The thermal stability of carbon nitride films, deposited by reactive direct current magnetron sputtering in N2 discharge, was studied for postdeposition annealing temperatures TA up to 1000 °C. Films were grown at temperatures of 100 °C (amorphous structure) and 350 and 550 °C (fullerenelike structure) and were analyzed with respect to thickness, composition, microstructure, bonding structure, and mechanical properties as a function of TA and annealing time. All properties investigated were found to be stable for annealing up to 300 °C for long times (>48 h). For higher TA, nitrogen is lost from the films and graphitization takes place. At TA = 500 °C the graphitization process takes up to 48 h while at TA = 900 °C it takes less than 2 min. A comparison on the evolution of x-ray photoelectron spectroscopy, electron energy loss spectroscopy and Raman spectra during annealing shows that for TA > 800 °C, preferentially pyridinelike N and –C≡N is lost from the films, mainly in the form of molecular N2 and C2N2, while N substituted in graphite is preserved the longest in the structure. Films deposited at the higher temperature exhibit better thermal stability, but annealing at temperatures a few hundred degrees Celsius above the deposition temperature for long times is always detrimental for the mechanical properties of the films.

Modification of Pb0.5Ca0.5[(Mg1/3Nb2/3)0.5Ti0.5]O3 dielectric ceramics was performed by up to 20 mol% La substitution for Pb and Ca. The temperature coefficient of dielectric constant was significantly reduced by the present approach, while an increased Qf factor was achieved. Good microwave dielectric properties were obtained in a composition Pb0.425Ca0.425La0.1[(Mg1/3Nb2/3)0.5Ti0.5]O3: ε = 125; Qf = 3150 GHz; calculated temperature coefficient of resonant frequency δf = +253 ppm/°C.

Ti, Fe, and Co ions were implanted in two ceramics, SiC and Si3N4, to reach concentrations on the order of 10% over a depth of about 50–60 nm. X-ray absorption spectroscopy was performed at the K edge of the implanted ions to identify their local environment at the end of the implantation process. Ti was found to form Ti–C and Ti–N bonds whereas Co and Fe precipitated and formed clusters in Si3N4. CoSi was detected in SiC whereas, in the same matrix, Fe clusters coexist with FeSi. A coherent interpretation of these results is given in terms of the heat of reaction for all possible systems. We also successfully interpret in the same way some results found in literature in the case of implanted oxides.

The sponge impregnation of water-based suspensions of hydroxyapatite powders synthesized by the coprecipitation method was investigated. The powder characteristics and slurry properties were correlated with the porosity and mechanical properties of the porous bodies obtained. The rheological characterization in the continuous flow condition revealed a strong dependence of the rheological behavior on the solid loadings particularly with high specific surface area powder. The behavior changed from newtonian to plastic, with pronounced hysteresis effects due to time dependency, by increasing the solids loading from 10 to 18 vol%. The morphology and distribution of the macropores could be related to the starting powder crystallinity and morphology as well as to the rheological properties of the suspensions. The compressive strength of the materials was strongly influenced by the porosity, while there was almost no dependence on the crystallinity of the powder. From a statistical viewpoint, the microporosity better explained the behavior of the mechanical strength than the total porosity.

The effects of Bi substitution for Nd in Ba6−3xNd8+2xTi18O54 (x = 2/3) solid solution upon the microstructures and microwave dielectric properties were investigated. The solid solubility limit of Bi in Ba6−3xNd8+2xTi18O54 (x = 2/3) solid solution was about 15 mol%, the same as that for x = 0.5, and densification of the present solid solutions could be performed well at lower temperatures. However, the variation tendency of microwave dielectric properties with composition in the present ceramics quite differed from that for x = 0.5: (1) The temperature coefficient of resonant frequency in the present ceramics showed a continuous variation from positive to negative and did not indicate extreme value at the solid solubility limit. (2) Near-zero temperature coefficient of resonant frequency combined with high-ε and high-Qf values could be obtained in the present ceramics, while that for x = 0.5 had a lower limit of +15 ppm/°C. (3) The dielectric constant also showed a continuous increase for the present compositions, while that in x = 0.5 had an extreme at solid solubility limit. Ceramics with composition of Ba6−3x(Nd0.85,Bi0.15)8+2xTi18O54 (x = 2/3) showed excellent dielectric properties of ε = 99.1, Qf = 5290 GHz, and τf = −5.5 ppm/°C.

A new analysis technique for calculating the hardness, modulus, and contact area from indentation data obtained using pyramidal or conical indenters was formulated and compared with another commonly used technique. Experimental data using a Berkovich indenter to indent fused silica and tungsten were examined. In addition, finite element modeling results were used to examine the effectiveness of the analytical techniques when a wide range of materials properties was considered. The new technique relies on the slope of the loading curve rather than the indenter displacement as an input. It is shown that the new technique is far less affected by the deviation of the geometry of the indenter from its intended shape. This effect removes the necessity to have detailed descriptions of the precise tip geometry in some cases. The new technique does not reduce errors associated with pile up of material near the indenter.

The subsolidus phase relations in the La–Fe–Al–O system were investigated for solid oxide fuel cell (SOFC) applications. Five compounds, LaAlO3, LaAl11O18, LaFe12O19, AlFeO3, and LaFeO3, coexist in the La–Fe–Al–O system at 1380 °C in air. The microstructure and composition of the samples were studied by x-ray diffractometry and scanning electron microscopy. Based on experimental evidence, a phase diagram of the La2O3–Al2O3–Fe2O3 system has been proposed.

A solid-state reaction mechanism for the formation of Ba6−xLn8+2x /3Ti18O54 (Ln = Nd, Sm) solid solutions has been studied using x-ray powder diffraction, thermal analyses, and transmission electron microscopy (TEM). During the interaction of the starting reagents, Ln2Ti2O7, BaTi4O9, and BaTiO3 are formed. In the next sequence, these three phases react together to form a high-x end member of the Ba6−xLn8+2x /3Ti18O54 homogeneity region (Ba3.9Nd9.4Ti18O54 and Ba3.9Sm9.4Ti18O54). Subsequently, the reaction of Ba3.9Nd9.4Ti18O54 and Ba3.9Sm9.4Ti18O54 with the residual BaTiO3 takes place. TEM investigations revealed that compositional inhomogeneities and structural defects existed in the Ba4Sm9.33Ti18O54 sample heated at 1370 °C for 1 h. Sintering times, prolonged to ≥3 h, eliminated the structural defects and increased the homogeneity of the sample.

Nanoindentation testing of the titanium oxide/titanium system with electrochemically grown oxide films exhibits permanent deformation prior to a yield excusion, indicating that the occurrence of this suddent discontinuity is predominantly controlled by oxide film cracking rather than dislocaton nucleation and multiplication. Observations of circumferential cracking also lend support to this explanation. A model has been developed to predict the mechanical response prior to oxide fracture for the case of a hard coating on a soft substrate. During loading contact, the hard coating undergoes elastic deflection which may include both bending and membrane stretching effects, while the substrate is elastoplastically deformed. The model works well for surface films thicker than 20 nm. Additionally, the maximum radial tensile stress in anodically grown titanium oxide, which is responsible for film cracking at the critical load, is approximately 15 GPa.

Carrier diffusivity has been experimentally determined in low-doped n-type epitaxial 4H–SiC over a wide injection range using a Fourier transient grating technique. The data showed that, with injection, the diffusion coefficient increased from a minority-hole diffusivity Dh = 2.3 cm2/s to an ambipolar diffusivity Da = 4.2 cm2/s at approximately 1016 cm−3 with a substantial decrease occurring at higher injections. The derived Dh value corresponded to a minority-hole drift mobility of μh = 90 cm2/Vs, about 30% lower than available majority-hole mobilities. Also, the temperature dependence of the ambipolar diffusivity in the 296–523 K range has been determined. It followed a power law Da ∼ T−1.3 which notably differed from the expected one using the majority-hole mobility temperature dependence.

In this work, a finite element method was performed to simulate the spherical indentation of a ductile substrate coated by a strong thin film. Our objective was to study indentation-induced delamination of the film from the substrate. The film was assumed to be linear elastic, the substrate was elastic–perfectly plastic, and the indenter was rigid. The interface was modeled by means of a cohesive surface. The constitutive law of the cohesive surface included a coupled description of normal and tagential failure. Cracking of the coating itself was not included. During loading, it was found that delamination occurs in a tangential mode rather than a normal one and was initiated at two to three times the contact radius. Normal delamination occurred during the unloading stage, where a circular part of the coating, directly under the contact area was lifted off from the substrate. Normal delamination was imprinted on the load versus displacement curve as a hump. There was critical value of the interfacial strength above which delamination was prevented for a given material system and a given indentation depth. The energy consumption by the delamination process was calculated and separated from the part dissipated by the substrate. The effect of residual stress in the film and waviness of the interface on delamination was discussed.

The crystallization and dielectric properties of SrO–BaO–Nb2O5–GeO2 glass–ceramics were investigated. One- and two-stage heat-treatment methods were used to convert the parent glass to glass–ceramics. Strontium barium niobate (SBN) with a tetragonal tungsten-bronze structure formed as the major crystalline phase. When the crystallizing temperature/time was increased, the secondary crystalline BaGe2O5 phase coexisted with SBN. BaGe2O5 formed as a surface layer grown from the surface into the interior of the sample. The dendritic morphology of SBN crystals was examined. The glass–ceramics crystallized by two-stage heat treatment have higher dielectric constants than those crystallized by one-stage heat treatment. The highest dielectric constant that was obtained in the present glass–ceramics was 320. The glass–ceramics showed relaxor-type dielectric behavior.

A new route, based on the use of ionic calcium phosphate cements, has been developed to synthesize hydroxyapatite. Cements were prepared from tetracalcium phosphate, α–tricalcium phosphate, phosphoric acid, strontium nitrate, and water. They were then mixed and shaped. Cements with various amounts of strontium and different (Ca + Sr)/P atomic ratios were prepared. All the materials obtained were coherent and solid. When the amount of strontium was low, mixed hydroxyapatite was obtained at low temperatures. Mixed calcium strontium apatite was obtained after heating. This original method can be of interest in various fields such as biomaterials or the storage of radioactive waste.

The heterogeneous photocatalytic oxidation of rhodamine B in aqueous solution containing pure or zinc (iron)-doped titania films has been studied. N-deethylation of rhodamine B was accelerated by iron(III) and zinc(II) doping as compared with pure titania film. It is shown that improvement of electron transfer from dye molecules to the film may be responsible for the high N-deethylation rate for iron-doped (0.5 mol%) film, while for zinc-doped (20 mol%) film, high surface roughness may be the main reason. In addition, both iron and zinc doping brought a new shallow trap to the intragap meaning that the surface defects had increased after doping; this is a possible reason doped films present relative low photoreactivity to catalyze the direct degradation of dye molecules.

SrBi2Ta2O9 (SBT) films were prepared on Pt/TiO2/SiO2/Si substrates at 750 °C in oxygen by the metalorganic decomposition method. SBT film capacitors were postannealed in Ar (N2) at 350–750 °C and then reannealed in O2 at 750 °C. Effects of annealing atmosphere on the structure, morphology, and ferroelectric properties have been investigated systematically. The composition analyses indicate Ar- or N2-annealing at 750 °C leads to Bi evaporation and oxygen loss. Above 550 °C 100% Ar or N2 postannealing, the remnant polarization decreases and the coercive field increases significantly. The subsequent O2 recovery can hardly rejuvenate the electrical properties. The result is different from that with the effective O2 recovery in forming gas processing (annealing in an atmosphere containing 5% hydrogen). The possible origin and mechanism is discussed and proposed.

An elastic-plastic crystalline constitutive model implemented in a finite-element code has been used to predict the microscale thermal residual stresses in Al−1%Si−0.5%Cu interconnects. This fully three-dimensional model accounts for the individual grain orientations in these interconnects, as measured by orientation imaging microscopy. The influence of specific crystal orientations on the residual stress distribution in these interconnects was studied in detail. A sensitivity analysis was performed to identify the parameters that influence strongly the predicted values of the residual stresses and their distributions. For the interconnects studied here, the residual stresses in the metal lines were found to be quite sensitive to the elastic modulus of the passivation material and its geometry. In addition, the volume averages of the predicted stresses were in reasonable agreement with the experimentally determined values from the x-ray technique.

The influence of the RuO2 bottom electrode microstructure on the texture and ferroelectric properties of sol-gel PZT in RuO2/PZT/RuO2/Pt capacitors is discussed. For high growth temperatures, RuO2 has a columnar microstructure and a mixed (100)/(110) texture, attributed to epitaxial growth on Pt(111) and TiO2 (110) grains of the preannealed Pt / Ti layer. The mixed orientation of RuO2 resulted in a mixed PZT texture and slanted ferroelectric hysteresis characteristic. As the RuO2 growth temperature was reduced, the microstructure of the RuO2 layer turned to fine-grained equiaxed, with a grain size of approximately 10 nm, and PZT developed a sharp (111) texture (I111/I100 > 100) resulting in a rectangular hysteresis characteristic and a remanent polarization >30 μC/cm2. The emergence of a strong (111) fiber texture in PZT on fine-grained RuO2 shed new light on the orientation selection mechanisms in sol-gel-prepared PZT layers. Possible applications of this phenomenon for high-density ferroelectric memories with a stacked layout are briefly discussed.

According to resonant vibration fatigue tests, near-eutectic and Pb-rich hypoeutectic Pb–Sn specimens have higher crack-propagation resistance. The tensile flow stress of Pb–Sn solders that are near eutectic composition increases with decreasing Pb content. The solders were tested after either stabilizing at 373 K or natural aging for 20 days, which gave similar results. The naturally aged specimens show that the crack-propagation resistance increases with increasing aging time. A striated deformation was found to occur in Sn grain of the lower Pb specimen. This phenomenon is correlated with a deterioration of crack-propagation resistance.

Directional solidification using a Bridgman furnace was performed to produce textured Y2BaCuO5 (211) rods of both stoichiometric and off-stoichiometric compositions and to investigate microstructure formation at various solidification rates. The solidification morphology of the samples changed from planar to cellular and eventually to equiaxed blocky grains with increasing solidification rate. The microstructure of the stoichiometric 211 sample revealed elongated, aligned YBa2Cu3Oy (123) phase residual in the 211 matrix. The 211 samples rich in Y2O3 phase showed no trace of residual 123 but did show trapped Y2O3 particles. The morphology of the Y2O3 particles varied from spherical to a rodlike morphology as well along the length of a specific sample as also with decreasing growth rates in different samples. The Y2O3 particles in samples exposed for longer time to the liquid phase at high temperatures exhibited coarsening and unidirectional coalescence into a rodlike morphology and retained their morphology even in the 211 matrix after solidification.

Polycrystalline Ce0.77Nd0.23O1.885 having a relative density in excess of 98% was prepared. Oxygen diffusion experiments were performed for the temperature range from 750 to 1100 °C, in an oxygen partial pressure of 6.6 kPa. The concentration profile of 18O in the specimens following diffusion annealing was measured by secondary ion mass spectroscopy (SIMS). The oxygen self-diffusion coefficient obtained using secondary ion mass spectrometry was expressed by D = 6.31 × 10−9 exp(−53 kJ mol−1/RT) m2 s−1 and was in the extrinsic region. The oxygen diffusion coefficient of Ce0.77Nd0.23O1.885 was larger than that of Ce0.8Y0.2O1.90; it was close to those of Ce0.6Y0.4O1.80 and Ce0.69Gd0.31O2−δ. The oxygen diffusion coefficient obtained by the tracer method at 700 °C agreed with that calculated from the electrical conductivity in Ce0.77Nd0.23O1.885. The activation energy of the surface exchange coefficient was 94 kJ mol−1, and the values of the surface exchange coefficient were similar to those of stoichiometric CeO2 and ThO2.