We described previously the liquid phase synthesis and characterization of a nanostructured composite from an aqueous solution containing organic polymer and inorganic ions [J. Mater. Res. 7, 2599 (1992)]. The nanocomposite, termed an organoceramic, consisted of poly(vinyl alcohol) chains intercalated between the principal layers of a hydrated calcium aluminate ceramic. A key structural feature of the organoceramic is the polymer-induced expansion of the interlayer spacing by approximately 10 Å compared to the unmodified ceramic. In this paper, we describe the synthetic scheme that favors organoceramic formation and prove the existence of intercalated polymer by observation of reversible interlayer expansion and contraction in response to changes in ambient humidity. This property is unique to the organoceramic and is not observed in the unmodified calcium aluminate ceramic.

The roughness of metallic surfaces generated by machining depends on the intended intervention by the tool and the inadvertent consequences determined by the response of metals. The roughness generated in four different metals by grinding is studied using the power spectrum method. It was found that the level of power is determined by the intended intervention such as the depth of cut and, to some extent, by hardness because of its possible influence on micropileup geometry. The power gradient is, however, influenced by inadvertent damage which may be related to material properties such as thermal conductivity and adhesion.

Stability of fullerenes C60 under hydrothermal conditions (200–800 °C, 100 MPa, 20 min–168 h) has been investigated. The reaction products have been characterized by Raman spectroscopy and x-ray diffraction. The fullerenes were stable up to 500 °C, but they decomposed immediately at 800 ±C into amorphous carbon. In the transition region between 600 and 750 °C, longer times and higher temperatures of the hydrothermal treatment favored decomposition of C60 with the formation of amorphous carbon. Addition of nickel to the C60–H2OO system neither suppressed hydrothermal decomposition of C60 nor induced formation of other phases, except of the amorphous carbon.

Alkyl phosphates can be used as sol-gel precursors for phosphate-based glasses and glass-ceramics. An improvement in the synthesis of alkyl phosphates is presented. Following the procedure here described, it is possible to limit the fraction of condensed phosphates to 1–2%. At the same time, a ratio between mono- and di-substituted phosphates near to that given by the reaction stoichiometry may be attained.

The third-order optical nonlinearity of glasses of the Na2S–PbS–GeS2 and Na2S–PbO–GeS2 systems was measured by third-harmonic generation method. The third-order nonlinearities of glasses of both systems increase with the increasing lead content. The maximum value of the third-order optical nonlinearity was 3.00 × 10-12 esu. The addition of PbO basically has little influence on third-order optical nonlinearity, and the largest nonlinearity is 1.49 × 10-12 esu. The minimum appearing at 15 mol% PbO can be explained by the decrease of number density of lead and sulfur. Chemical durability of oxysulfide glasses is superior to that of a pure sulfide system; thus the addition of PbO is important in this sense.

Two new compounds, GdBa4Cu3O8.5+δ (Gd143) and DyBa4Cu3O8.5+δ (Dy143), were synthesized from precursors Gd2O3, Dy2O3, BaO2, and CuO at 1000 °C in an oxygen atmosphere. The oxygen stoichiometric value δ was found to be 0.68 for Gd143 and 0.6 for Dy143 by iodometric titration. Rietveld refinement of x-ray powder diffraction data showed that Gd143 belongs to the space group Pm3 while Dy143 belongs to the space group P23. The two space groups, Pm3 and P23, are very similar. Their main difference is that P23 does not have the inversion symmetry of Pm3. Both compounds have a cubic unit cell with a lattice parameter of 8.16528 ± 0.00006 Å for Gd143 and 8.10807 ± 0.00010 Å for Dy143. Superconducting quantum interference device (SQUID) measurement indicated that neither compound was superconductive down to 5 K.

We studied the effect of lead content (x = 0.20−0.40) on the critical current density Jc (0 T, 77 K), irreversibility field H* (77 K), and microstructure of monocore, Ag-clad Bi1.8PbxSr2Ca2Cu3Oy (2223) tapes, finding that tapes with lower lead contents (x = 0.20–0.25) required higher processing temperatures (840 and 832 °C, respectively) to complete 2223 formation, as compared to the optimum 820 °C reaction temperature of the x = 0.30–0.40 tapes. We found that both the zero-field and the in-field properties correlated strongly to the phase purity with Jc (0 T, 77 K) reaching a maximum of ˜20 kA/cm2 for x = 0.30, and then decreasing with increasing lead content to ˜12 kA/cm2 for x = 0.40. H* (77 K) increased from ˜165 mT at x = 0.20 to ˜265 mT at x = 0.30, then declined to 195 mT at x = 0.40. Optimizing the lead content at x = 0.30 maximized both the connectivity and the flux pinning contributions to the critical current density.

We investigated the relationship between the structure and misorientation angle of (001) twist grain boundaries in Bi2Sr2Ca1Cu2Oy/Ag composite tapes processed in different oxygen partial pressures (PO2 = 0.01, 0.21, and 1 atm). Large-angle misoriented twist boundaries (>10°) essentially had no amorphous layers at the interface, and the misorientation angles of these boundaries mostly corresponded to low-energy misorientations. This large-angle misoriented boundary structure was independent of PO2. Small-angle misoriented twist boundaries (<10°), on the other hand, corresponded to high-energy misorientations and sometimes had amorphous layers at the interface. The population of the small-angle boundary with an amorphous layer was very low in the tape processed in PO2 = 1 atm. This suggests that high PO2 during the heat treatment is effective in the improvement of grain coupling, and hence, to increase critical current density.

The deformation behavior of melt-textured Y1Ba2Cu3O7-x (YBCO) prepared by the vertical gradient freeze (VGF) method was investigated by high temperature deformation experiments at temperatures ranging from 850 to 950 °C. The experiments were performed in an atmosphere of pure oxygen under uniaxial pressure with constant strain rates in the range from 1 × 10−5 to 5 − 10−4 s−1. An analysis of the dependence of the steady state flow stress on the strain rate and the deformation temperature reveals that the predominant deformation mechanism is dislocation glide and climb controlled by climb at Y-211 particles and that no significant grain boundary sliding occurs. Furthermore, transmission electron microscopy observations of deformed and undeformed samples support a deformation mechanism based on dislocation movement. The total fracture strain, however, does not depend on the temperature or strain rate. Scanning electron microscopy investigations of the fracture faces of samples deformed until fracture reveal that fracture does not occur within the Y-123 matrix but along platelet boundaries. An improvement of the fracture behavior is expected by introducing large Y-211 particles interconnecting neighboring platelets.

The size distributions of Si and ZnTe nanoparticles produced by low energy density ArF (193 nm) pulsed laser ablation into ambient gases were measured as a function of the gas pressure, P, and target-substrate separation, Dts. For both Si and ZnTe, the largest nanoparticles were found closest to the ablation target, and the mean nanoparticle size decreased with increasing Dts. For Si ablation into He, the mean nanoparticle diameter did not increase monotonically with gas pressure but reached a maximum near P = 6 Torr. High resolution Z-contrast transmission electron microscopy and energy loss spectroscopy revealed that ZnTe nanoparticles consist of a crystalline core surrounded by an amorphous ZnO shell; growth defects and surface steps are clearly visible in the crystalline core. A pronounced narrowing of the ZnTe nanocrystal size distribution with increasing Dts also was found. The results demonstrate that the size of laser-ablated nanoparticles can be controlled by varying the molecular weight and pressure of an ambient gas and that nanometer-scale particles can be synthesized. Larger aggregates of both ZnTe and Si having a “flakelike” or “weblike” structure were formed at the higher ambient gas pressures; for ZnTe these appear to be open agglomerates of much smaller (∼10 nm) particles.

A systematic investigation has been made on surface defect states of crystallites in the crystallization process of sputtered amorphous silicon films by isothermal annealing. Transmission electron microscopic observations indicate a pronounced vertical columnar structure in the upper part of the films, where the crystallization is delayed. Admittance spectroscopy reveals that two newly generated energy levels with the crystallization are attributed to the crystallites in the lower and upper parts of the films in view of the anisotropic crystallization. These thermally induced changes can be well explained by Si–Si shearing modes at the interfaces of crystallites through the process of crystallization.

Formation of a homogeneous nanocrystalline CuIn0.7Ga0.3Se2 alloy was achieved by mechanical alloying of blended elemental Cu, In, Ga, and Se powders in a planetary ball mill. X-ray diffraction and transmission electron microscopy and diffraction techniques were employed to follow the structural evolution during milling. It was observed that, depending upon the milling conditions, either a metastable cubic or a stable tetragonal phase was produced. The grain size of the mechanically alloyed powder was about 10 nm. The mechanically alloyed powder was consolidated to full density by hot isostatic pressing the powder at 750 °C and 100 MPa for 2 h. Irrespective of the nature of the phase in the starting powder, the hot isostatically pressed compact contained the well-recrystallized tetragonal CuIn0.7Ga0.3Se2 phase with a grain size of about 50 nm.

The precipitation behavior of various phases during the aging process of an Ag–Li°Cu–Mg–Zr–Ag (Weldalite 049) alloy was investigated by high-resolution electron microscopy and in situ hot-stage microscopy. Two kinds of domains with L12-type ordered structures, which are considered to be δ′ and β′ phases, are observed with different domain sizes in the alloy quenched from 530 °C. In the early stage of aging at 190 °C, the δ′ phase is precipitated as surrounding the β' phase, and the δ′ domains appear with in-phase and antiphase relationships to the β′ lattices. In situ observations at 190 °C clearly show that the T1 phase precipitates predominantly on dislocations at subgrain boundaries and then is homogeneously formed in the matrix with increasing aging time. The nucleation of the S′ phase is associated with clustering of Cu and Mg in the matrix, and the S0 domains are grown with {210} habit planes.

The precipitates in nitrogen-added type 316L stainless steels (SS) were investigated by transmission electron microscopy (TEM) after thermal aging. Besides carbides (M23C6 and M6C) and intermetallic phases, an unknown phase of an Fe–Mo–Cr(–Si) system n a filmlike morphology precipitated at grain boundaries. In spite of the similarity in ts chemical composition to that of the Laves phase, the phase of the Fe–Mo–Cr(–Si) system exhibited five-, three-, and twofold symmetries, which are generally observed in quasicrystals having icosahedral symmetry. This phase was formed from the intergrowth of small crystalline clusters of the Laves phase. Decreasing the nitrogen content to that of commercial type 316L grade suppressed the formation of the filmlike fivefold phase. This was attributed to the dissipation of small Laves clusters by M23C6 carbides, which increased as a result of the decreased nitrogen content.

Ultrafine Fe, Fe–Ni, and Ni particles were prepared by using the hydrogen plasma-metal reaction method in a mixture of H2 and Ar of 0.1 MPa. The particles were characterized by x-ray diffraction, transmission electron spectroscopy, energy disperse spectroscopy, chemical analysis, and Mössbauer spectroscopy. In contrast with bulk Fe–Ni alloys, the distinguishing features in corresponding ultrafine particles are that two phases with fcc and bcc structures coexist in a wide composition range. Ultrafine Fe–Ni particles have higher resistance to oxidation than Fe and Ni particles. The mechanism of forming particles was analyzed by means of structural and magnetic measurements. It was found that quenching is a dominant mechanism for forming paramagnetic particles. Hyperfine interactions were studied by Mössbauer spectroscopy in comparison with those in bulk Fe–Ni alloys.

We investigate the effects of layer thickness (t) on hardness (H) and rate sensitivity of the hardness (∂H/∂ ln ) in 1 μm-thick Cu/Nb nanolayer composites. For t < 10 nm, we find that H correlates with t according to H = H0 = H1t-1/2, suggestive of a Hall–Petch mechanism with layer interfaces replacing grain boundaries as barriers against dislocation motion. The measured levels of ∂H/∂ ln clearly indicate the operation of bulk-like dislocation mechanisms consistent with a Hall–Petch mechanism. However, based on a Haasen-plot activation analysis, it appears that the Hall–Petch coefficient, H1, is strongly rate-dependent, inconsistent with a conventional Hall–Petch mechanism. For specimens with t < 10 nm there is a saturation in hardness, but the rate sensitivity data indicate no clear evidence of a corresponding change in mechanism. Simple models are proposed.

Novel biomaterials for application to artificial bone with modulus of elasticity close to that of natural bone were prepared using bioresorbable poly-L-lactic acid (PLLA) and high-strength β–Ca(PO3)2 fibers treated with dilute NaOH solution. PLLA dissolved by using methylene chloride was mixed with the fibers. After drying the mixture, it was hot-pressed uniaxially under a pressure of 40 MPa at 180 °C, resulting in fabrication of a PLLA composite containing β–Ca(PO3)2 fibers. Almost no degradation in the bending strength was observed even when a large amount of the fibers (≈50 wt. %) was introduced, and the modulus of elasticity was increased effectively with increasing the fiber content. The PLLA composite with modulus of elasticity of <5 GPa similar to that of natural bone was found to be prepared when the fiber content was over 35 wt. %. The bending test of the composites showed that very high energy is consumed for their fracture and that the fracture proceeds step by step, even beyond the maximum stress.

The feasibility of the acetylacetonate-Ti isopropoxide complex as a new precursor for synthesis of Ti-based perovskite particles under hydrothermal conditions has been demonstrated. Perovskite powders including BaTiO3, PbTiO3, PZT, PLZT, and SrTiO3 were prepared by reacting the acetylacetonate-modified Ti precursor in metal acetate aqueous salt solution under hydrothermal conditions. Synthesis parameters including reaction time and temperature, feedstock concentration, nd reaction medium significantly influence particle characteristics of the hydrothermally derived erovskite powders. It is proposed that use of the acetylacetonate-modified Ti precursor promotes ntimate mixing among multicomponent reacting species at the molecular level and promotes article formation through a dissolution/recrystallization mechanism.

In situ and ex situ spectroscopic ellipsometry (SE), Raman spectroscopy (RS), x-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES) have been used to study the stoichiometry and characterize TiNx thin films deposited by magnetron sputtering at various stoichiometries. In situ SE can provide parameters, such as the plasma energy, that can be utilized for monitoring of the film stoichiometry. Besides plasma energy, optical phonon position in RS was also found to be a sensitive probe of TiNx stoichiometry as detected by RS, XPS, and ex situ SE. Under these conditions, AES faces difficulties for reliable film characterization, and the complementary use of other techniques is required for determining the exact film stoichiometry.

Four samples of TiO2 ultrafine particles (UFP) were obtained through different processes. The structure of TiO2 ultrafine particles and the factors influencing the structure were investigated with Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and x-ray diffraction (XRD). Both Raman spectra and x-ray diffractograms show the similar regularity of the phase transformation among the four samples. The observed bimodal lineshape-structure in the Raman spectra is attributed to the intragrain and grain-boundary components of TiO2 UFP. The crystal structure of TiO2 UFP is found to be distorted by the surface structure such as OH and OCH2CH3 groups coordinated on the surface of TiO2 UFP.