Mesostructured non-oxidic materials with cubic Ia-3d symmetry were prepared by linking [Sn2Se6] 4- clusters with Pt2+ in the presence of surfactant molecules. The use of long chain pyridinium-based surfactants (octadecyl- and eicosadecyl) afforded materials with exceptionally high cubic pore order and single-crystal particle morphology. By contrast trimethylammonium-based surfactants produced cubic mesostructured solids with inferior overall quality. We have also synthesized materials with significantly lower surfactant content by increasing the Pt2+:[Sn2Se6] 4- molar ratio, while maintaining the cubic pore symmetry. All materials are semiconductors with energy band-gap in the range 0.9<Eg<1.8 eV.

The Al-Mg-Si (6xxx-series) alloy system is a precipitation hardened alloy gaining much of its strength from precipitate phases acting as pinning centers for dislocation movement. Five years ago, Zandbergen, Andersen and coworkers identified the crystallography of the so-called β″ phase, one of the main hardening phases, using solely electron microscopy techniques [1]. Later, several other phases have been identified using high resolution microscopy. To solve the crystallography of these phases and to get an increased understanding of the electronic structure and bonding, ab initio modeling has proven to be a valuable tool. We present results from calculations on two recently discovered phases and show how ab initio modeling can give insight into the bonding trends and electronic structure of the phases in this alloy system.

BaTi4O9 is a photocatalyst with a pentagonal prism tunnel structure. It has been hypothesized that the tunnels promote the separation of photogenerated carriers and, therefore, lead to the spatial separation of oxidation and reduction half reactions. This hypothesis has been tested by observing the distribution of reduced and oxidized reaction products on BaTi4O9 surfaces over a wide range of orientations. The surface orientations were determined by electron backscattered diffraction and atomic force microscopy was used to examine the structure of the surface both before and after the deposition of reaction products. Reduction products (Ag0) are distributed uniformly. The distribution of oxidation products (PbO2) is also not correlated to the surface orientation or to the orientation of the tunnels with respect to the surface. Based on these observations, we conclude that the tunnels in this structure do not separate photogenerated charge carriers and that this mechanism is not responsible for this compound's relatively high photocatalytic activity.

Bismuth nitrate basic, which chemical content is given by 4BiNO3(OH)2.BiO(OH), was studied for anion-intercalation or anion-exchange properties. A crystal structure of the bismuth nitrate basic has not been known. In the present study, its XRD pattern was indexed using a possible orthorhombic system having the lattice parameters of ao=3.021(1) nm, bo=3.029(1) nm and co=0.9572(3) nm. This compound was found to incorporate CH3COO-, halides and several oxyanions including CO32-. Incorporation of these anions by this solid was evidenced by broadening of infrared absorption band by NO3-, suggesting involvement with NO3- ions. Intercalation of CO32- by the bismuth nitrate basic in full extent yielded a bismutite represented by the chemical composition Bi2O2CO3. The bismuth nitrate basic will serve as a new host for anion-intercalation and anion-exchange.

A novel structure map was developed for metal-rich pnictides and chalcogenides M2Q, with M being an element of groups 3 – 5, and Q of groups 15 – 16. To date, this family exhibits eleven different structure types, which are separated in well-defined domains in this structure map. The map comprises a combination of atomic factors as the abscissa, namely principal quantum numbers, valence-electrons, and radii, and a structural factor as the ordinate, which is the averaged coordination number of the Q atoms. We demonstrate in this contribution how this new map can be and has been used to predict crystal structures of new materials from atoms up. First attempts to expand this concept towards different stoichiometries are described.

In present study LiMn2O4-xFx were prepared by the sol-gel method. X-ray diffraction (XRD) and scanning electron microscope (SEM ) were employed to detect the microstructure of the reaction products. It were found perfect crystal particles were obtained, and its' size were uniform in 1∼2 μ m. The specific capacity and cycleability were measured basing on battery program control test system. The results shown the substitution of F for O increased the specific capacity of the material at the cost of the cycleability due to more Mn3+ and less Mn4+ existed in the material. The exist of Mn3+ would reduce cycleability of cathode material due to the Jahn-Teller effect which were caused by the deformation of the crystal structure.

In order to explain magneto-elastic and pressure measurements in doped colossal magneto-resistance manganites, we postulate a doublet-triplet model and use it to predict the occurrence of the various phase transitions.

Thin plate-like [Ca2(Co1-xCux)2O4] y CoO2 single crystals were successfully grown by the flux method using SrCl2 solvent. The largest crystal size was approximately 3 × 3 × 0.01 mm3. The copper concentrations, x, in the crystals were found to be depending on each crystal, suggesting a certain solid-solution range of copper in the present system. The obtained crystal showed low resistivity (∼4.3mQcm) and high Seebeck coefficient (∼160μVK-1) at 300K. The crystal showed anisotropic magnetization with larger magnetization under H ∥ c. Irreversible magnetization behavior below ∼90K was also found under H ∥ c.

Using elemental multilayers with designed composition and ultrathin repeating subunits (λ=20 A) we have prepared nickel monosilicide and nickel germanide directly without the formation of any intervening phases. When the same synthetic strategy is used to prepare nickel-silicon-germanium compounds the first nucleated phase is a ternary phase with the NiAs structure.

Anatase (A), rutile (R) and amorphous phase TiO2 thin films have been prepared by RF magnetron sputtering on unheated glass substrates by controlling the total pressure of sputtering gases (Ar + O2) and the substrate bias. The crystal structures of the films were confirmed by x-ray diffraction and Raman scattering. The analysis of optical absorption data for A- TiO2 film shows an energy bandgap (Eg) of 3.2 eV (indirect extrapolation) and ∼ 3.5 eV (direct extrapolation). On the other hand, R-TiO2 film shows Eg ∼ 2.9 eV (indirect) and 3.2 eV (direct). The latter film also shows the presence of amorphous regions with Eg ∼ 3.0 eV (indirect) and 3.8 eV (direct). The bandgap of both the films, obtained using indirect extrapolation, has a value range consistent with the previous measurements.

Powder mixtures of Ti/Si/C, Ti/SiC/C, Ti/Si/TiC, Ti/SiC/TiC and Ti/TiSi2/TiC were used for the synthesis of Ti3SiC2 by using a pulse discharge sintering (PDS) process. The Ti/Si/TiC powder was found to be the best among the five powder mixtures for the Ti3SiC2 synthesis. The highest content of Ti3SiC2 can be improved to about 99wt% at the sintering temperature of 1300°C for 15 minutes. The relative density of all the synthesized samples is higher than 98–99% at the sintering temperature above 1275°C. The nearly single phase Ti3SiC2 was found to show plastic deformation at room temperature and a good machinability. Both electrical and thermal conductivity were found to be more than two times of the value of a control pure Ti sample. The high-temperature mechanical tests confirmed that the Ti3SiC2 samples synthesized by the PDS process displayed a comparable performance with those fabricated by the other techniques.

New TeMoV and TeMo(V,Nb) bronze type phases have been obtained during the heat-treatment (600° C in N2) of the corresponding precursor mixture. Both mixed oxides seem to be structurally related to one of the crystalline phases proposed in Mo-V-Te-Nb-O catalysts. Chemical and microstructural characterization revealed the formation of an orthorhombically distorted cell deriving from a bronze type HTB structure, which does not behave as a bronze type structure in the chemical sense. Microstructural details responsible for the new unit cell are discussed in terms of tellurium location inside the hexagonal tunnels and based on the structural model proposed.

SiO2-coated Ni75Fe25 nanoparticles were prepared using a wet chemical method and their structure and magnetic properties were investigated using x-ray diffraction, high-resolution transmission electron microscopy, and a superconducting quantum interference device magnetometer. The SiO2 material was in an amorphous state. The Ni75Fe25 nanoparticles were in a simple cubic state and contained inner oxide (Ni-oxide and Fe-oxide) cores whose size decreased with increasing calcination temperature. The nanoparticles were basically in the ferromagnetic state. Their saturation magnetization increased with increasing calcination temperature, whereas their coercivity decreased with increasing calcination temperature. The nanoparticles exhibited strong temperature-dependent magnetic behaviors. The Bloch exponent fell from 1.5 for the bulk to smaller values and decreased with increasing oxide content, while the Bloch constant was much bigger than that for bulk and increased significantly with oxide content. The value of coercivity decreased with increasing temperature, and this decrease was more pronounced for the nanoparticles containing high oxide content. The exchange anisotropy arising from the exchange coupling across the Ni75Fe25/oxide interfaces was examined and was used to interpret the observed temperature-dependent behaviors.

The formation of single phase FeP nanocrystals has been achieved by the reaction of Fe(III) salts (iron(III)acetylacetonate (Fe(acac)3) and iron(III)chloride (FeCl3)) with tris(trimethylsilyl)phosphine in trioctylphosphine oxide (TOPO)/trioctylphosphine (TOP) at elevated temperatures. The sizes of nanoparticles formed differ markedly depending on the initial iron salt used. Use of Fe(acac)3 always resulted in comparatively bigger particle formation (∼5 nm) while FeCl3 forms much smaller particles (∼1 nm) as confirmed by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM).

Single crystals of a novel organic-inorganic framework [Fe0.28V0.72OH0.8(NH4)0.2(C8H4O4)] · 0.53(C8H6O4), 1, have been prepared by hydrothermal synthesis in the presence of an oxidizing agent. The structure was solved by single crystal X-ray diffraction: space group Pnma, a = 17.6956 (19) Å, b = 6.8745 (7) Å, c = 11.9303(12) Å. The three dimensional framework is constructed from Fe/V-O chains that are cross-linked by 1,4-benzene dicarboxylate (BDC) anions forming large one-dimensional channels. As synthesized, the compound contains additional dicarboxylate groups occupying disordered positions in the channels that can be removed by heating. The chemical reactivity of 1 and its magnetic properties are reported. The new phase is closely related to analogous Cr (III) and V(III) phases recently reported by Férey and co-workers.

A methodology is described for protecting Carbon-Carbon fiber-matrix composite (C-C) components from oxidation for extended use in oxidizing ambients for lifetimes of the order of 10,000 hours, from room temperature to 650°C. This time-temperature profile is relevant to applications such as airborne heat exchangers. Weight changes of oxidation-protected, pitch-fiber based C-C coupons in flowing dry air at 650°C are presented. Two types of external protective approaches are compared: (a) multi-phase, borophosphate-based fluidizing overseal coatings applied directly to C-C, and (b) the same overseal coatings applied to CVD SiOxCy coated C-C. The latter, dual-coating approach provides an effective engineering solution for the above temperature-time profile and is particularly applicable to thin (0.1–3 mm thick), complex-shaped articles. The behavior of inert substrates (oxidized silicon) with the same overseal coatings is compared to the behavior of the C-C substrates. This approach can be applied with optional modifications to suit other environmental conditions, and other carbon-containing materials, such as carbon foams and C-SiC composites.

New approach to calculation of microstructure by means of the one-phase regions borders equations is proposed. Projections of all geometrical elements of phase diagram to the concentration simplex divide it to fields with unique crystallization schemes. All crystallization stages for the given concentration field are simulated and as a result the all elements of microstructure is designed and origin of every phase is shown.

Some perovskite –like Fe (Co) -containing and fluorite-like Bi –containing solid solutions considered as promising materials for high oxygen flux membranes application have been synthesized by the mechanochemical activation route. Structural/microstructural features of those systems characterized by TEM, XRD, IR, and Raman spectroscopy are compared with the data on their mixed conductivity and oxygen mobility. Some properties of nanocomposites comprised of those materials and such oxides as Fe2O3, BaTiO3, BaBiO3 etc are elucidated as well. Densification of those powdered samples by sintering in the 700–1400 K temperature range is accompanied by annealing of metastable phases generating “core-shell” nanocomposites with oxygen transport properties different from those of traditional materials.

By means of high pressure and high temperature we have prepared a new material similar to the classic YBa2Cu3O7 (Ybacuo) superconductor but having chromium in the so-called charge reservoir layer: CrSr2YCu2O8. It has been characterised by different techniques such as X-ray diffraction, TEM, ED, EDS, and magnetic susceptibility. The new material is isostructural with the Ru equivalent compound (RuSr2YCu2O8). An antiferromagnetic transition is observed on cooling below 130 K. The as prepared material is not superconducting down to 4 K.

Epitaxial nickel magnetic nanodots were obtained by pulsed laser deposition (PLD) technique on Si (100) substrate using epitaxial TiN film as the template. Characterization methods include: high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM) Z-contrast imaging, selected area electron diffraction (SAD), and X-ray diffraction (XRD) techniques. The results showed that as long as no coalescence between neighboring dots occurred, the dots are all single crystal. The predominant orientation relationship observed is Ni (100) // TiN (100) // Si (100), the so-called “cube-on-cube” orientation relationship. Other rotational orientation relationships, where the nickel crystal rotates an angle with respect to TiN (011) directions, were also observed. The dots are in faceted island shapes, bounded by (111) and (001) facets. The actual size of dots varies from a few nanometers to tens of nanometers, depending on the deposition time and temperature. The shape of a certain dot was found to be closely related to its epitaxial orientation. Effects of deposition temperature and template crystalline quality were studied. It was found that deposition temperature in a certain range does not have much influence on the epitaxial orientation of dots, while the crystalline quality of titanium nitride (the underlying template) is primarily responsible for the orientation variation. At the optimum condition, samples with a large fraction of cube-on-cube orientated nickel dots could be obtained in a rather wide temperature range (up to 250 °C), as evidenced by the strong reflections from both SAD and XRD. Samples containing more than one layer of nickel and titanium nitride matrix were also studied. The results showed that the degree of orientation perfection could be greatly improved by decreasing the size of dots.