Micro-Raman spectra of relaxor ferroelectric (RFE) in the (1-x)Pb(Zn1/3Nb2/3)O3 :xTiO3 solid solution series have been measured as a function of temperature (70-580K) and composition (x = 0.02, 0.085, and 0.11). Micro-Raman spectra have been recorded in frequency range of 30-1000cm-1 and have been analyzed for all the Raman modes observed in terms of integrated intensity, phonon width and phonon frequency position. No soft mode like behavior is observed in the measured frequency range. We do observe two multiple phase transitions at 67°C (340K) and 147°C (420K) for the composition ≤ 0.91PZN:09PT, but both the transitions are slightly diffused in nature.

The reaction of Bi4Ti3O12-x with lithium iodide under an atmosphere of iodine at 400°C was found to afford a novel intercalation compound Lil3Bi4Ti3O11. The brownish red bismuth titanate is monoclinic with the lattice parameters of a=5.7417(2), b=5.4016(2), c=36.787(1) Å and ß=88.93(1) deg. The pathway to the new intercalation compound is proposed on the basis of X-ray, XPS, SEM and compositional observations.

Thin films of indium zinc oxide so called IZO were prepared with pulsed laser deposition. It was found that the crystalline structure, the composition and the morphology of the films as well as the optical and electrical properties were quite sensitive to the deposition conditions namely to the temperature and oxygen pressure. The crystallinity of the ZnkIn2O3+k (k from 1 to 5) thin films increases as the substrate temperature increases. An average transmittance of 85 % in the visible region was obtained for any k values. Optical measurements show a continuous decrease of the band gap as the zinc amount increases. The highest conductivity reported is for the ZnIn2O4, thin films deposited at 300 °C (σ = 1.2 103 S/cm). Increasing the amount of Zn (i.e. k value) was found to result in a conductivity decrease. Finally, a good correlation between the electric mobility and the optical mobility is obtained.

Se1-xTeCuO3 (O≤x<1) phases crystallizing in perovskite structure with divalent copper at the octahedral sites have been characterized by x-ray diffraction, magnetization measurements and specific heat. The perovskites are unusual for possessing an extremely small A-site cation (Se4+, Te4+) with Cu-O-Cu bond angles in the range 120-130°. A continuous evolution in both structural and bulk properties is observed between the ferromagnetic (FM) ground state for x = 0 and an antiferromagnetic (AF) state for x = 1. The correlation of structural and magnetic properties allows the first determination of the Cu-O-Cu bond angle where the superexchange interaction sign changes, providing a quantitative realization of the Anderson-Goodenough-Kanemori rules for copper-oxide compounds.

Powder neutron diffraction and magnetization measurements are presented on the Co2Ru1-xMnxO4 system. In these materials the tetrahedral (A) sites are occupied by Co2+ (S = 3/2) ions, and the octahedral (B) sites are jointly occupied by Co3+ (low spin, S = 0), Ru3+ (low spin, S = 1/2), and Mn3+ (S = 2) ions. The measurements reveal that Co2RuO4 undergoes a spin-glass transition, Co2MnO4 is a collinear ferrimagnet, and that Co2Ru0.5Mn0.5O4 undergoes an unusual magnetic double transition. Triple-axis measurements indicate that the lower temperature transition in Co2Ru0.5Mn0.5O4 is characterized by the onset of diffuse scattering and the emergence of short-range order. The Co2Ru1-xMnxO4 series appears to be well-suited for studying the coexistence of long- and short-range magnetic order.

The synthesis, structural characterization, and magnetic properties of three strontium rhodium oxides Sr6Rh5O15, Sr4Rh3O9+δ, and Sr9Rh7O21+δ, is presented. While Sr6Rh5O15 is an example of a commensurate n = 1 member of the A3n+3A'nBn+3O6n+9 family of oxides, Sr4Rh3O9+δ, and Sr9Rh7O21+°, are examples of incommensurate n =2 and n = 3 members. Sr6Rh5O15 crystallizes in space group R32, a = 19.3197(2) Å, c = 13.0418(1) Å. The Sr6Rh5O15 structure is a superstructure of the Ba6Ni5O15 structure type. Sr4Rh3O9+δ, and Sr9Rh7P21+δ crystallize in the superspace group with lattice parameters of a = 9.6007(6), c1 = 2.6881(2), c2 = 4.2373(3), and a = 9.6127(6), c1 = 2.6769(2), c2 = 4.252(1), respectively. Their magnetic data are consistent with antiferromagnetic coupling between the chains leading to an ordered state at low temperature.

We present new detailed structural data versus temperature on the Nasicon structured material NbTi(PO4)3 obtained from powder neutron diffraction studies. This material shows a significant volume contraction over the range 20°C < T < 700°C. αa varies between –4.34 and -0.11 × 10-6°C-1 and αc between 0.08 and 3.07 × 10-6°C-1 over this range. This behaviour contrasts with the case of NaTi2(PO4)3 (NaTP) which shows a positive volume expansion. The difference in this behaviour can be explained by the presence of filled MI sites in NaTP which are vacant in the case of NbTP.

Compressible and polarizable ion models parametrized by ab initio calculations represent a promising technique for simulating challenging materials such as oxides. We present a new form of such a model in which the compression and polarization effects are coupled, and the anion-anion interaction is not fixed but dependent on the ion size and polarization. These two effects provide a more physically realistic description of a system, and significantly improve the predictive power of the method. Calculations on magnesium oxide show the elastic constants and other properties to be in good agreement with experiment. The new functional form is part of an ongoing project to develop an empirical model of zirconia, an important oxide for which a satisfactory model has yet to be determined.

Coordination and organometallic compounds containing bismuth, lanthanum or molybdenum are used as precursors for the preparation of unsupported or silica-supported Bi-based oxides. Bismuth (III) and lanthanum (III) polyaminocarboxylates, and more specifically homo- and heteropolymetallic complexes of triethylenetetraaminehexaacetic acid (H6ttha) are shown to constitute adequate precursors for the formation of mixed Bi2-xLaxO3 oxides at moderate temperatures. Silica-supported bismuth molybdates are obtained from impregnation or combined impregnation-deposition procedures involving Bi ß-diketonates, carboxylates or mixed acetate-Nmethylimidazole Bi complexes, in association with molybdenyl acetylacetonate or heteroleptic carbonyl-pyridine Mo complexes, either dissolved or dispersed in various organic solvents.

SnO2, Ru/SnO2 and Pt/SnO2 were prepared by sol-gel condensation method. Ru/SnO2 was also obtained by supporting the metal on SnO2 xerogel. The reactivity of these materials towards CO and air, studied by Electron Paramagnetic Resonance spectroscopy (EPR), suggests that the electron transfer processes at the oxide surface are favored by the presence of the metal, in the order Pt > Ru ion-exchanged > Ru-supported. A rationale was given for the differences and for the choice of a material suitable to high sensitivity gas sensors.

A simple yet versatile growth kinetic method (and device) has been developed in conjunction with present vapour phase preparation of layered MoO3 (orthorhombic). Using purified air at atmospheric pressure a sufficient amount of oxygen is warranted to ensure stoichiometry of grown metal oxide. The empirical vapour condensation rate of MoO3 is RE = 1.20×10-3ΔP2.07 over 642 to 660°C, where ΔP is the partial pressure difference of MoO3 between the source and condensed crystals. Based on observed crystal morphology and XRD result, a more precise MoO3 condensation kinetic model has been developed to explain the layer-by-layer growth of the layered structure. The driving force of the condensation growth is investigated with respect to the experimental set-up. On the basis of this work, it is suggested that the new kinetic approach is suitable for other volatile metal oxides or inorganic crystalline materials when an appropriate preparative atmosphere is selected.

This paper presents results from the oxidation of PuCl3 with two-thirds, one, and two equivalents of V2O5 and the oxidation of Pu° with two and three equivalents of V2O5. All of the PuCl3 reactions were successful in that little or no starting materials remained and the major plutonium reaction product was PuO2. There is no evidence that V is reduced to V(II) or V°. According to powder XRD analysis, the bottom layers of all three reactions are identical, the middle layers contain different phases, and phases in the top layer of the oxidation with one equivalent of V2O5 is contained in the top layer from the oxidation with two-thirds equivalent of V2O5. The Pu° oxidations are more complex than the PuCl3 oxidations. More unreacted Pu° remains in the reaction using three equivalents of V2O5 than the reaction using two equivalents of V2O5. The lack of predictability of these reactions may be a result of the source of Pu° used in our experiments. The presence of soluble Pu(III) and the relative absence of PuO2 in all the Pu° reactions suggests V2O5 does not oxidize Pu° to Pu(IV) under these conditions. Chlorine is detected in the off-gas of the Pu° oxidations, indicating the salt matrix participates in the reaction.

Single crystals of a new allotropic form of bismuth sesquioxide, Bi2O3 were prepared by low temperature hydrothermal reaction using hydrated sodium bismuth oxide, NaBiO3·nH2O, as a starting material. This bismuth oxide crystallized in the orthorhombic space group Pccn with a=12.732(2), b=4.955(2) and c=5.582(2)Å, z=4, and the R-factors were R=0.030 and Rw=0.030 for 1702 unique reflections. The crystal structure is built up by corner- and edge-sharing of irregular BiO5 polyhedra and the tunnel is running along the c-axis.

Five new compounds in the AxMTeO6 family were prepared and structurally characterized: Li2GeTeO6, Na2TiTeO6, Na2SnTeO6, and two forms of Na2GeTeO6. All compounds are layered structures based on various stacking arrangements of MTeO62- layers. Structural characterizations were carried out using a variety of tools, including Rietveld refinements of x-ray and neutron powder diffraction data, solid state MAS NMR and Raman spectroscopy. With the exception of Na2TiTeO6, the MTeO62-layers show a high degree of M4+/Te6+ order, but various degrees of disorder are present in the stacking of these layers. Disorder in the layer stacking favors the ilmenite structure, where both M4+ and Te6+ centered octahedra share faces with the AO6 octahedra. Coherent layer stacking favors an ordered variation of the α-TlSbO3 structure, where the AO6 octahedra preferentially share faces with either the MO6 or the TeO6 octahedra.

Influence of the precipitation conditions on the structure of Mg – Al layered double hydroxides (LDH) was investigated. XRD measurements demonstrate that species with hydrotalcite structure forms at high pH of reaction mixture (pH = 9 - 11), while at lower pH values (pH = 7 - 8) species with meixnerite structure arise. At the same time 27Al NMR studies of samples obtained at pH > 10 reveal the presence of tetrahedrally coordinated aluminum. XRD, NMR and IR data suggest that partial substitution of CO32- for Al(OH)4- in the interlayer space with subsequent formation of oxoaluminate bridges takes place at high pH. The optimal conditions for the preparation of intercalation-active materials were proposed.

Diopside (CaMgSi2O6) crystals were synthesized mainly by several methods from solution. Sol-gel methods and coprecipitation procedures were carried out using the metal chlorides, nitrates and TEOS as the starting materials. The diopsides obtained from the solutions, in which MgCl2 was used as one of the the starting reagents, showed the single phase diopside XRD patterns and fairly high mechnical strength. Sodium carbonate and iron nitrate were added to the starting solutions in order to examine the morphological effects of these extra elements. Resulted XRD patterns showed the small 2 θ shifts from the pure diopside patterns. The distribution maps of each elements were obtained by EPMA.

To confirm the bioactivity of these compounds, the end products pellets were immersed in the SBF. The apatite layer formations were inspected by XRD and SEM.

Lithium zirconate, which reacts with CO2 reversibly at temperatures over 500°C, is expected to find wider application than conventional CO2 absorbents, as the latter can be used only at room temperature. We examined the effect of potassium carbonate, which had usually been added to facilitate the formation of lithium zirconate in the past, on the kinetics of CO2 absorption reaction. The result shows that the CO2 absorption rate of lithium zirconate powder is extremely accelerated by the potassium carbonate additive. We conclude that this acceleration results from the formation of a eutectic carbonate composed of Li2CO3 and K2CO3.

Despite the relevance to a variety of materials applications, the electronic and bonding properties of spinel transition metal oxides are not well established. We report here the slow oxidation of CoO(100) to Co3O4, studied by photoemission (UPS and XPS), low energy electron diffraction (LEED) and high resolution electron energy loss spectroscopy (HREELS) with the aim of elucidating the valence band electronic structure of the Co3O4 spinel. The original Mott insulator picture of the parent CoO substrate has been revised in recent times, after careful analyses and extensive debate, to the more detailed charge-transfer insulator model which includes some admixture of oxygen 2p levels in the 3d-derived valence band. No equivalent band structure analysis has been performed on the spinel oxides, perhaps in part because of the greater complexity of the 56-atom unit cell with two different cation lattice sites and oxidation states. In this study, we determine the valence band structure of the spinel oxide and address the question of whether Co3O4 can be modeled as a charge-transfer insulator in analogy with its closely related rocksalt substrate.

Phase relations have been determined for the Bi-Ba oxide pseudobinary up to 50 cat % Ba in 1 atm of oxygen at 640°-1000°C. The low-temperature α-Bi2O3 polymorph does not dissolve appreciable BaO. All other phases in the system have significant ranges of solution. The δ-Bi2O3 polymorph, stable from 730°C to 825°C is an end-member of a face-centered cubic solid solution (FCCss) that dissolves up to 2.7 % Ba. Ba-saturated FCCss and Bi-saturated rhombohedral (ß) solid solution (6.3 % Ba) melt at a eutectic at 753 °C. Less Bi is needed to saturate the ß phase at lower temperatures so α-Bi2O3 coexists with a ß phase containing 11.5 % Ba at 646°C.

The amount of Ba required to saturate the ß phase depends less strongly on temperature. Ba-saturated ß phase contains 19 % Ba at 700°C. These ß materials are in equilibrium with an oxide near Bi3BaO5.5 that undergoes two polymorphic transformations: low-temperature cubic (<700°C); orthorhombic (700-730°C); high-temperature cubic (Cht). There is a eutectic between the ß and Cht, at 775±6°C. At T<700°C, 26.5 % Ba saturates the latter but it can take in up to 29.5 % Ba (at 812°C). At T<815°C the coexisting phase is BiBaO3. A tetragonal (T) phase forms by reaction of Ch, and BiBaO3 and has ~35% BaO at 815°C. The composition span of T widens as temperature increases. Cht, melts incongruently at 820°C to a liquid and T with 29.8 % Ba. Above that temperature the Bi-saturated and Ba-saturated T phases both become more Ba-rich as temperature is elevated. T melts incongruently to liquid and BiBaO3.

The δ-Bi2O3 and ß, both anion conductors, have structures based on that of fluorite. The other oxides have perovskite-like structures. Half of the Bi in BiBaO3 is pentavalent and half is trivalent. The other oxides appear to have all their Bi in the 3+ state.

Polycrystalline samples of Na1-xLnxNbO3 (Ln=La, Nd, Sm, Gd) were synthesized by solid-state reactions. Reduced niobates were obtained as single-phase perovskites for x=0.05 and 0.1 when Ln=La and Nd and x=0.05 when Ln=Sm. The Gd-substituted samples could not be prepared under the synthetic conditions studied. Compositional analysis of the products revealed a slight amount of sodium loss during synthesis. The structural parameters obtained from Rietveld analysis revealed an increase in unit-cell volume. All of the obtained samples showed semiconducting behavior. Similar semiconducting behavior was observed for the same x value, suggesting the weak influence of the different Ln species to the electrical properties.