Ferroelectric properties of SrBi2TaNbO9 (SBTN) thin films were changed by the amount of Bi content in SBTN. We proposed that the addition of excess Bi to the SBTN thin films could be accomplished by heat treating the SBTN/Bi2O3/SBTN heterostructure fabricated by the radio frequency magnetron sputtering method. The Bi composition was controlled by changing the thickness of the inserted Bi2O3 from 50 to 400Å in the SBTN/Bi2O3/SBTN heterostructure. As the thickness of Bi2O3 films was increased from 0 to 100 Å, the grain grew faster and the ferroelectric properties improved. On the other hand, when the thickness, of Bi2O3 films was thicker than 150 Å, the ferroelectric properties deteriorated. In particular, when a 400 Å Bi2O3 layer was inserted between SBTN films, a Bi2Pt phase appeared and the Bi2O3 films remained between SBTN films, resulting in poor ferroelectric properties. A Bi2Pt phase was formed by the reaction between the platinum bottom electrode and Bi2O3 films. On the other hand, the leakage current density of SBTN thin films decreased with the increase of inserted Bi2O3 film thickness. As the thickness of inserted Bi2O3 films was increased from 0 to 50 Å, leakage current density abruptly decreased because Bi content of the SBTN thin films was increased from 8 mol% deficient to stoichiometric composition. As the thickness of inserted Bi2O3 films increased from 100 to 400 Å, leakage current density gradually decreased because the remaining Bi2O3 layer in SBTN thin films increased.

A negative temperature coefficient–positive temperature coefficient (NTC-PTC) composite thermistor with high performance was designed by glass/ceramic composing. The material exhibited low resistivity and a large negative temperature coefficient of resistivity. The minimum resistivity was the magnitude of 102 Ω cm, and the negative temperature coefficient of resistivity was better than −3% °C−1. The results showed that the large negative temperature coefficient of resistivity was closely related to the glass phase, and the NTC-PTC functional composite material was a kind of grain-boundary–controlled material.

A process has been invented for growing alumina (Al2O3) whiskers in the matrix of the aluminum-based metal matrix composite by the internal oxidation reaction between aluminum (Al) and molybdenum oxide (MoO3) at 850 °C. The whiskers were formed during the firing stage and distributed uniformly throughout the metal matrix. The fractional volume of the whiskers was about 30%, and their average size was 1 μm in diameter and 10 μm in length. The growth mechanism of the Al2O3 whiskers was studied. It was found that the nutrient for the growth of the whiskers was supplied from the molten Al at the base of the whiskers where they reacted with MoO3 forming the Al2O3 whiskers and the Al–Mo intermetallic phases.

Pure and reactive barium titanate (BaTiO3) and barium orthotitanate (Ba2TiO4) powders have been synthesized by an ethylene glycol (EG), polymerizationcomplexation route. The EG content affected the crystallization behavior and powder morphology. The BaTiO3powder, which had a particle size of approximately 100 nm, crystallized from amorphous to tetragonal phase on calcining at 700 °C for 1 h. Ball-milled BaTiO3 powder sintered to 97% relative density at 1200 °C after 2 h, with a grain size of approximately 200 nm. Ba2TiO4 powder required longer holding times or higher temperatures to be crystallized from the amorphous phase than did BaTiO3. In Ba2TiO4, the phase transformation between low-temperature monoclinic symmetry to high-temperature orthorhombic symmetry was observed by dilatometry and differential scanning calorimetry. A volume decrease of ∼0.5% accompanied the monoclinic-to-orthorhombic transformation on heating. The high-temperature orthorhombic phase could be retained down to room temperature y the addition of at least 6 wt% magnesia (MgO) stabilizer.

The mechanics for calculating the quantitative driving force of indentation-induced delamination of thin-film multilayers is presented. The solution is based on the mechanics developed by Marshall and Evans [D.B. Marshall and A.G. Evans, J. Appl. Phys. 56, 2632 (1984).] and extended to the general case of a multilayer by use of standard bending and thin-plate analyses. Presented and discussed are the specific solutions for the bilayer case that show that in the limit of zero thickness of either layer, the solution converges to the single-layer case. In the range of finite thickness, the presence of the superlayer increases the driving force relative to that possible for the original film alone and can be optimized to the experimental situation by proper choice of thickness, elastic constants, and residual stress. The companion paper “Quantitative adhesion measures of multilayer films: Part II. Indentation of W/Cu, W/W, Cr/W” discusses experimental results with copper, tungsten, and chromium thin films.

Sputtered copper and tungsten thin films both with and without tungsten and chromium superlayers were tested by using nanoindentation probing to initiate and drive delamination. The adhesion energies of the films were calculated from the induced delaminations using the analysis presented in “Quantitative adhesion measures of multilayer films: Part I. Indentation mechanics.” Copper films ranging in thickness from 150 to 1500 nm in the as-sputtered condition had measured adhesion energies ranging from 0.2 to 2 J/m2, commensurate with the thermodynamic work of adhesion. Tungsten films ranging in thickness from 500 to 1000 nm in the as-sputtered condition had measured adhesion energies ranging from 5 to 15 J/m2. The superlayer was shown to induce radial cracking when under residual tension, resulting in underestimation of the adhesion energy when the film was well adhered. Under conditions of weak adherence or residual compression, the superlayer provided an excellent means to induce a delamination and allowed an accurate and reasonably precise quantitative measure of thin film adhesion.

Solid-state amorphization was achieved in the Ni48Nb52 multilayers upon thermal annealing by gradually raising the temperature from 250 to 400 °C and staying at 400 °C for 2 h. More interestingly, before complete amorphization, a sequential disordering of first Ni and then Nb crystalline lattices was observed for the first time, and it was essentially the physical origin of an asymmetric growth of the amorphous interlayer during solid-state reaction reported previously in some binary metal systems. In another two multilayered samples with overall compositions of Ni64Nb36 and Ni70Nb30, thermal annealing under similar conditions resulted in the formation of two metastable crystalline phases with face-centered-cubic and hexagonal-close-packed structures, respectively, although an amorphous phase also appeared and coexisted with one of the metastable crystalline phases in the intermediate states. In the ion mixing experiment, such sequential disordering, as well as formation of metastable phases, was also observed in the respective Ni–Nb multilayers upon room-temperature 200-keV xenon ion irradiation. Comparatively, however, ion irradiation eventually induced complete amorphization in all the multilayers at the respective doses, indicating that ion-induced disordering frequently predominated in the competition between amorphization and the growth of a metastable crystalline phase. A Gibbs free energy diagram, including the free energy curves of the newly formed metastable crystalline phases, of the Ni–Nb system was calculated based on Miedema's model. The constructed free energy diagram can give reasonable explanations of the sequential disordering and the thermodynamic possibility of the formation of either an amorphous or a metastable crystalline phase, of which the free energy difference was quite small. It follows naturally that the phase selection, namely, which phase was more favored to be formed eventually than its competitors, was influenced or even determined by the kinetics involved in the respective processes.

The influence of the remnant magnetization of the soft magnetic particulates, used as a dispersed phase, on the redispersibility of magnetorheological (MR) fluids is discussed. Calculations of the magnetic interaction energy showed that for 33-vol% MR fluids based on particles of iron (∼6 μm), manganese zinc ferrite (∼2.3 μm), and nickel zinc ferrite (∼2.1 μm), the ratios of the magnetic interaction energy to the thermal energy were 161,000, 6400, and 3900, respectively. These calculations showed that even the seemingly small levels of remnant magnetization, associated with particulates employed in MR fluids, introduced significant dipole–dipole interparticle interactions. It is proposed that this interaction causes most MR fluids to show a tendency for “cake formation,” which makes it difficult to redisperse these fluids. Our modeling presented here also suggests practical strategies to enhance the redispersibility of MR fluids.

Chemical and electrochemical techniques were used for generating ensembles of randomly distributed organic and metal nanocylinders into the pores of nuclear track-etched polycarbonate membranes. This so-called “template method” makes it possible to synthesize a variety of materials including metals, ferromagnets, superconductors, semimetals, and conducting polymer and structures such as solid wires, tubules, composite nanostructures, and multilayers. Numerous interesting properties have been identified in relation to the nanoscopic dimensions of the materials.

Oxidation of polycrystalline nickel particles with an approximate median diameter of 158 μm has been studied by thermogravimetric measurements in the temperature range 773–1473 K. The oxidation was found to be thermally activated with an apparent activation energy of about 1.9 eV at temperatures below 1073 K and 1.2 eV at higher temperatures. Our data showed the qualitative features expected for oxidation of spherical metal particles. The kinetics was compared with a homogenous field coupled-currents theory for oxidation of spherical metal particles. Calculations using a median particle size or a distribution of particle sizes could only give a satisfactory fit to part of the experimental data. Possible explanations for the deviations in terms of space charge, grain boundary diffusion, grain growth, and sintering are discussed in this paper. Scanning electron microscopy studies of the particles after oxidation showed that a large difference exists in the surface structure and the degree of sintering between the particles oxidized at low and high temperatures.

Ideal spherical nonagglomerated Ni particles (mean diameter 0.62–1.12 μm) were prepared by ultrasonic spray pyrolysis of NiCl2 aqueous solution in the presence of 0.1 mass% of Pd, Cu, or Ni in an H2–N2 atmosphere at 900 °C. Incomplete reduction of the NiCl2 aqueous solution in the absence of additives was observed under the same conditions. Differential thermal and thermal-gravimetric analyses revealed a decrease in initial reduction temperature of NiCl2 from 375 to 275 °C by the addition of Pd, Cu, or Ni. The morphology of Ni particles was analyzed using scanning tunneling microscopy. The surface roughness of Ni particles was found to be controllable by addition of appropriate additives.

γ–Fe2O3 spherical particles with diameters between 5 and 3.5 nm—very uniform in size—have been prepared by laser pyrolysis of iron pentacarbonyl. The infrared spectra of the samples showed features that indicated different degrees of crystallinity according to the preparation conditions. Low saturation magnetization values (≈10 emu/g) and very high coercivities at low temperature (3000 Oe) have been found for the γ–Fe2O3 nanoparticles with the smaller particle size and the highest structural disorder. To explain the magnetic properties, it was necessary to consider additional anisotropies caused by the increase in surface and structural disorder as the particle size decreased.

Two kinds of aqueous precursor solutions are used to synthesize Mn–Zn ferrite powders: (i) nitrate (NO) precursor—derived from solutions of Mn(NO3)2, Zn(NO3)2, and Fe(NO3)3; and (ii) acetate (AC) precursor—derived from solutions of Mn(CH3COO)2, Zn(CH3COO)2, and Fe(NO3)3. The composition of the powders synthesized from the precursor AC is very uniform, whereas powders derived from the precursor NO have Mn and Zn segregated on the particle surfaces. In addition, the powders synthesized from precursor AC are solid spherical particles with fine porosity, whereas many hollow and fragmented particles are observed in the powder derived from precursor NO. Overall, the properties of Mn–Zn ferrite cores prepared from the precursor AC are superior to those prepared from the precursor NO. The reasons for the differences are explained and described in detail. The AC precursor powders synthesized by spray pyrolysis produced Mn–Zn ferrite cores with good magnetic properties.

An indirect observation of 90° domain reversal under the influence of a poling field process was undertaken by an x-ray diffraction study in the Pb0.88Eu0.08Ti1™y MnyO3 (y = 0, 0.01, 0.02, and 0.03) piezoelectric anisotropic system. The optimum condition kp → 0 was achieved for y = 0.02 composition. A large percentage of 90° domain rotation was necessary, but not a sufficient condition for the ultrahigh electromechanical anisotropy manifestation. A large microstrain originated by structural defects in unpoled samples seemed to play a crucial role in the attainment of this piezoelectric anisotropy. A breaking in the translational periodicity due to induced vacancy in Pb and O sites by Eu3+ and Mn2+ substitutions was manifested in the nonuniform variance of the tetragonality (c/a), the large microstrain, and the detriment of crystallinity observed.

Epitaxial and polycrystalline thin films of bismuth layer-structured ferroelectrics, SrBi2Nb2O9 (SBN) and SrBi2Ta2O9 (SBT), were prepared on single-crystal SrTiO3(001) and polycrystalline yttria-stabilized zirconia substrates, respectively, by the coating-pyrolysis process. The epitaxial relationship of the films and substrates was SBN, SBT (001)//SrTiO3(001) and SBN, SBT [100]//SrTiO3[100],[010], where pseudotetragonal indices were adopted for SBN and SBT. The lattices of the epitaxial films were found to be slightly strained owing to stress from the substrate. Atomic force microscopy observations showed that the epitaxial films as well as polycrystalline films consisted of round-shaped, islandlike grains of submicrometer size.

Electric domains in single-crystal and polycrystalline barium titanate (BaTiO3) have been observed by use of scanning electron acoustic microscopy (SEAM). A model is presented of the SEAM signal generation, spatial resolution, and contrast mechanism associated with the imaging of electric domains in ferroelectric materials. The SEAM signal is found to depend directly on the sum of the piezoelectric coupling coefficient and spontaneous polarization of the domain, on the charge density of the electron beam interaction volume, and inversely on both the permittivity and the elastic constants of the material. Application of the model to BaTiO3 yields a contrast of roughly 3.5% from 90° domain structures and 6.8% from 180° domain structures.

Stable and homogeneous alkoxide precursor solutions of lithium ethoxyethoxide and manganese ethoxyethoxide in 2-ethoxyethanol were synthesized by ligand exchange reaction of lithium isopropoxide and manganese 2-ethoxide, respectively, with 2-ethoxyethanol. [Li–Mn–O] precursor solution was prepared by mixing these modified alkoxide precursor solutions. LiMn2O4 powders were successfully synthesized by pyrolysis of the [Li–Mn–O] precursor powder in O2 temperature as low as 200 °C. The nanocrystalline LiMn2O4 powders 20–50 mm in diameter after heat treatment up to 700 °C consisted of the ordered (111) plane and performed with good cyclability as the cathode materials for Li secondary batteries.

Europium-doped yttrium oxide (Y2O3:Eu) thermographic phosphor films were deposited on Ni-alloy substrates using a novel and cost-effective electrostatic-assisted chemical vapor deposition (EACVD) technique. The thermoluminescence properties were studied under irradiation by an ultraviolet laser. It was found that crystallized Y2O3: Eu films could be deposited at a temperature as low as 550 °C. Annealing of the as-deposited films at higher temperatures (>1000 °C) improved the luminescence properties due to further crystallization processes. The correlation of the lifetime decay and temperature change of the films showed that the EACVD-deposited films are suitable for use in phosphor thermometry for high-temperature applications.

The effects of heat-treatment temperature on LiNbO3 thin films prepared by the polymeric precursor method were investigated. The precursor solution was deposited on Si(111) substrates by dip coating. X-ray diffraction and thermal analyses revealed that the crystallization process occurred at a low temperature (420 °C) and led to films with no preferential orientation. High-temperature treatments promoted formation of the LiNb3O8 phase. Scanning electron microscopy, coupled with energy dispersive spectroscopy analyses, showed that the treatment temperature also affected the film microstructure. The surface texture—homogeneous, smooth, and pore-free at low temperature—turned into an “islandlike” microstructure for high-temperature treatments.

The goal of this work was to address the technological problems associated with waveguide preparation by thermal- and electric-field–assisted K+–Na+ ion exchange in two types of soda-lime glass: common FTD and special pure GIL49. The number of modes, depth, profile, and the change in refractive index were measured for waveguides prepared at temperatures between 250 and 410 °C and electric-field values between 0 and 50 V/mm. Although the influence of some admixture content inside the glass was relatively high, all of these parameters were controlled accurately and repeatedly by the electric field.