Nanocrystalline lead zirconate titanate (PZT) and lead lanthanum zirconate titanate (PLZT) have been synthesized in powder form by a single-step auto-ignition of metal–polymer gel precursor. The nanocrystalline powders were characterized using analytical transmission electron microscopy (TEM) equipped with an energy-dispersive x-ray spectrometer (EDXS) for composition analysis. For both PZT and PLZT, nanoparticles of sizes as low as 1–5 nm along with larger nanoparticles of sizes up to 30 nm are observed in the TEM. The selected-area diffraction (SAD) patterns from the nanoparticles revealed a face-centered cubic (fcc) crystal structure for both PZT and PLZT with a lattice parameter of ∼0.51 nm. The formation of PZT and PLZT nanoparticles of sizes below 5 nm with metastable fcc crystal structure has been observed for the first time. It is concluded that, as the crystal size decreases, the system assumes crystal structures of higher symmetry initially through small changes in lattice parameters and, in extreme cases, through chemical disorder for ultrafine nanoparticles.

Recently, we selected the antibody fragment with high affinity for the biopolymer film of polyhydroxybutyrate (PHB) from human antibody fragment libraries. In this study, we functionalized CdSe quantum dot (QD) nanoparticles by orderly conjugating the anti-PHB antibody fragments to perform spontaneous and selective stacking of inorganic particles on PHB-coated plates in neutral solutions at room temperature. Surface plasmon resonance analysis showed that the orderly clustering of anti-PHB antibody fragment on QD particles led to no dissociation of QD on PHB-coated plates, indicating the availability of avidity effect. The strong spontaneous immobilization using biomolecular recognition enabled stepwise stacking of inorganic particles on PHB-coated plates only by mixing operation in neutral solutions at room temperature. We show the potential of recombinant anti-material antibody fragments for the bottom-up stacking procedures for hybrid assembly.

Pure CdSe and Mg-doped CdSe nanocrystal quantum dots were synthesized into the zinc-blende structure at a low temperature by the inverse micelle technique using paraffin oil and oleic acid as surface capping agents. The ripening behavior of the nanocrystals was monitored using the red shift in ultraviolet (UV)-visible light absorption peaks, and their size variation was estimated using the so-called, quantum confinement theory. The Lifshitz–Slyozov–Wagner (LSW) kinetics analyses were performed based on the variation in size according to the ripening temperature and time period. The activation energy (Q) and reaction rate constant (Ko) were determined for the ripening reaction using Arrhenius-type plots. The kinetics analyses reveal that the volume diffusion through the liquid-phase solution is the governing mechanism for the ripening of both nanocrystals. The Mg-doped CdSe nanocrystals showed enhanced ripening kinetics due to the low activation energy for the volume diffusion.

Glass-forming ability (GFA) in relation to microstructure evolution in the ternary Fe–Nb–B and Fe–Zr–B and quaternary Fe–(Nb,Zr)–B systems was systematically studied in a three-dimensional composition space. Through navigating, it was revealed that alloys with the optimum glass-forming ability (GFA) are coupled with composition regions surrounded by competing crystalline phases. Alloys Fe71Nb6B23, Fe77Zr4B19, and Fe71(Nb0.8Zr0.2)6B23 were illustrated to be the best glass formers in the ternary Fe–Nb–B and Fe–Zr–B systems and the quaternary Fe–(Nb,Zr)–B system, respectively, with a critical size for amorphous formation up to 2 mm. They were compared with the theoretical predictions on the basis of an efficient dense-packing model, and good agreements were obtained.

Using an infrared camera, the temperature evolution of as-cast and relaxed bulk metallic glasses during compression was measured. Substantial variations in the temperatures of both glasses during plastic deformation were observed, which are conjectured to result at least partially from shear-banding phenomena. The relaxed glass has a larger temperature rise than the as-cast glass, which can be attributed to a reduction in the free volume. The larger temperature increase in the relaxed glass may be responsible for the observed work softening. The relaxed glass also has a higher maximum temperature than the as-cast, which can be attributed to a stronger strain-rate dependence of the temperature rise rate, and a shorter dissipation time scale for the heat due to conduction. The experimental data follow the well-known model behavior, and suggest the possibility of a statistical correlation between the fluctuations of strain rates and the rates of the temperature variation.

The porosity of electrophoretically prepared nanoporous ZnO and TiO2 films was systematically decreased by postpressing at different pressures. The nanoporous structure of the films was fixed by sintering after the postpressing procedure. The postpressing-induced change of the internal surface area of the nanoporous films was monitored using the dye-removal technique. The effective electron diffusion coefficient (Deff) of the unpressed nanoporous films depended on the thickness according to Fick’s second law. When pressed, the diffusion coefficient of the films increases significantly. In nanoporous TiO2, the increase of Deff follows the percolation theory where transport rate depends on the particle-coordination number. In contrast to the TiO2 films, the value of Deff of pressed nanoporous ZnO films changed with the porosity much stronger than one would expect from the percolation theory with hard spheres. This property has been attributed to the strong increase of necking between ZnO nanoparticles with increasing pressure as indicated by a strong decrease of the internal surface area.

Following Part I [X. Yao, et al., J. Mater. Res.23(5), 1282 (2008)] and Part II [X. Yao, et al., J. Mater. Res.23(5), 1292 (2008)] the cellular automation–finite control volume method (CAFVM) model was used to study the grain formation and microstructure morphology resulting from solidification of a commercial Al–Si–Mg alloy with Al–Ti–B grain refiner additions. The model incorporates the effect of the introduced solute Ti and the alloying elements of Si and Mg on the growth restriction factor, constitutional undercooling, and nucleation parameters. With respect to grain refinement, it is found that the alloying elements, Si and Mg, play a role that is similar to Ti qualitatively while different quantitatively. Accordingly, a concept of “equivalent solute” determined by phase diagram parameters such as the solute partitioning coefficient and the liquidus slope is proposed to clarify the effect of each solute in the alloy on grain formation during solidification. Based on the calculations and on comparison to the experimental data, a possible mechanism of grain refinement in this alloy system is proposed.

Despite the importance of the prior-β grain structure in determining the properties of titanium-based alloys, there are few published studies on methods of controlling the size of these grains in commercial alloys. The existing research raises questions about the relative importance of solute elements in grain-refining mechanisms, particularly the common alloying elements of aluminum and vanadium. The effect of these elements was investigated by producing a series of castings in a nonconsumable arc-melting furnace, and the results were interpreted with the aid of available phase-diagram information and solute-based models of grain refinement. A small reduction in grain size was obtained with increasing solute additions; however, this was not expected from the theoretical analysis. Possible reasons for this discrepancy are discussed.

The current study revealed the effects of strain rate on tensile strength and ductile-to-brittle transition of Sn–3Cu/Cu joints in the strain rate range of 4.2 × 10−5 to 2.4 × 10−1 s−1. Experimental results indicate that these joints broke in a ductile manner at low strain rates with a rapid increase in the tensile strength but displayed a brittle manner at higher strain rates with a slow increase in the tensile strength, indicating a typical ductile-to-brittle transition feature. A method was proposed to estimate the interfacial strength between the solder and the intermetallic compounds.

The photocatalytic degradation of methylene blue (MB) over a porous titania-hydroxyapatite (HAp) composite under ultraviolet radiation was studied. The catalyst was prepared by coating porous HAp with a titanium butoxide [Ti(OBu)4] sol at titania loadings of 17–49 wt%. Quantitative powder x-ray diffraction showed higher proportions of anatase as the calcination temperature increased from 500 to 800 °C due to crystallization of an amorphous precursor. The transformation of anatase to rutile was delayed until 900 °C, demonstrating the high thermal stability of the composite. Decomposition of HAp to α- and β- tricalcium phosphates takes place at 900 °C and is accompanied by the formation of perovskite at 1000 °C. A systematic study of the influence of calcination temperature and titania:HAp ratios demonstrated that for the optimal material, a surface area of 100 m2 g−1 was obtained at a titania loading of 49 wt% and calcination temperature of 600 °C. A highly dispersed suspension of finely ground titania-HAp enhanced the photodegradation of MB, allowed a high percentage recovery of catalyst, and was shown to be recyclable.

Crystalline tungsten suboxide nanowires were grown on silicon substrates by thermal evaporation of tungsten powder in a flow of argon gas without any catalyst. With different growth temperatures, two kinds of tungsten suboxide nanowires (W18O49 and W20O58) were obtained. The structures, morphologies, and compositions of these two nanowires were characterized by scanning electron microscopy (SEM), electron probe microanalyzer (EPMA), x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), x-ray photoelectron spectroscopy (XPS), and Raman techniques. The results show that XRD and TEM are not good characterization techniques for identifying W18O49 and W20O58 nanowires; however, Raman spectroscopy (RS) is a powerful tool to distinguish the difference between them. This is due to the notable molecular bond contributing to the vibrational frequency.

The phase equilibria and phase transformation of the body-centered cubic (bcc) phase in the Cu–Ti–Al system were investigated by the diffusion couple method, metallographic examination, differential scanning calorimetry, and x-ray diffraction. The isothermal sections at 700 and 900 °C and vertical sections at 18 at.% Al, 22 at.% Al, and 25 at.% Al in the Cu-rich portion were determined. These results indicate that (i) the Cu2TiAl compound with the L21 Heusler structure has a larger solubility range; (ii) the stable B2 + L21 miscibility gap of the ordered bcc phase exists until the liquid phase, and the tie lines of this miscibility gap are almost parallel with the Cu–Ti side; (iii) the composition and temperature for the eutectic reaction (L ↔ B2 + L21) are about 7 at.% Ti and about 970 °C, respectively, and (iv) the velocity of the eutectoid decomposition [bcc ↔ face-centered cubic (fcc) + D83] of the bcc phase with martensitic morphology in the Cu–Ti–Al alloys is slower than that of the Cu–Al alloys.

Nickel ferrite nanostructured particles coated with chemisorbed oleic acid were successfully synthesized by nonhydrolytic sol-gel method. By varying the composition of metal precursors, two microstructures were obtained, i.e., dispersed nanocrystals (9.7 ± 1.8 nm) and submicron aggregates (152 ± 21 nm) consisted of many nanocrystals (8.1 ± 1.3 nm). Because oleic acid could form complex with iron (III) ions, but not with nickel (II), increasing the concentration of iron precursor consumed more oleic acid and led to insufficient oleic acid coating on particle surface. Strong intercrystallite interaction was induced from less protected nanocrystals, and aggregation thus occurred between different crystallites.

Polyvinylidene difluoride fibers and composite fibers with Ni–Zn ferrite nanoparticles and rutile nanoparticles were prepared by electrospinning dimethyl formamide (DMF) solutions. To prevent agglomeration, the ferrite nanoparticles were coated with silica, allowing the formation of a stable ferrofluid in DMF as well as the formation of homogeneous fibers. The rutile nanoparticles could be spun with a uniform distribution within the fiber without silica coating. The effects of various solution properties (viscosity and solids loading for composite fibers) and processing parameters (flow rate and voltage) on fiber morphology and diameter were studied to identify a processing window that resulted in the formation of smooth, defect-free fibers. Of the variables examined, fiber diameter was found to be the most strongly dependent on the viscosity of the electrospinning solution. Infrared spectroscopy revealed that the inclusion of well-dispersed nanoparticles in the electrospun fibers enhanced the presence of the ferroelectric phase in the composite fibers.

Three-point bend test coupled with transmission electron microscopy (TEM) analysis was carried out on individual tungsten oxide nanowires (NWs) before and after annealing. Three-point bend test monitors the change in the Young’s modulus of the NW after annealing, while TEM provides nanostructural detail changes on the same NW. In this way, insight into the correlation between the mechanical properties of a NW and its nanostructure details can be obtained. Annealing increased the diameter of the NWs by forming a uniform amorphous/polycrystalline outer coating. The coating results in a decrease in Young’s moduli for thicker NWs. On the other hand, annealing led to increased Young’s moduli of thinner NWs, which is attributed to the improved crystallinity in these NWs after annealing. This study points to a more refined strategy for more in-depth understanding of the relationship between the nanostructures and elastic mechanical properties of NWs.

BioSiC is a biomimetic SiC-based ceramic material fabricated by Si melt infiltration of carbon preforms obtained from wood. The microstructure of bioSiC mimics that of the wood precursor, which can be chosen for tailored properties. When the remaining, unreacted Si is removed, a SiC material with interconnected porosity is obtained. This porous bioSiC is under study for its use as a medical implant material. We have successfully fabricated bioSiC from Sipo wood and studied the kinetics of Si removal by wet etching. The results suggest that the reaction is diffusion-limited, and the etch rate follows a t−0.5 law. The etching rate is found to be anisotropic, which can be explained attending to the anisotropy of the pore distribution. The compressive strength was studied as a function of etching time, and the results show a quadratic dependence with density. In the attainable range of densities, the strength is similar or better than that of human bone.

Indentation techniques are used for the measurement of mechanical properties of a wide range of materials. Typical elastic analysis for spherical indentation is applicable in the absence of time-dependent deformation, but is inappropriate for materials with time-dependent creep responses active in the experimental time frame. In the current work, a poroelastic analysis—a mechanical theory incorporating fluid motion through a porous elastic network—is used to examine spherical indentation creep responses of hydrated biological materials. Existing analytical and finite element solutions for the poroelastic Hertzian indentation problem are reviewed, and a poroelastic parameter identification scheme is developed. Experimental data from nanoindentation of hydrated bone immersed in water and polar solvents (ethanol, methanol, acetone) are examined within the poroelastic framework. Immersion of bone in polar solvents with decreasing polarity results in increased stiffness, decreased Poisson’s ratio, and decreased hydraulic permeability. Nanoindentation poroelastic analysis results are compared with existing literature for bone poroelasticity at larger length scales, and the effective pore size probed in indentation creep experiments was estimated to be 1.6 nm, consistent with the scale of fundamental collagen–apatite interactions. Results for water permeability in bone were compared with studies of water diffusion through fully dense bone.

A method to fabricate continuous and aligned multiwalled carbon nanotube (CNT)/epoxy composites is presented in this paper. CNT/epoxy composites were made by infiltrating an epoxy resin into a stack of continuous and aligned multiwalled CNT sheets that were drawn from super-aligned CNT arrays. By controlling the amount and alignment of the continuous multiwalled CNT sheets, a CNT/epoxy composite with high content of well-dispersed CNTs can be obtained. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) results show that the thermal stability of these CNT/epoxy composites was not affected by the addition of CNTs. The mechanical properties and electrical properties of the CNT/epoxy composites were dramatically improved compared to pure epoxy, suggesting that the CNT/epoxy composites can serve as multifunctional materials with combined mechanical and physical properties.

Ultrahard boron nitride compacts containing nanosized domains of the cubic (c-BN), wurtzitic (w-BN), and hexagonal (h-BN) phase were synthesized at high-pressure/high-temperature (HP/HT) conditions. Hot-pressed and pyrolytic BN, both containing h-BN as a main component, were used as starting materials. The HP/HT products were investigated by x-ray diffraction via Rietveld and line-profile analysis, as well as high-resolution transmission electron microscopy. c-BN was the dominant phase in all products, complemented by up to 25 wt% w-BN and some remaining “compressed h-BN.” In particular samples, partial crystallographic coherence of adjacent crystallites to x-rays was observed, which has been previously found in superhard transition metal nitride-based nanocomposite coatings. In the BN nanocomposites, the partial coherence of nanocrystallites to x-rays was improved by their strong local preferred orientation, which is made possible by the well-known orientation relationships among h-BN, w-BN, and c-BN phases. The correlation between the weight fraction and the average size of the c-BN crystallites helped to describe the formation of c-BN/(w-BN) nanocomposites from submicron-sized h-BN domains in the starting materials. The Knoop and Vickers hardness of specimens with crystallite sizes ranging from 6 to ∼50 nm was found to be significantly higher than that of c-BN single crystals, despite the presence of residual h-BN.

Dimensional analysis is used to show that the maximum penetration depth and the tip radius affect the β correction factor appearing in the Sneddon relationship between unloading contact stiffness, contact area, and elastic modulus. A simple analytical model based on elasticity theory is derived that predicts the variation of β with penetration depth. This model shows that β increases at low penetration depth and decreases with the tip radius. The β(h) curve given by the model is compared with that calculated by finite element analysis for an elastic material and also with that deduced from experimental measurements performed on fused quartz with two Berkovich indenters: a sharp one and a blunted one. It is also demonstrated that the correction factor can be expressed as two multiplicative contributions, a contribution related to the mechanical properties of the material and a contribution related to the indenter geometry. Implications of these findings on nanoindentation test are also discussed.