The objective of this paper is to report on the anelastic, i.e., reversible and time-dependent, deformation behavior of precursor-derived amorphous ceramics. Therefore compression experiments under constant and varying stresses up to 250 MPa were performed at a temperature of 1400 °C. In the stress change experiments anelasticity was observed. By comparison of both types of experiments, the anelastic strain rate was determined. It decreased inversely proportional to the time after the stress change and was independent of the preceding duration of the test. Furthermore, deviations from the deformation behavior expected according to the free-volume-model, which were observed in compression creep tests, could be explained by anelastic behavior.

The superfine Fe–B–Si–Mo and Fe–B–Zr–Nb alloys were prepared by liquidus casting in which the levitation melting combining with the rapid solidification was used. The melt was poured into a copper mold at various temperatures, and a superfine granular microstructure was obtained at liquidus temperature. The behavior of Cu and Ag addition to Fe–B–Si–Mo and Fe–B–Zr–Nb alloys was studied. Both adding Cu and Ag to Fe–B–Si–Mo and Fe–B–Zr–Nb alloys had influence on refining the alloys. The refinement effect of adding Cu is stronger than that of adding Ag in Fe–B–Zr–Nb alloy.

A composite film of titanium dioxide (TiO2) nanoparticles and hydrolyzed styrene–maleic anhydride alternating copolymer (HSMA) was obtained on a substrate when a TiCl4 solution was heated at 80 °C with a spin-cast thin HSMA film present in the solution. The composite film was characterized with x-ray photoelectron spectroscopy and transmission electron microscopy. Results revealed that TiO2 nanoparticles discretely dispersed on the polymer layer, and they were dominantly rutile phase, of a spherical shape and 18–20 nm in diameter. In contrast, mainly amorphous TiO2 powders were obtained from the identical TiCl4 solution by drying the solution with the absence of the HSMA film. The TiO2 nanoparticles deposited on the polymer layer were regarded to contain polymer chains, and a multilayered core–shell model was suggested for the formation of these composite nanoparticles. It is regarded that the core of a composite particle consisted of an anatase-phase TiO2 colloidal nanoparticle, while the shell layer was made of rutile-phase TiO2/polymer multilayers; the composite particles formed by a layer-by-layer self-assembly of TiO2 and polymer layers analogous to biomineralization, where the polymer promoted the crystallization of rutile-phase TiO2 when TiO2 deposited from solution.

A nanocomposite structure was induced in gel of composition 60CuO · 40SiO2 (mol%) by first of all precipitating nano-sized copper particles by a reduction treatment and subsequently subjecting these to a controlled oxidation treatment. The particle size was of the order of 6.8 nm. Alternating current (ac) conductivity measurements were carried out on different specimens in the temperature range 300 to 630 K covering a frequency spectrum 0.1 kHz to 2 MHz. The ac conductivity was found to have a variation with frequency given by ωs, ω being the angular frequency and s the frequency exponent. The analysis of the variation of s as a function of temperature led to the conclusion that an overlapping large polaron tunneling mechanism was operative in this system. The effective barrier height for polaron transfer for infinite intersite separation was found to be almost twice in the case of the precursor gel as compared to that for the composite with the interfacial amorphous phase.

NiAl–AlN + Cr composites were produced by blending cryomilled NiAl powder with approximately 10 vol% Cr flakes. In comparison to the as-consolidated matrices, hot isostatically pressed Cr-modified materials did not demonstrate any significant improvement in toughness. Hot extruded NiAl–AlN + 10.5Cr, however, possessed a toughness twice that determined for the base NiAl–AlN alloy. Measurement of the 1200 to 1400 K plastic flow properties revealed that the strength of the composites was completely controlled by the properties of the NiAl–AlN matrices. This behavior could be successfully modeled by the Rule-of-Mixtures, where load is shed from the weak Cr to the strong matrix.

A relatively low-cost, high-efficiency method is reported to synthesize AlN nanowires, using carbon nanotubes as templates. The AlN nanowires were fabricated at 1100 °C, for 60 min. The diameters of the product could be roughly controlled by the sizes of carbon nanotubes selected as starting materials. The AlN nanowires obtained were among the thinnest ever known. X-ray diffraction, selected-area diffraction, energy dispersive spectroscopy, and high-resolution transmission electron microscopy, etc. were employed to characterize the products, which were found to be single crystals with some defects. The axes of the nanowires are normal to {1010} crystal planes. A new synthesis mechanism is proposed.

The present work shows how data obtained in a depth-sensing indentation test using a Knoop indenter may be analyzed to provide elastic modulus and hardness of the specimen material. The method takes into account the elastic recovery along the direction of the short axis of the residual impression as the indenter is removed. If elastic recovery is not accounted for, the elastic modulus and hardness are overestimated by an amount that depends on the ratio of E/H of the specimen material. The new method of analysis expresses the elastic recovery of the short diagonal of the residual impression into an equivalent face angle for one side of the Knoop indenter. Conventional methods of analysis using this corrected angle provide results for modulus and hardness that are consistent with those obtained with other types of indenters.

A method to measure friction during scratching at linearly increasing loads in a commercial atomic force/friction force microscope (AFM/FFM) has been developed. The normal load was increased in small increments over the required range for the scratch using a software module while the friction signal was measured via a breakout box and data acquisition computer. Topography images of the scratch were obtained in situ with the AFM in tapping mode with minimal loss of damage event information. This technique was employed to study the scratch resistance of hard amorphous carbon coatings of thicknesses ranging from 20 nm down to 3.5 nm deposited by different commercially available deposition techniques on a silicon substrate.

Employing the n-body potentials of the Ni–Zr and Ni–Ti systems, we performed molecular dynamics simulation to study the relative stability of the terminal solid solutions versus the corresponding amorphous states as a function of solute concentrations. The terminal solid solutions transformed into amorphous states spontaneously when the solute concentrations were beyond the maximum allowable values; i.e., the critical solubilities were determined to be 14 at.% Zr in Ni and 25 at.% Ni in Zr for Ni–Zr system and 38 at.% Ti in Ni and 15 at.% Ni in Ti for the Ni–Ti system. The physical implication of the critical concentrations, as well as their correlation with the glass-forming abilities of the Ni–Zr and Ni–Ti systems, is discussed.

Typical microelectromechanical systems (MEMS) devices and packages are composed of micron-scaled structures. Experimental investigations on the effect of size on the deformation behavior of simple structures have shown that the deformation behavior of metals and polymers is size dependent. The size dependence in small structures is attributed to the contribution of nonnegligible strain gradients. In this work, torsion and bending of micron-sized rods and plates were analyzed by using a two-parameter model of strain-gradient plasticity. Microrod torsion and microplate bending experimental data were analyzed to determine the magnitude of the strain-gradient material parameters. The parametric analyses showed that conventional analysis is applicable only when the size of the structure is significantly larger than the material parameters, which are typically in the micron range. Strain-gradient analysis of micron-sized rod revealed that the presence of strain gradient increased the torque by three to nine times at the same twist. For MEMS structures with micron-sized features, conventional structural analysis without strain gradient is potentially inadequate, and strain-gradient analysis must be conducted to determine the elastoplastic behavior in the micron scale.

The microstructural characteristics of ion-beam-sputtered conductive SrRuO3 films, such as interfacial reactions, which govern growth behavior, defects, and thermal stability, were investigated using transmission electron microscopy. On a Si substrate, two binary constituents of SrRuO3, i.e., SrO and RuO2 were shown to have quite different reaction behaviors. The reduction of the RuO2 constituent to elemental Ru by Si led to an unstable contact of SrRuO3 on the Si substrate. Possible reaction thermodynamics are suggested, which are based on the formation energies of the corresponding reactions. In the case of films grown in an oxygen-deficient atmosphere, stacking faults were observed. The stacking faults originated from twinning on the {111}pc plane to accommodate the oxygen deficiency in the growth atmosphere by changing the arrangement of RuO6 octahedra from corner to one of face sharing.

Electrical transport properties, electrical conductivity, and thermoelectric power of a single-crystalline Mn0.45Zn0.43Fe2.12O4 were measured as functions of temperature in the range of 25 to 1000 °C. According to the small polaron hopping model, the values of the activation energy for small polaron hopping (EH) were obtained from the conductivity data in three different temperature regions: 0.032 eV for T < TC, 0.12 eV for TC < T < 600 °C, and 0.25 eV for 600 °C < T < 1000 °C. The behavior of conductivity and thermoelectric power data above TC is discussed in connection with cation redistribution.

This paper describes a novel technique for determining the constitutive equation of elastic–plastic materials by the indentation technique using plural indenters with different apex angles. Finite element method (FEM) analyses were carried out to evaluate the effects of yield stress, work hardening coefficient, work hardening exponent, and the apex angle of indenter on the load–depth curve obtained from the indentation test. As a result, the characterized curves describing the relationship among the yield stress, work hardening coefficient, and the work hardening exponent were established. Identification of the constants of a constitutive equation was made on the basis of the relationship between the characterized curves and the hardness given by the load–depth curve. This technique was validated through experiments on Inconel 600 and aluminum alloy. The determined constitutive equation was applied to the FEM analyses to simulate the deformation including necking behavior under uniaxial tension. The analytical results are in good agreement with experimental results.

The structures and microstructures of a range of Aurivillius phases were investigated by transmission electron microscopy. Systematic rows of superlattice reflections arising from tilting of octahedra around the c axis were identified, and their intensities at room temperature were shown to diminish as the tolerance factor (t) of the perovskite blocks increased. For compounds with t's approaching 1, no superlattice reflections were observed. the paraelectric-to-ferroelectric phase transition temperature (Tc) was monitored through permittivity measurements as a function of temperature, and Tc was also shown to decrease as t increased. Consequently, the onset of octahedral tilting and Tc appeared to be strongly related Aurivillius phases. Planar defects arising from the structural phase transitions and from stacking irregularities were also discussed.

Conducting polymers are required for applications such as radio frequency interference shielding, primerless electrostatic painting, and static discharge. We have used vapor-grown carbon fiber (VGCF) as an additive to investigate conducting thermoplastics for these applications. The electrical properties of VGCF/polypropylene (PP) and VGCF/nylon composites are very attractive compared with those provided by other conventional conducting additives. Because of the low diameter of the VGCF used, the onset of conductivity (percolation threshold) can be below 3 vol%. Because of the highly conductive nature of the fibers, particularly after a graphitization step, the composites can reach resistivities as low as 0.15 Ω cm.

Raman and infrared measurements of the LiB3O5 (LBO) crystals were completed. The experimental results shown here are more and stronger Raman lines and infrared absorption peaks, which implies that the external vibrations of the trigonal (BO3)3− and tetrahedral (BO4)5− ions, especially the former, in the six-membered boron–oxygen rings at the low wave number are strong and the internal vibrations of the (BO4)5− ions above 200 cm−1 are stronger than those of the (BO3)3− ions if compared with the Raman spectra of BaB2O4 crystals. These are caused due to the slope and distortions of the B3O7 rings and their BO3 and BO4 units in LBO, which change the structural rigidity of the crystals, intensify the long-range electrostatic force and short-range molecular force, and shorten the ultraviolet absorption edge.

Ba4Nd2Ti4Ta6O30 dielectric ceramics with high-Ε and low dielectric loss were modified to improve the temperature coefficient of dielectric constant. Through partial substitution of Ti4+ for Ta5+, a significantly reduced temperature coefficient of dielectric constant (tΕ = –664p pm/°C) combined with a dielectric constant above 110 and a low dielectric loss (tanδ–0.0005 to 0.0006 at 1 MHz) resulted in the nonstoichiometric dielectric ceramics with nominal compositions Ba4Nd2Ti4+xTa6-xO30?x/2 (x = 0.8–1.2).

A cryptomelane-type manganic acid (CMA) exchanged by divalent transition-metal cations was studied by means of x-ray diffraction, electron microscopic observation, electron spin resonance, infrared spectra, and electron spectroscopy for chemical analysis. Especially the last three techniques were decisive for the chemical speciation of manganese oxide systems. The findings clearly eliminated a redox process as the principal process for cation uptake in the α–MnO2 phase. Transition-metal cations are stoichiometrically exchanged on this material on an equivalent basis similarly with alkali and alkaline-earth metal cations, except Fe2+. The last ion is oxidized to Fe3+ through a redox reaction with Mn3+ in the a–MnO2. The CMA is a mixed-valence compound represented by H2Mn2IIIMn6IVO16 2.3H2O. Two moles of tunnel protons are exchangeable to give 2.70 mequiv/g for the calculated ion-exchange capacity.

Results are presented of a study on the mechanical stress dependence of the resistance of polycrystalline silicon (Poly-Si) films doped with different atomic species. Two types of Poly-Si film implanted with boron and phosphorus ions were studied, namely, B-doped films of 400 nm and P-doped films of 250 nm thickness, which were deposited by low-pressure chemical vapor deposition at 620 °C on thermally oxidized silicon wafers. The film doping was done by ion implantation at 50 keV, with a dose of boron and phosphorus of 2 × 1014 and 5.3 × 1014 cm−2, respectively. The Poly-Si films were annealed in a N2 ambient at 1000 °C for 20 min to activate the implanted atoms. A controlled amount of external stress was applied to the silicon wafers to study the impact on the electrical performance of the implanted Poly-Si resistors. The resistance of the B-doped Poly-Si films is shown to increase by the mechanical stress, while the resistance of the P-implanted Poly-Si films remained unchanged. It is concluded that this difference is related to the structural differences between Poly-Si films implanted with boron and phosphorus, respectively.

Five glasses in the system SiO2 · CaO · P2O5 have been synthesised via sol-gel method. The textural properties of the calcined glasses have been studied using mercury intrusion and N2 adsorption porosimetries. The glasses with higher SiO2 content showed lower pore volume, smaller diameters in the meso- and macropore regions, and higher surface areas. The pore morphology in the mesopore range was influenced by the SiO2 content, where there was a transition from ink bottle to cylinder shaped pores.