The kinetics and microstructure of solid-phase crystallization under continuous heating conditions and random distribution of nuclei are analyzed. An Arrhenius temperature dependence is assumed for both nucleation and growth rates. Under these circumstances, the system has a scaling law such that the behavior of the scaled system is independent of the heating rate. Hence, the kinetics and microstructure obtained at different heating rates differ only in time and length scaling factors. Concerning the kinetics, it is shown that the extended volume evolves with time according to αex = [exp(κCt′)]m+1, where t′ is the dimensionless time. This scaled solution not only represents a significant simplification of the system description, it also provides new tools for its analysis. For instance, it has been possible to find an analytical dependence of the final average grain size on kinetic parameters. Concerning the microstructure, the existence of a length scaling factor has allowed the grain-size distribution to be numerically calculated as a function of the kinetic parameters.

A simple thermal annealing was performed to prepare tungsten oxide nanorods directly from tungsten (W) film. The W film was deposited on Si(100) substrate by chemical vapor deposition (CVD) at 450 °C using W(CO)6. A high density of tungsten oxide nanorods was produced by heating of the W film at 600–700 °C. The morphology, structure, composition, and chemical binding states of the prepared nanorods were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) analysis. XRD and TEM results showed that the grown nanorods were single-crystalline W18O49. According to XPS analysis, the W18O49 nanorods contained ∼55.69% W6+, ∼32.28% W5+, and ∼12.03% W4+. The growth mechanism based on thermodynamics is discussed for the growth of tungsten oxide nanorods from W film.

Silicon nanoporous pillar array (Si-NPA) is a silicon hierarchical structure with regularly patterned surface morphology. Through a heterogeneous reaction process, zinc sulfide nanocrystallites (nc-ZnS) were grown onto Si-NPA and a unique heterostructure of ZnS/Si-NPA was obtained. The formation of wurtzite nc-ZnS was proved by x-ray diffraction, and the average grain size was evaluated to be ∼18 nm. X-ray photoelectron spectroscopy disclosed that as-grown nc-ZnS was well separated from Si-NPA by a SiO2 thin layer of ∼1.3 nm. The photoluminescence (PL) spectrum of ZnS/Si-NPA showed that in addition to the two red PL bands peaked at ∼648 and ∼705 nm observed in Si-NPA, three other PL bands peaked at ∼365, ∼418, and ∼472 nm were observed and attributed to the PL from nc-ZnS. It was also demonstrated that as-prepared ZnS/Si-NPA heterostructure could exhibit good rectification characteristic featured by a high forward current density of ∼75 mA/cm2 at 2 V and high reverse breakdown voltage of ∼10 V. Our results indicated that ZnS/Si-NPA might be a valuable heterostructure nanosystem to be further probed for achieving enhanced optical and electrical properties.

The oxidation behavior of three types of plasma-enhanced chemical vapor deposition (PECVD) processed Ti–Si–C–N coatings with silicon content ranging from 4.3 to 11.6 at.% has been investigated at high temperatures. Systematic characterization was conducted to study the evolution of composition, phase constituents, hardness, surface morphologies, microstructures, and grain size during oxidation. A two-stage oxidation process was observed between 700 and 1000 °C for all three coatings. Experimental results indicate that a superhardness of 40 GPa can be maintained up to 700, 800, and 850 °C for 4.3, 7.4, and 11.6 at.% Si coatings, respectively; the dual-phased 7.4 and 11.6 at.% Si coatings show a better oxidation resistance than the single-phased 4.3 at.% Si coating. On the basis of the results, a mechanism is proposed to explain the relationship between the nanostructure and oxidation behavior.

Advanced microelectronic interconnection structures will need dielectrics of low permittivity to reduce capacitive delays and crosstalk, but this reduction in permittivity typically necessitates an increase in the porosity of the material, which is frequently accompanied by reduced mechanical reliability. Failure by brittle fracture remains a typical manufacturing and reliability hurdle for this class of materials. Part I of this two-part work explores the instrumented indentation and indentation fracture responses of a variety of organosilicate low-dielectric constant (low-κ) films. Three different chemical varieties of low-κ material were tested. The influence of film thickness on the fracture response is also explored systematically. Correlations are made between instrumented indentation responses and differing modes of fracture. It is demonstrated that the elastic response of the composite film + substrate systems can be simply tied to the fraction of the total indentation strain energy in the film. These results are then used in the companion paper, Part II [D.J. Morris and R.F. Cook, J. Mater. Res.23, 2443 (2008)], to derive and use a fracture mechanics model to measure fracture properties of low-κ films.

We have investigated structural changes of amorphous borosilicon carbonitride materials with atomic ratios of B/Si/C of 2/3/6 and 4/3/6 calcined at several temperatures. The boron K-edge x-ray absorption spectra showed that the structures of both hexagonal boron nitride ([BN3] unit) with nitrogen-void defects ([BN2] and [BN1] units) and boron oxide existed in the samples, and the relative peak intensity due to the [BN3] unit became stronger by increasing the calcined temperature. It is thought that the well-developed B–N chain and the borosilicate glass coating lead to the high resistance to oxidation at high temperature. X-ray diffraction and infrared measurements followed the x-ray absorption near-edge spectroscopy findings.

Nanocrystalline SrTiO3 particle/polymer composite film was synthesized from a titanium–organic film and strontium ion in aqueous solution by applying a direct current (dc) field. The titanium–organic precursor was synthesized from acetylacetone-modified titanium isopropoxide and a methacrylate derivative. Ultraviolet treatment of the titanium–organic film decreased the leaching of Ti moieties from the precursor film during dc treatment. Crystalline SrTiO3 particles were formed in the precursor films on stainless-steel substrates under a dc field above 40 °C without a high-temperature process. The size of SrTiO3 particles increased with increasing reaction temperature from 40 to 50 °C at 3.0 V/cm. SrTiO3 particles also increased in size with increasing reaction time from 35 to 60 min at 3.0 V/cm and at 50 °C. SrTiO3 particle/polymer films were synthesized on stainless-steel substrates at 3.0 V/cm and 50 °C for 60 min.

We have investigated the polarity of zinc oxide (ZnO) and Al-doped ZnO films grown on (11¯20) and (0001) sapphire substrates, using coaxial impact collision ion scattering spectroscopy. The films grown by pulsed laser deposition with a nominally undoped ZnO ceramic target had a (000¯1) surface, whereas the films prepared with a 1 mol% Al-doped ZnO ceramic target had a (0001) surface. The usage of Al-doped and undoped targets caused no difference in the in-plane lattice orientation. Electron microscope observations revealed that polarity change due to doping occurred without the formation of any interfacial phase between ZnO and sapphire.

Amorphous Ti66Nb13Cu8Ni6.8Al6.2 alloy powders with different tungsten carbide (WC) contents were synthesized by mechanical alloying. Outstanding differences in particle size, thermal stability, glass-forming ability, and phase evolution are found for the synthesized Ti-based glassy powders with different WC contents. This is attributed to the fact that the WC was partially alloyed into the glassy matrix and the matrix element Ti was also partially alloyed into the WC particles. The obtained glassy powders exhibit a wide supercooled liquid region above 64 K. Meanwhile, the main crystalline phase is the ductile β-Ti with a high volume fraction in the crystallized alloy powders. These two aspects offer the possibility of easily preparing a plasticity-enhanced bulk composite in the supercooled liquid region by powder metallurgy, which couples the nanosized WC particles with in situ precipitated ductile β-Ti phase.

Nanostructured carbon materials, including carbon nanotubes, nanofibers, and nanowalls, exhibit a wide range of interesting properties dictated by the many different bonding configurations. Many of these materials can possess superhydrophobic behavior when water drops are placed on their surfaces: these drops have high contact angles and can roll freely on the surfaces, which is desirable for self-cleaning. In this work, we prepared porous carbon films using a microwave plasma enhanced chemical vapor deposition technique. These films showed superhydrophobicity with contact angle of 150°, which was explained by the synergetic effect of the highly rough surface combined with the hydrogen terminated edges of graphene sheets. However, the condensed water drops can behave differently: the drops did not roll readily. This behavior mimicked that of water on lotus leaves and further demonstrated that the reported superhydrophobic behavior is a function of how the water gets on to the surfaces.

The desorption–recombination behavior of a mechanically disproportionated, nanostructured Nd12Fe82B6 alloy was investigated by differential scanning calorimetry and thermogravimetric analysis. The microstructure change due to desorption–recombination treatments at various temperatures was characterized by x-ray diffraction, Mössbauer study, and transmission electron microscopy observation. The results show that the hydrogen desorption of the as-disproportionated alloy occurs in two stages: (i) the partial dehydriding of the Nd hydride from Nd2H5 to NdH2, as well as the desorption of the hydrogen absorbed/adsorbed at sites of crystal defects but not in the form of Nd hydride, at temperatures between 180 and 460 °C; and (ii) the complete dehydriding of the Nd hydride from NdH2 to Nd at temperatures between 630 and 780 °C. The recombination of α-Fe with Fe2B and Nd to form Nd2Fe14B occurs following the dehydriding of NdH2 to Nd, and it acts as the controlling step for the whole desorption–recombination process. The kinetics of both the desorption–recombination reaction and the growth of the newly formed Nd2Fe14B grains accelerate with increasing temperature. For a fixed annealing time of 30 min, the optimal processing temperature seems to be 760 °C, which gives rise to a fully recombined Nd2Fe14B–α-Fe nanocomposite microstructure with Nd2Fe14B and α-Fe phases of 25–30 nm in average size.

Micro texturing of titanium implant surfaces is commonly used to enhance fixation by osseointegration, and devising robust and specific correlations between surface topographic features and implant performance is an area of active current research. In this context, we present a detailed analysis of the topographies of titanium surfaces prepared by grit blasting (GB) and grit blasting followed by acid etching (GB+AE) at two different imaging scales over a full range of statistical parameters. The surfaces were characterized using white light interferometry and atomic force microscopy, and the topographic images were processed to extract the amplitude, spatial, hybrid, and functional parameters of the surface. Although GB+AE surfaces are known to elicit significantly higher bone response than GB surfaces, the topographies differed by less than 20% (over all parameters) when averaged over 242 × 181 μm interferometric images. In contrast, measurements over smaller 25 × 25 μm areas obtained using high-resolution atomic force microscopy indicated that the GB+AE surfaces exhibit a 26% increase in root-mean-square (rms) roughness, a 63% increase in rms slope, a 75% increase in the curvature of the summits, and a 21% increase in surface area over GB surfaces. These results constitute the first identification of rms slope and summit curvatures as important topographic variables that must be considered in ongoing efforts to correlate surface topography with the performance of endosseous titanium implants.

Dopamine covalently chelated ZnO nanoparticles were synthesized by a nonaqueous one-step chemical process at a temperature as low as 60 °C. The formation of ZnO/dopamine hybrid structure was proved by x-ray powder diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) techniques. Detailed absorption, luminescence, and time-resolved decay studies were performed for these ZnO/dopamine hybrid nanoparticles. We observed an enhanced green emission, which could be assigned to a new band-gap emission based on the fast of nanosecond lifetime of the green emission. Our results demonstrated that the change of optical properties of ZnO nanoparticles after covalently chelated by dopamine ligands is closely associated with the formation of new band structure.

The effects of TiO2 addition on the reaction behavior, product, and mechanism in the Ti–B4C system were investigated in this study. The reaction could be self-sustaining for the TiO2 addition no more than ∼33% of the total weight of the reactants. With an increase in the TiO2 addition, the combustion temperature and wave velocity decrease progressively, the ignition delay time first decreases and then increases, while the constituents of the reaction products do not vary significantly unless the relative addition content of TiO2 exceeds ∼22 wt%. Therefore, TiO2 could be used as a favorable reaction regulator for the Ti–B4C system. The reaction mechanism, as determined by differential thermal analysis and combustion front quenching experiment in combination with subsequent x-ray diffraction examination, is changed more or less by the addition of TiO2 with the extent depending on the addition amount.

Using classical molecular dynamics simulations, we have investigated the growth of {111} Cu on Nb {110} surface. Our results reveal that the deposited Cu layer initially grows as body-centered cubic (bcc) and Vernier misfits are observed in the interface of bcc Cu and bcc Nb. As it continues to grow, the bcc Cu {110} transforms into face-centered cubic (fcc) Cu {111}. The phase transition starts after the bcc Cu layer has accumulated about 3 monolayers and is finished depending on deposition parameters. Nuclei of fcc Cu {111} form in the top surface of Cu and grow in plane and toward the interface. Partial dislocations in the fcc Cu layer nucleate during the late stage of the transition, and the stacking faults grow as the Cu layer thickens.

The formation of metastable phases from an undercooled LuFeO3 melt was investigated under reduced Po2 since the iron ion has the tendency to change its valence state from Fe3+ to Fe2+ in an ambient atmosphere with low Po2. The nucleation and the post-recalescence temperatures of the phases were decreased with decreasing process Po2. Phase equilibrium was established in the Lu–Fe–O system at 1473 K by varying the oxygen partial pressure from 105 to 10−1 Pa. A possible ternary metastable phase diagram depending on the oxygen composition in the bulk sample was also constructed. The formation of the LuFe2O4 phase where the Fe3+ and Fe2+ ratio is 1:1 clearly indicated that the formation of metastable phases is related to the presence of Fe2+ ions. Thermogravimetric analysis revealed that the increase in sample mass with decreasing process Po2, down to 10−1 Pa, is relatively dependent on the amount of Fe2+ ions.

The room temperature deformation behavior of a LiNbO3 single crystal loaded along [0001] was studied by spherical nanoindentation. The threefold symmetry of the indentation marks was attributed to the formation of (10¯12) twins that reorient the basal planes to allow for basal slip, which is manifested by the formation of fully reversible, hysteretic loops upon cyclic loading. The differences in energy dissipation, threshold stresses, and loop shapes for the three different radii tips are attributed to the different sized twins that form. The results are consistent with our model for the formation of incipient kink bands within the twins.

Results on mechanical alloying of binary and ternary Mg–Ti-based mixtures are reported. Using fine-powdered reactants and a process-control-agent, a mixture of two face-centered cubic compounds is obtained. Using a coarse Mg precursor without addition of a milling agent results in a hexagonal-solid solution of Ti in Mg due to a lower oxygen content in the Mg starting material. Upon introduction of Ni or Al as a third element, the amount of dissolved Ti decreases to form a nanocrystalline secondary phase. The electrochemical charging capacity of the hexagonal compounds is far superior to that of the cubic ones, whereas the discharge capacity is significantly increased only upon addition of Ni. The secondary TiNi phase acts as a rapid diffusion path for hydrogen, greatly improving the rate capability of the alloys. The reversible hydrogen storage capacity reaches values of up to 3.2 wt% at room temperature for (Mg0.75Ti0.25)0.90Ni0.10.

Influence of casting temperature on the thermal stability of Cu- and Zr-based metallic glasses (MGs) was analyzed based on the monomer-cluster structural model using the Johnson–Mehl–Avrami (JMA) equation. The result indicates that increasing the casting temperature can enhance the thermal stability of MGs. It is suggested that it be attributed to the decrease in the amount of the local ordering clusters induced by the elevating casting temperature. The prediction is confirmed by continuous heating transformation diagrams constructed for the Cu- and Zr-amorphous samples obtained under different casting temperatures.

A thorough study of the selective wet oxidation in digital AlxGa1–xAs alloys is presented. We report experimental results and physical interpretation on the oxidation kinetics within those ranges of the AlGaAs composition (x = 0.95 to 1) and layer thickness (20 to 50 nm) of interest for oxide-aperture vertical-cavity surface-emitting laser (VCSEL) application. We demonstrate the high controllability of the oxidation reaction between different Al compositions; made different thanks to the use of digital alloys. Unlike standard alloys, we measured an invariability of the oxidation rates in the studied thickness range (20–50 nm), implying a better control of the fabrication process. The dependence of the reaction rate with the temperature is expressed as an Arrhenius law. Two activation energies (1.2 and 0.55 eV) have been derived for composition ranges of x = 0.95–0.98 and x = 0.99–1, respectively, revealing that two different mechanisms are involved depending on the Al content and the superlattice structure of the digitally-grown AlGaAs.