. The surfaces of the starting powders and the dried mixed powders were investigated by x-ray photoelectron spectroscopy to determine the nature and ratios of surface groups. Electroacoustic measurements show that no change occurs in the isoelectric point for the mixed Si3N4 powders while the milling/mixing process has a great influence on the zeta potential magnitude and particle size distribution.

Three mixing processes were used to introduce lanthanum oxide and yttrium oxide in silicon nitride suspensions. X-ray photoelectron spectroscopy (XPS) analysis was used to identify the surface composition and investigate the surface coverage by the added oxides. XPS results evidenced the protective effect against hydrolysis and oxidation of the coated layer. Electroacoustic measurements showed that the milling/mixing process and solids loading contents had a great influence on the isoelectric point (IEP) and on the dispersing degree for suspensions with sintering aids. With the change of solids load content and mixing energy, the IEP of mixed powders suspensions reflected a surface behavior dominated by the additives oxides. The attrition mixing and the ultrasonication resulted in the more efficient processing routes to distribute the sintering aids on the starting Si3N4 powders, especially at high solids volume fraction.

Ultrafine MnFe2O4 powder with its crystallites less than 100 nm was prepared using a combustion process. The coprecipitates containing the stoichiometric amount of Mn2+ and Fe3+ to form MnFe2O4 were prepared by dissolving the required metallic nitrates in de-ionized water and adding NH4OH to adjust the pH of the solutions to 9. The collected dried precipitates were then heated up to predetermined temperatures and then quickly contacted with the acetone spray. Upon contacting with the heated precipitates, the acetone spray was ignited. The combustion of acetone caused the precipitates to form crystalline MnFe2O4 without chemical segregation. The crystallinity of MnFe2O4 powder so obtained depended on the ignition temperature of acetone spray. MnFe2O4 powder obtained at acetone ignition temperature of 773 K had higher crystallinity than that obtained at acetone ignition temperature of 523 K. The presence of a small amount of Mg2+ or Zn2+ in the composition of the coprecipitates promoted the mobility of constituent ions of the combusted powder and resulted in bigger MnFe2O4 crystallites at a lower acetone ignition temperature.

Spherical alumina particles were prepared following the sol-emulsion-gel method by systematic variation of (i) the concentration of the surfactant Span 80 above or below the critical micelle concentration (CMC) in different organic solvents and (ii) hydrophilic–lipophilic balance (HLB) of different surfactants in cyclohexane. The experimentally determined CMC of Span 80 was found to increase with increasing dielectric constant of the organic solvent, influencing the sol droplet and alumina particle size. With an increase in the HLB value of the surfactants, the tendency of monodispersed sphere formation among the particles increased with a decrease in the size distribution and average particle size (d50).

The metastable immiscibility region in the Al2O3–SiO2 system was calculated by conventional thermodynamic equations using thermodynamic parameters obtained from molecular dynamics simulation. The calculated miscibility gap has a consolute temperature of around 1500 °C at the critical composition of about 20 mol% Al2O3 and spreads more widely towards the Al2O3-rich composition side than the SiO2-rich side. The calculated miscibility gap in this study showed a fair agreement with that reported by Ban et al. [T. Ban, S. Hayashi, A. Yasumori, and K. Okada, J. Mater. Res. 11, 1421 (1996)] calculated by a regular solution model, but the present calculated region is somewhat narrower in the Al2O3-rich composition side than that reported by Ban et al.

We have demonstrated that the optimum Ta–Si–N compositions for use as oxygen diffusion barriers in stacked-capacitor dynamic random-access memory structures with perovskite dielectrics are in the range Ta(20–25 at.%)–Si(20–45 at.%)–N(35–60 at.%). Twenty-two different Ta–Si–N compositions were evaluated, starting from six sputter-deposited Ta–Si alloys of which four were reactively deposited in 2–8% nitrogen in an argon plasma. The barriers were evaluated after an aggressive 650 °C/30 min oxygen anneal to determine if they remained electrically conductive, prevented oxygen diffusion and formation of low dielectric constant oxides, and had minimal interaction with the Pt electrode and underlying Si plug. Rutherford backscattering spectroscopy, four-point probe sheet resistance, through-film-resistance, and x-ray diffraction analysis techniques were used in the evaluation.

Pb(Zr0.52Ti0.48)O3 thin films were grown on p-InP (100) substrates by using radio-frequency magnetron-sputtering at a relatively low temperature (∼450 °C). X-ray diffraction measurements showed that the Pb(Zr0.52Ti0.48)O3 film layers grown on the InP substrates were polycrystalline, and Auger electron spectroscopy measurements indicated that the compositions of the as-grown films consisted of lead, zirconium, titanium, and oxygen. Transmission electron microscopy measurements showed that the grown Pb(Zr0.52Ti0.48)O3 was a polycrystalline layer with small domains and that the Pb(Zr0.52Ti0.48)O3/InP (100) heterointerface had no significant interdiffusion problem. Room-temperature current–voltage and capacitance–voltage (C–V) measurements clearly revealed a metal–insulator–semiconductor behavior for the Pb(Zr0.52Ti0.48)O3 insulator gates, and the interface state densities at the Pb(Zr0.52Ti0.48)O3/p-InP interfaces, as determined from the C–V measurements, were approximately low 1011 eV−1 cm−2 at an energy of about 0.6 eV below the conduction-band edge. The dielectric constant of the Pb(Zr0.52Ti0.48)O3 thin film, as determined from the C–V measurements, was as large as 907.2. These results indicate that the Pb(Zr0.52Ti0.48)O3 layers grown on p-InP (100) substrates at low temperatures hold promise for potential high-density nonvolatile memories and high-speed infrared sensors based on InP substrates.

With the advent of copper metallization in interconnect structures, new barrier layers are required to prevent copper diffusion into adjacent dielectrics and the underlying silicon. The barrier must also provide adequate adhesion to both the dielectric and copper. While Ta and TaN barrier layers have been incorporated for these purposes in copper metallization schemes, little quantitative data exist on their adhesive properties. In this study, the critical interface fracture energy and the subcritical debonding behavior of ion-metal-plasma sputtered Ta and TaN barrier layers in Cu interconnect structures were investigated. Specifically, the effects of interfacial chemistry, Cu layer thickness, and oxide type were examined. Behavior is rationalized in terms of relevant reactions at the barrier/dielectric interface and plasticity in adjacent metal layers.

The influence of the carbon network structure of polycrystalline diamond films that were prepared from a mixture of H2, CH4, and N2 using microwave-enhanced plasma chemical vapor deposition on electron field emission has been systematically investigated. With increasing nitrogen gas flow ratio of [ N2]/[H2 + CH4 + N2], the film hardness and surface roughness of the as-grown films decreased, and the concentration ratio of amorphous sp2-bonded carbon clusters and mixed sp2−sp3 carbon structures to tetrahedrally bonded amorphous carbon phases increased. Correspondingly, the turn-on voltage for electron emission decreased. After the surface post-treatment by pure hydrogen plasma exposure, the concentration ratio was clearly found to have increased dramatically and the turn-on voltage decreased significantly for the films produced at small nitrogen flow ratio. Our results suggest that the influence of the concentration ratio on electron field emission is much more significant than that of the surface roughness of the polycrystalline diamond films studied in this paper.

The role of Fe2O3in the structural and physical properties of ternary lead vanadium iron glass system has been studied in comparison with the binary lead vanadate glasses. X-ray diffraction, scanning electron microscopy, and differential thermal analysis show that homogeneous glasses of composition 10Fe2O3 · xV2O5 · (90 − x)PbO can be obtained for x = 50 to 80 mol%. Observation from the infrared spectroscopy shows that the basic building blocks of these glasses are same as those of crystalline V2O5, while differential thermal analysis and electrical conduction of these glasses suggest that there is a strong role of iron, both in the glass network and in the conduction mechanism for the glasses containing a low percentage of vanadium.

The effect of crystallization on microwave dielectric properties of cordierite glasses containing B2O3 and P2O5 additions was investigated. Two glasses containing 5 wt% B2O3/5 wt% P2O5 and 7.5 wt% B2O3/7.5 wt% P2O5 were studied. Both glasses were sintered to nearly full density at temperatures as low as 860 °C. The frequency constant and quality factor of α cordierite are, respectively, about five times and two times larger than those of glassy phase and μ cordierite. The temperature coefficients of resonant frequency are estimated to be about −13, −55, and −15 ppm/°C for glassy phase, μ cordierite, and α cordierite, respectively. As a result of the microwave dielectric properties of the individual phase, cordierite glasses containing α cordierite possess the best microwave properties.

Effects of plasma power on the properties of polymerlike organic thin films deposited by plasma-enhanced chemical vapor deposition using the toluene precursor were studied. As the plasma power was increased from 5 to 60 W, the relative dielectric constant increased from 2.53 to 2.85. The film deposited at higher plasma power showed higher thermal stability. The film deposited at 60 W was stable up to 400 °C. All the films were insulating under applied field ≤1 MV/cm.

A silklike protein with fibronectin functionality (SLPF) (ProNectin F®, Protein Polymer Technologies, Inc.) is a genetically engineered protein polymer containing structural and biofunctional segments. The mechanical properties and deformation mechanisms of electrostatically deposited SLPF thin films were examined by scratch testing, tensile testing, and nanoindentation. Scanning electron microscopy and scanned probe microscopy revealed that the macroscopic properties were a sensitive function of microstructure. The SLPF films were relatively brittle in tension, with typical elongation-to-break values of 3%. Nanoindentation data were fit to a power law relationship.

The oxidative stability of poly(butylene terephthalate) was investigated over the range 175 to 220 °C by isothermal differential calorimetry. It is shown that this property is affected by a fast recrystallization process, which takes place between 200 and 220 °C, with a maximum around 208 °C. In fact, recrystallization produces an increase of the crystallinity degree of the polymer, which enhances its resistance to oxidation, as proven by the longer oxidation times detected.

Further experimental observations have allowed us to refine and confirm some aspects of our recently proposed mechanism for reactive diffusion between Si single crystal and NbC powder compact, particularly regarding the prediction of Si as the dominant diffusing species and the nature of the dependence of SiC particle morphology on the presence of voids in the NbC end member. In Si|NbC diffusion couples annealed at either 1300 or 1350 °C, a two-phase NbSi2 + SiC reaction layer formed. Although NbSi2 was the matrix in all of the reaction layers, the SiC phase morphology depended upon NbC porosity: when high-porosity NbC was used, SiC was present as discontinuous particles greater than 1-μm-across, while when low-porosity or void-free NbC was used, SiC grew cooperatively with NbSi2 in the form of lamellae less than 0.5 μm thick. We propose that this difference arises from the effect of voids both as nucleation sites for SiC particles and as channels for unrestricted SiC growth. Marker experiments conclusively show that Si is the dominant diffusing species in the reaction layer.