The amorphous ternary metallic alloy Zr60Al15Ni25 was oxidized in dry oxygen in the temperature range 310 °C to 410 °C. Rutherford backscattering (RBS) and cross-sectional transmission electron microscopy (TEM) studies suggest that during this treatment an amorphous layer of zirconium-aluminum-oxide is formed at the surface. Nickel was depleted in the oxide and enriched in the amorphous alloy near the interface. The oxide layer thickness grows parabolically with annealing duration, with a transport constant of 2.8 × 10−5 m2/s × exp(−1.7 eV/kT). The oxidation rate may be controlled by the diffusion of Ni in the amorphous alloy. At later stages of the oxidation process, precipitates of nanocrystalline ZrO2 appear in the oxide near the interface. Finally, two intermetallic phases nucleate and grow simultaneously in the alloy, one at the interface and one within the alloy. An explanation involving preferential oxidation is proposed.

A novel metastable layered titanium phosphate has been synthesized by the treatment of layered titanates (Na2Ti3O7 and Na4Ti9O20) with 1–2 M phosphoric acid solution at 120–150 °C. Based on the data of 31P MAS NMR and IR spectroscopy, x-ray powder diffraction, and thermal and elemental analysis, the formula Ti2O3(H2PO4)2 · 2H2O was assigned to the novel compound. The layered nature of the compound was confirmed from n-alkylamine intercalation and the ion exchange behavior toward alkali, alkaline earth, and some transition metal ions.

This paper develops a mathematical model using mosaic patterns to characterize structural features of complex, multiphase, and multidimensional microstructures, such as those for cement paste. A multiphase microstructure can be characterized by m independent parameters; the first m– 1 parameters are equivalent to the volume fractions of the phases, while the final parameter describes the grain size, and thus, the spatial arrangement of the microstructure. An evaluation procedure for the parameters is given; they can be evaluated based on a 2D image, and then the 3D microstructure can be simulated by the present model. The relationship among the model parameters and material parameters, such as water-to-cement ratio and particle size distribution, are also established.

X-ray photoelectron spectroscopy (XPS) coupled with Fourier transform infrared (FTIR) and optical transmission spectroscopy (OTS) has been used for the characterization of silicon-carbon alloys (a-Si1−xCx: H, F) deposited via plasma, by varying the CH4 amount in SiF4–CH4–H2 feeding mixture. XPS measurements have shown that carbon-rich a-Si1−xCx: H, F alloys include large amounts of fluorine (>11 at. %), which make the films susceptible to the air oxidation. In addition, the effect of the alloying partner carbon on the valence band (VB) and on the VB edge position of amorphous silicon is also described.

Amorphous microwires, obtained by the glass-coated melt-spinning method having diameters in the range of micrometers, can exhibit perfectly square (single and large Barkhausen jump) or quasi-anhysteretic hysteresis loops, depending on the easy magnetization direction determined by the intrinsic magnetoelastic anisotropy. The thermoelastic internal stressed frozen-in during the fabrication that model the domain structure are here calculated by considering the classical theory of elasticity. A complex stress distribution is obtained having magnitude of 103 MPa. Circular stresses turn out to be predominant, which arises from the composite nature of the microwire (metallic nucleus and insulating glass coating having different mechanical and thermal properties).

Barium titanate has been prepared at room temperature from a well-characterized crystalline barium titanium oxo alkoxide by reaction with acetone. An aldol condensation apparently supplies oxygen to condensing oxo alkoxide clusters. Transmission electron microscopy confirms that the crystallites so formed are dense and perfect with an average size of approximately 85 Å. Characterization of reactants and products provides a tentative understanding of structural evolution and the intermediates of the transformation. Crystalline SrTiO3 and BaZrO3 were also formed at room temperature by this same method.

Electronic structure calculations were carried out for bcc iron (Fe) clusters with or without hydrogen (H), and also involving a vacancy, using the self-consistent Discrete Variational method (DV-Xα) within the local density functional formalism. Bonding characteristics investigated show the following: (i) Interstitial H notably decreases interatomic Fe–Fe bond strengths, but acts over a small distance (within 0.3 nm). (ii) In the perfect Fe lattice field, interstitial H feels a repulsive force at any site. As a result of lattice relaxation, volume expansion may be expected. (iii) H in combination with a vacancy prefers a position shifted from the octahedral site toward the vacancy. This is fairly consistent with an experimental result.

The order-disorder states of the A-site vacancy of PBN solid solution affected by different thermal treatments were studied with the aid of High Resolution Electron Microscopy (HREM). PBN ceramics around the morphotropic phase boundary were prepared through two routes to control ordering degree of the A-site vacancy: (1) samples through quenching processes resulted in chaotic states of the A-site vacancies and misfit anti-phase boundary; (2) samples through slow cooling led to an ordered structure of the vacancies in the A1-site. The ordered A1-site vacancies were modulated by interchanges of the sublattices of the ordered vacancies and the Pb2+ cations in the A1-sites along both and orientations, forming a narrow discommensurate wall between two anti-phase domains. The anti-phase domains were observed as a regular belt structure with dimensions of about 45 nm × (≥120) nm. The belt nano-domain structures were a result of quasi-equilibrium thermodynamic processes.

Polycrystalline diamond films were processed in a direct current plasma produced by a self-focused electron beam using combinations of H2, O2, and He as the processing gas. The film surfaces were observed by scanning electron microscopy, and characterized by x-ray photoelectron spectroscopy. It was found that for the case in which O2 was included in the processing gas, a high density of etch pits appeared on (100) faces of diamond grains, and oxygen was either physisorbed or chemisorbed at the film surface. It was demonstrated that the etching apparatus used was capable of forming at least a 5-μm wide pattern of polycrystalline diamond film.

A systematic experimental study of solute migration during thermal annealing and oxidation of type 2011 aluminum alloy is described. Specimens of this alloy were implanted with Ti, Cr, or Al ions to doses in the range 2 × 1015–2 × 1017 ions cm-2. The implanted substrates were annealed at 500 °C in vacuum or an oxygen atmosphere and analyzed with Rutherford backscattering and scanning electron microscopy. Changes to the alloy composition resulting from segregation of constituents in the near surface region occurred for both implanted and unimplanted specimens, though the effect was substantially more pronounced following implantation. In addition, segregation was affected by the type and dose of the implanted ion. For the Ti implants under oxidizing conditions, the Ti ions were found to diffuse toward the surface and form a thick oxide layer. Segregation of Cu and Pb/Bi then occurred below this oxide layer. In contrast, implanted Cr ions under similar conditions were observed to diffuse into the substrate with only a thin oxide layer being formed at the surface. Consequently, Cu and Pb/Bi segregated close to the surface.

Using a Plasma Assisted Sintering (PAS) process, submicron size, silicon nitride powders were consolidated to >99% of the theoretical density (TD) at 1750 °C in less than 5 min with retention of the a phase and the submicron grain size. The silicon nitride powders were sintered with 5 wt.% Y2O3 and 5 wt.% Y2O3 + 5 wt. % MgAl2O4 additives. The PAS processing method for the silicon nitride additive mixtures is attractive for retention of fine-grained microstructures favorable for superplastic deformation. Post superplastic forming heat treatments to transform the α−Si3N4 to lath-like, creep-resistant β−Si3N4 is another feature of the present processing method.

A process for the manufacture of very thin parallel wires has been developed. A series of parallel silver wires have been written for the study of one-dimensional electron transport. The wires are approximately 200 nm wide and 8 mm long. The method used can produce longer and thinner wires.

Six near stoichiometric, NiAl single-crystal alloys, with 0.05−1.5 at.% of Hf and Zr additions plus Si impurities, were microstructurally analyzed in the as-cast, homogenized, and aged conditions. Hafnium-rich interdendritic regions, containing the Heusler phase (Ni2AlHf), were found in all the as-cast alloys containing Hf. Homogenization heat treatments partially reduced these interdendritic segregated regions. Transmission electron microscopy (TEM) observations of the as-cast and homogenized microstructures revealed the presence of a high density of fine Hf (or Zr) and Si-rich precipitates. These were identified as G-phase, Ni16X6Si7, or as an orthorhombic NiXSi phase, where X is Hf or Zr. Under these conditions the expected Heusler phase (β′) was almost completely absent. The Si responsible for the formation of the G and NiHfSi phases is the result of molten metal reacting with the Si-containing crucible used during the casting process. Varying the cooling rates after homogenization resulted in the refinement or complete suppression of the G and NiHfSi phases. In some of the alloys studied, long-term aging heat treatments resulted in the formation of Heusler precipitates, which were more stable at the aging temperature and coarsened at the expense of the G-phase. In other alloys, long-term aging resulted in the formation of the NiXSi phase. The stability of the Heusler or NiXSi phases can be traced to the reactive element (Hf or Zr) to silicon ratio. If the ratio is high, then the Heusler phase appears stable after long time aging. If the ratio is low, then the NiHfSi phase appears to be the stable phase.

Dense, crystalline, glass-ceramic coatings containing calcium metaphosphate and aluminum phosphate were prepared on aluminum oxide substrates by a three-step method. The processing involved glass (40 mol% CaO, 10 mol% Al2O3, 50 mol% P2O5) formation, deposition of a glass particle coating, and heat treatment to sinter the glass and crystallize the phosphates. Sintering and microstructure evolution were influenced by wet coating thickness, heat-treatment temperature, time, and heating rate. Heat treatment for 1 h at 725 °C using a 50 °C/min heating rate was found to give a dense, crack-free coating. The resultant coating microstructure has spherulitic morphology (0.3 μm size) with aluminum phosphate in the center of the spherulite. The hardness of the fully crystallized glass-ceramic coating was ∼5.2 GPa.

Metastable liquid-liquid immiscibility region in the Al2O3–SiO2 system was calculated by a regular solution model using three sets of liquidus data from the stable phase diagrams reported. These calculations indicated that the immiscibility region was richer in Al2O3 composition than those reported before. A miscibility gap calculated using the liquidus data reported by Klug et al. [F. J. Klug, S. Prochazka, and R. H. Doremus, J. Am. Ceram. Soc. 70, 750 (1987)] (model A) ranged from 2.6 to 71 mol % Al2O3 at around 1000 °C, which was the most compatible result with the idea that metastable pseudotetragonal mullite crystallized at around 1000 °C became Al2O3-rich composition due to the immiscibility phase separation before mullitization among three sets of liquidus data.

Zn-doped YBa2Cu3O6+δ (YBCO) single crystals were fabricated by the solute-rich liquid-crystal pulling (SRL-CP) method. The Zn content of x ranged from 0.0035–0.029 and almost uniformly distributed in YBa2(Cu1−xZnx)3O6+δ. There is a nearly linear relationship between the added Zn content in the liquid and the analyzed Zn content in the liquid/in the crystal. When the added Zn content Cl was 1.086 at. %, decreasing of growth temperature led to increasing growth rate. However, growth temperature had no obvious effect on the doped Zn content in the crystal Cs, the Zn content in the flux Cl, and the effective distribution ratio of k′. In addition, growth spirals on the grown crystal surface were observed by atomic force microscopy (AFM). X-ray Laue pattern and RBS measurements are indicative of good crystallinity of YBa2(Cu1−xZnx)3O6+δ. Critical temperatures of Tc changed from 89 to 57 K when the Zn content x ranged 0.0035 to 0.029 after appropriate oxygenation.

One composition of Pr–Ce mixed oxide and a range of compositions of Pr–Zr mixed oxide were prepared by coprecipitation methods and characterized by x-ray powder diffraction, thermogravimetric analysis, and x-ray photoelectron spectroscopy. Based on phases formed, the PrOy—ZrO2 system in an oxygen-containing atmosphere at moderate temperatures (up to 800–1000 °C) is analogous to that of CeO2–ZrO2. Addition of either Ce or Zr to pure Pr oxide affects both the total amount of oxygen that can be reversibly exchanged between oxide and gas phase and the kinetics of the redox processes. Ce dramatically increases the amount (per Pr atom) and lowers the temperature of exchange, Zr slightly decreases the amount and also lowers the temperature of exchange, and both modifiers speed up the rate. These observations are rationalized in terms of bulk and surface structural features of the mixed oxides.

X-ray diffraction (XRD) and Raman spectroscopy have been used for the study of the bi-intercalation of SbCl5 into a stage 5 FeCl3-graphite intercalation compound (GIC). The stage 5 FeCl3-GIC is prepared by an ordinary two-bulb method with the temperature of graphite at 788 K and that of FeCl3 at 573 K. The FeCl3-SbCl5-graphite bi-intercalation compound (GBC) with one SbCl5 layer is obtained when the temperature of the stage 5 FeCl3-GIC is held at 443 K and the temperature of SbCl5 at 373 K in the two-zone system. The stacking sequence of the GBC is found to be an admixture of G(FeCl3)GG(SbCl5)GGG(FeCl3)G and G(FeCl3)GGG(SbCl5)GG(FeCl3)G by XRD, where G, (FeCl3), and (SbCl5) are the graphite, FeCl3, and SbCl5 layers, respectively. The Raman spectrum of the GBC shows two peaks associated with the and modes at 1588 cm−1 and 1610 cm−1, respectively. For the temperatures of stage 5 FeCl3-GIC at 443 K and SbCl5 at 403 K in the two-zone system, the FeCl3-SbCl5-GBC with two SbCl5 layers is obtained. The stacking sequence of the GBC is determined to be an admixture of G(FeCl3)GG(SbCl5)GG(SbCl5)G(FeCl3)G and G(FeCl3)G(SbCl5)GG(SbCl5)GG(FeCl3)G In the Raman spectrum of this GBC, two peaks associated with the mode are observed at 1616 and 1624 cm−1.

Electromagnetic characterization and high resolution transmission electron microscopy have been conducted on the same 8° [001] symmetrical (010) tilt boundary in a naturally grown, bulk-scale bicrystal of Bi2Sr2CaCu2O8 + x (BSCCO-2212). The resistive transition showed excess resistance above and below Tc, suggesting some weak coupling at the boundary, but the inter- and intragranular voltage-current characteristics, irreversibility fields, and critical current density (Jc) values were very similar and characteristic of strongly coupled grains and grain boundary. The misorientation was accommodated by a set of partial dislocations with the Frank spacing of 1.9 nm. The dislocation cores appeared to be separated by relatively undistorted regions of crystal. The Jc, values at 25 K exceeded 103 A/cm2 in fields of several tesla, more than two orders of magnitude larger than that found earlier in [001] twist boundaries of BSCCO-2212. This result is consistent with the view that low angle [001] till boundaries play an important role for current transport in polycrystalline BSCCO tapes.

Synthesis of GeS2 via a sol-gel process using germanium ethoxide and hydrogen sulfide in toluene resulted in a gel aggregate with an apparent Ge/S ratio 1:1.8. Special precautions were necessary to protect the reaction mixture from water contamination which produced GeO2. Results indicated that the main source of water was the hydrogen sulfide gas. Heat treatment of the produced GeSx gel yielded a product with Ge/S ratio 1:2.3. The sol-gel prepared materials and their heat-treated products were characterized by various methods.