In order to clarify inconsistencies in the literature and to verify assumed ternary solubilities, the phase equilibria in the Y2O3–Al2O3 –SiO2 system at 1600, 1400, and 1300 °C were experimentally determined using x-ray diffraction (XRD), scanning electron microscope with attached energy-dispersive detector system (SEM-EDX), and electron probe microanalyzer (EPMA). Six quasibinary phases were observed: Y4Al2O9 (YAM), YAlO3 (YAP), Y3Al5O12 (YAG), Y2SiO5, Y2Si2O7 (C and D modifications), and ˜3Al2O3· 2SiO2 (mullite). Y4Al2O9 forms an extended ternary solid solution with the formula Y4Al2(1-x)Si2xO9+x (x = 0 2 ˜0.31). The lowest ternary eutectic temperature was determined at 1371 ± 5 °C by high-temperature differential scanning calorimetry (DSC). The results were compared with previous data available for the Y2O3–Al2O3 –SiO2 system and with data for other RE2O3–Al2O3 –SiO2 (RE = rare earth element) systems.

Powder x-ray diffraction data of yttria (Y2O3) were obtained from room temperature to melting point with the thin wire resistance heating technique. A solid-state phase transition was observed at 2512 ± 25 K and melting of the high-uemperature phase at 2705 ± 25 K. Thermal expansion data for α–Y2O3 (C-type) are given for the range 298–2540 K. The unit cell parameter increases nonlinearly, especially just before the solid-state transition. The x-ray diffraction spectrum of the high-temperature phase is consistent with the fluorite-type structure (space group Fm3) with a refined unit cell parameter a = 5.3903(6) Å at 2530 K. The sample recrystallized rapidly above 2540 K, and above 2730 K, all the diffraction lines and spots disappeared from the x-ray diffraction spectrum that suggests complete melting.

Crystals of (Ca1.95□0.05) (Si0.9P0.1)O4, where □ denotes a vacancy, composed of both the α′L and β phases, were prepared and examined by the precession method. The β phase was exclusively twinned on (100)β, and the relative volumes of the twin-related variants were almost identical with each other. On the basis of the lattice correspondence between the two phases and their cell parameters, the phenomenological crystallographic theory was applied to determine the habit planes and the shape deformations upon α′L-to-β martensitic transformation. The habit planes, which define the coherent interphase boundaries between α′L and β, were nearly parallel to either (100)α′L or (010)α′L·. The alternate shape deformations that produce the former habit planes resulted in the actual (100) twin structure of the β phase. The total displacement was along [100]α′L with the magnitude of 0.008. Because the transformation involved a very small volumetric shrinkage of 0.6%, the strain accommodation would be almost completed. The coherency at the interface boundaries between the two phases and the effective strain accommodation probably caused the thermoelasticity of the Ca2SiO4 solid solutions.

Studies of the structure-property relations of lead zirconate titanate (PZT) modified with lower valent substitutions on the A- and B-sites have been performed as a function of substituent concentration. These investigations have yielded common changes induced by these substitutions on ferroelectric phases. The commonalties are the presence of fine domains and polarization pinning effects. Differences in domain morphologies were observed between the rhombohedral and tetragonal ferroelectric phases. Rhombohedral ferroelectrics were found to exhibit “wavy” domain patterns with increasing dopant concentrations, whereas a lenticular domain shape was preserved as the domain size was decreased for tetragonal ferroelectrics. These differences were explained in terms of different pinning mechanisms based on the differences in local elastic strain accommodations. Investigations of high Zr-content PZT have revealed that the ferroelectric rhombohedral phase becomes stabilized over the antiferroelectric orthorhombic with increasing concentrations of lower valent modifications. This change was explained in terms of the enhanced coupling between oxygen octahedra due to the bonding of oxygen-vacancy dipoles.

The effect of the additive KCl, on the structural, microstructural, and polar properties of bismuth vanadate (BiV) ceramics is investigated. The scanning electron microscopic (SEM) studies reveal a remarkable modification in the microstructure and the occurrence of high grain-orientation (75%) on KCl addition. The energy dispersive x-ray (EDX) analyses indicate the presence of chemically inhomogeneous distribution of KCl, with core-shell-like grain structure. The KCl-modified BiV samples exhibit a broad and depressed phase transition, with no frequency dispersion, as a result of the increased internal stress and the formation of core-shell-like grain structure. Significant anisotropies are observed in the dielectric, piezoelectric, and pyroelectric responses of these grain-oriented ceramic samples. These samples are characterized by near rectangular ferroelectric hysteresis loops, with a significant anisotropy in the Pr (Pr┴/Pr∥ = 2.43, at 300 K) and Ec (Ec∥/Ec┴= 2.22, at 300 K) values between the directions parallel and perpendicular to the cold-pressing axis.

Ferroelectric Pb(Zr, Ti)O3 (PZT) thin films were grown on Pt/Ti/SiO2/Si, RuO2/Pt/Ti/SiO2/Si, and Pt/MgO substrates at the substrate temperature of 600 °C by the metalorganic chemical vapor deposition (MOCVD) method. Pb(C11H19O2)2(Pb(DPM)2), Ti(OiC3H7)4, and Zr(OtC4H9)4 as source material and Ar and O2 as a carrier gas and oxidizing agent were selected, respectively. In order to investigate the effect of Zr and Ti component changes on the growth aspect of PZT thin films, Zr and Ti source materials were varied by controlling Zr and Ti flow rate. From the Rutherford backscattering spectroscopy (RBS) measurement, it was confirmed that the composition of the films, particularly Pb content, changed with the increasing Zr flow rate. In addition, the x-ray diffraction (XRD) spectra analysis showed the existence of a Pb-deficient pyrochlore phase as well as ZrO2 as a secondary phase. From these results, it is believed that the higher Zr partial pressure in the gas phase reduces the sticking of the Pb precursor to the substrate. The film with Pb:Zr:Ti = 1:0.42:0.58 showed a dielectric constant of 816 at 1 MHz. The spontaneous polarization, remanent polarization, and coercive field measured from the RT66A by applying 3.5 V were 44.1 μC/cm2, 24.4 μC/cm2, and 59.6 kV/cm, respectively. The fatigue analysis of PZT thin films with Pb:Zr:Ti = 1:0.42:0.58 at an applied voltage of Vp-p = 5.4 V showed 40% degradation on the basis of initial polarization value after 109 cycles.

0.53Ti0.47)O3 have been prepared on platinized GaAs (Pt–GaAs) substrates using a new 1,1,1-tris(hydroxymethyl)ethane (THOME) based sol-gel technique. Rapid thermal processing (RTP) techniques were used to decompose the sol-gel layer to PZT in an effort to avoid problems of GayAs outdiffusion into the PZT. A crystalline PZT film was produced by firing the sol-gel coatings at 600 or 650 ° for a dwell time of 1 s using RTP. A single deposition of the precursor sol resulted in a 0.4 μm thick PZT film. X-ray diffraction measurements revealed that the films possessed a high degree of (111) preferred orientation. Measured average values of remanent polarization (Pr ) and coercive field (Ec) for the film annealed at 650 ° for 1 s were 24 μC/cm2 and 32 kV/cm, respectively, together with a low frequency dielectric constant and loss tangent at 1 kHz of 950 and 0.02. These values are comparable to those obtainable on platinized silicon (Pt–Si) substrates using conventional sol-gel methods, and are an improvement on PZT thin films prepared on platinized GaAs using an earlier sol-gel route based on 1,3-propanediol.

It has been generally accepted that the product of the unloaded quality factor and resonant frequency is the universal parameter for comparison of dielectric resonators with different size.1,2 However, it is suggested in this study that this universal parameter should be modified due to the presence of the polarons. From the frequency dependence of the unloaded quality factor, it is possible to extract the factor determined only by the phonon scattering effects, and we denoted this parameter by Qs. It was found that the Qs parameter for ZrxSnzTiyO4 (ZST) and Ba(Zn1/3Ta2/3)O3 (BZT) ceramics showed constancy in the frequency range of 2–12 GHz, which supports the idea of polaron conduction loss contribution to the dielectric loss.

Self-assembling of size, shape, and phase-selected nanocrystals into superlattices in a new approach for synthesizing a new generation of advanced materials with functionality. In this paper, high purity and monodispersive tetrahedral of CoO, with edge lengths of 4.4 ± 0.2 nm, have been synthesized and separated from Co nanocrystals using colloidal chemistry and magnetic separation. The tetrahedral CoO nanocrystals behave like a molecular matter, and their assembling forms superlattices with translational symmetry. The phase transformation of the CoO nanocrystals is examined by ex situ annealing in oxygen, and the results showed the formation of Co3O4 with spinel structure.

Two kinds of high-purity Al2O3 powder were studied with respect to the effects of not only MgO doping but also atmosphere on both densification and grain growth. Controversial results for MgO doping are explained in terms of two roles that MgO can play during these processes: sensitive and insensitive to the experimental procedures. Atmospheres, whether dry or wet, had little influence on densification or grain growth in the early stage. After closed pores appreciably formed, however, both N2 and Ar atmospheres quickly reduced the densification rate.

6H(α)-SiC fine powder was sintered at normal pressure with additives of between 0.67 to 2.7 wt.% of AlB2 and 2 wt.% of C. The powder could be densified at 1850 °C. This sintering temperature was lower than that for SiC with B and C additives by 150–300 °C. During sintering, 6H-SiC partially transformed into 4H-SiC, and the transformation caused grain to grow and develop a nonspherical shape. The fracture toughness of sintered SiC increased with increases in the amount of AlB2 additive, the mean grain size, and the mean aspect ratio of grain shape. AlB2 and C additives are believed to have formed an Al8B4C7 compound which melted below 1800 °C and enhanced sintering and grain growth.

Compressive creep of dense BaTiO3 having linear-intercept grain sizes of 19.3–52.4 μm was investigated at 1200–1300 °C by varying the oxygen partial pressure from 102 to 105 Pa in both constant-stress and constant-crosshead-velocity modes. Microstructures of the deformed materials were examined by scanning and transmission electron microscopy. The stress exponent was ≈1, the grain-size dependence was ≈1/d2, and the activation energy was ≈720 kJ/mole. These parameters, combined with the microstructural observations (particularly grain displacement and absence of deformation-induced dislocations), indicated that the dominant deformation mechanism was grain-boundary sliding accommodated by lattice cation diffusion. Because of the absence of an oxygen partial pressure dependence, diffusion was probably controlled extrinsically.

CaSiO3 powders were prepared from an ethanol solution dissolving Ca(NO3)2 · 4H2O and Si(OC2H5)4 by the coprecipitation method using various concentrations of NaOH as precipitants. Some Na component remained in the precipitates without washing and strongly affected the characteristics of the resultant powders, but the Na residue was removed by a washing treatment. The precipitate prepared by using 0.33 mol/l of NaOH and twice-washing contained the lowest amount of Na residue. It was calcined at 500 and 900 °C, respectively, to crystallize CaSiO3 phase and ground by a planetary potmill. The ground CaSiO3 powder was sintered to about 89% theoretical density by firing at 1400 °C. By soaking the CaSiO3 sintered bodies in simulated body fluid (SBF) solution for various times, an hydroxylapatite (HAp) layer formed as aggregates of ball-like particles on the surface of the CaSiO3 sintered bodies after soaking for a short period; thereby, the CaSiO3 ceramics is suggested to have very good biocompatibility.

Using inorganic chemicals, such as niobium pentachloride, titanium tetrachloride, lead nitrate, and magnesium nitrate, as the starting materials, 0.9PMN–0.1PT has been fabricated via a simple and low cost sol-gel processing route. A colloidal solution was first prepared by adding an aqueous lead nitrate solution into an ethanol solution of niobium and titanium chlorides. Magnesium nitrate was then mixed into the solution when chloride ions were removed by forming precipitates of PbCl2 with the excess lead nitrate. The gelation of the colloidal solution was facilitated in the presence of a small amount of polyethylene glycol (PEG 300) at 70 °C. A fine perovskite 0.9PMN–0.1PT powder was obtained when the resulting gel was dried at 300 °C for 4 h and subsequently calcined. It was observed that the sol-gel derived precursor underwent a pyrochlore phase at 500–600 °C, prior to the formation of a perovskite single phase at a calcination temperature of 850 °C. A sintered density of ˜98% theoretical density was obtained when the fine 0.9PMN–0.1PT powder was sintered at 1250 °C for 2 h and the sintered ceramic shows a maximum dielectric constant of 26,682, together with a room temperature dielectric constant of 19,206 at 1 kHz. The superb dielectric properties are correlated to the microstructural features of the sol-gel derived 0.9PMN–0.1PT, which has been characterized using techniques such as XRD, SEM, and TEM.

The effect of La2O3 substitutions on structure and dielectric properties of Bi2O3 –ZnO–Nb2O5-based ceramics was investigated. Bi1.5-xLaxZn0.5(Zn0.5Nb1.5)O7 samples were prepared by conventional ceramic processing technology. The crystal structure of the Bi1.5Zn0.5(Zn0.5Nb1.5)O7 sample was characterized as a pure cubic pyrochlore. With a lower amount of La2O3 substitution, the crystal structures were still cubic pyrochlore. Superlattice x-ray diffraction line was identified for some compositions. With the increasing amount of La2O3 substitution, the crystal structure gradually transformed from pure cubic pyrochlore to LaNbO4 phase. The dielectric properties regularly changed with the structure change. The structure-properties relations of the ceramics are discussed.

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.

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.

In order to make the surface of chemically vapor deposited diamond (CVDD) substrates amenable to metallization by both thin and thick film approaches currently utilized in electronic packaging, a thin, adherent, insulating aluminum oxide film was grown on diamond at low temperatures (<675 K). The film was produced by reactive thermal evaporation of Al and O in an oxygen atmosphere, followed by low-temperature annealing in oxygen. A Cr intermediate layer was deposited on diamond prior to the deposition of aluminum oxide in order to enhance adhesion between the oxide and diamond. The chemistry, crystal structure, and microstructure of the film were characterized in detail via scanning and transmission electron microscopy, as well as Auger electron spectroscopy. Particular attention was given to the mechanisms of bonding across the CVDD-Cr and Cr-alumina interfaces, as well as the stability of the surface treatment following metallization by fritted pastes requiring firing at elevated temperatures. The Cr was found to be bonded with CVDD by Cr23C6 formation, while the bonding between the Cr and alumina layers was provided by the formation of a compositionally modulated solid solution with Al2O3-rich and Cr2O3-rich regions.

A 13.56 MHz low pressure inductively coupled plasma (ICP) has been applied to prepare diamond films. The Faraday shield drastically suppressed the electrostatic coupling, which frequently causes contamination due to the etching of the quartz tube. The characterizations of the obtained deposits by scanning electron microscopy (SEM), transmission electron diffraction (TED), and reflection high energy electron diffraction (RHEED) revealed that the deposits are composed of microcrystalline diamond and disordered microcrystalline graphite. The CO additive to a CH4/H2 plasma brought about the morphological change from a scale-like deposit to a particle one. Besides, the number of encountered particles was increased with an increase of CO additive. The TED and RHEED observations showed that non-diamond carbon was effectively removed with an increase of CO additive. These results indicate that oxygen-contained radicals produced by the addition of CO play an effective role in the removal of non-diamond carbon in the diamond growth conditions and that the CO additive makes the supersaturation degree of carbon large.

A micromechanical model of void nucleation in passivated metal interconnection lines is proposed. The model is based on the evolution of stress and strain fields in a two-dimensional model system, obtained from numerical modeling. Interface flaws in the form of debond between the metal and the surrounding dielectric are assumed to exist. A unique pattern of shear stress resolved on the slip systems in the metal line, due to the presence of pre-existing debond, is found. A dislocation slip model is constructed in accordance with the shear mode. The mechanism of crystallographic slip is such that lateral thinning of the metal line at the debond region together with the slip step produced at the edges of debond lead to a net transport of atoms away from the debond area, and a physical void is thus formed. The significance and implications of this proposed micromechanism are discussed.