This thesis is focused on studies of substituted Hg-based superconducting copper oxides ((Hg1-xMx)Ba2Can-1CunO2n+2+δ). These compounds are promising objects of investigation, not only from a fundamental point of view but also because of their high values of superconducting transition temperature (Tc) and irreversibility field (Hirr). The first part of the thesis is devoted to optimization of the synthesis procedure for Hg-based cuprates. The influence of different parameters (T, t, p(Hg), p(O2)) on the synthesis of these compounds in sealed silica tubes was studied. Optimal conditions yielded samples containing up to 95% of HgBa2Ca2Cu3O8+δ (Hg-1223). The formation of solid solutions with the formula (Hg1-xCux)Ba2Ca2Cu3O8+δ (where x <= 0.5) was also established. Another technique was developed, using LiF as a flux, for synthesis of samples containing up to 90% of the HgBa2CaCu2O6+δ (Hg-1212) phase. The second part concerns synthesis and studies of oxyfluorides using Hg-1212 and Hg-1223 as starting materials together with XeF2 as a fluorinating agent. It was found that oxyfluorides of both phases have a parabolic dependence of Tc vs. a parameter as well as enhanced Tc values (ΔT ≈ 3-4 K) in comparison with optimally doped non-fluorinated analogues. The crystal structure of Hg-1223 oxyfluoride was studied by X-ray powder and neutron diffraction methods. It is suggested that chemical modification of the crystal structure leads to a decrease in Cu-O distance without noticeable change in Cu-O-Cu angle (in the (CuO2) layers), which may be the significant factors influencing this Tc increase. Hg-1223 oxyfluoride was also studied under high pressure for first time. It was found that this compound has a record-high Tc value (≈ 166 K) at P ≈ 23 GPa. The last part describes the investigation of substituted Hg-based superconductors in the series (Hg0.9M0.1)Ba2CuO4+δ {(Hg,M)-1201}, where M = Tl, Pb, W, Mo, Nb and V. A comprehensive study of these compounds by various methods (X-ray powder diffraction, EDX, IR-, EXAFS- and XANES -spectroscopy) indicated that the change of charge carrier doping level is a crucial factor determining the irreversibility line. (Hg0.9Mo0.1)Ba2CuO4+δ showed the most improved irreversibility line position among the (Hg,M)-1201 compounds studied in this series.

This thesis is based on a study of five distinct intermetallic systems with the aim of expanding the general knowledge of aperiodically modulated crystal structures. Families of compounds that contain a variety of superstructures together with incommensurately modulated structures have been investigated mainly by means of single crystal X-ray diffraction and higher dimensional structure models. A uniform (3+1)-dimensional structure for Bi-Se phases was developed with the composition as a single variable. The structure description is based on a cubic NaCl type structure with homoatomic layer stackings. It is shown by computational modelling that the formation energies of bismuth selenides with more than 40 at. % Bi are close to zero, a result that supports the idea of a continuous series of stackings corresponding to an ordered solid solution of Bi in Bi2Se3. The Nowotny chimney-ladder structures are described with a (3+1)-dimensional composite structure, valid for all such compounds regardless of the included elements, the composition or the valence electron concentration. A new member is added to this family by the ZrBi1.62 compound. The modulation is believed to arise as a secondary effect of the criteria of a fixed electron count. A symmetry analysis is presented for the RE1+ε(MB)4 (RE = rare earth elements, M = iron metal elements) family of compounds and a uniform (3+1)-dimensional composite structure description has been developed. The modulation may be due to the presence of unusually short contacts between the RE channel atoms, giving rise to a rotational modulation of the (MB)4 tetraederstern chains. A (3+1)-dimensional incommensurate structure has been determined for the novel δ1 – CoZn compound. The structure displays a unique assembly of fused icosahedra and the modulation is induced by geometric strain. The structure of the K(PtSi)4 compound was re-determined. Despite a close kinship with the RE1+ε(MB)4 compounds, this structure is not modulated.

This thesis is based upon synthesis and structure determination of new transition metal oxo-halide compounds, which includes p-element cations that have a stereochemically active lone pair. A synthesis concept has been developed, which uses several different structural features to increase the possibility to yield a low-dimensional arrangement of transition metal cations. A total of 17 new compounds has been synthesised and their structures have been determined via single-crystal X-ray diffraction. The halides and the stereochemically active lone-pairs will typically act as terminating species segregating into regions of non-bonding volumes, which may take the form of 2D layers, 1D channels or Euclidean spheres. The transition metals that have been used for this work are copper, cobalt and iron. The Hard-Soft-Acid-Base principle has been utilized to match strong Lewis acids to strong Lewis bases and weak acids to weak bases. All compounds show tendencies towards low-dimensionality; they all have sheets of transition metal cations arranged into layers, where the layers most often are connected via weak dispersion forces.

Nano-powders of BaTiO3, SrTiO3, Ba0.6Sr0.4TiO3, a mixture of the composition (BaTiO3)0.6(SrTiO3)0.4 with particle sizes in the range of 60 to 80 nm, and Bi4Ti3O12 with an average particle size of 100 nm were consolidated by spark plasma sintering (SPS). The kinetics of reaction, densification and grain growth were studied. An experimental procedure is outlined that allows the determination of a “kinetic window” within which dense nano-sized compacts can be prepared. It is shown that the sintering behaviour of the five powders varies somewhat, but is generally speaking fairly similar. However, the types of grain growth behaviour of these powders are quite different, exemplified by the observation that the kinetic window for the (BaTiO3)0.6(SrTiO3)0.4 mixture is 125 oC, ~75 oC for Bi4Ti3O12, ~25oC for BaTiO3 and SrTiO3, while it is hard to observe an apparent kinetic window for obtaining nano-sized compacts of Ba0.6Sr0.4TiO3. During the densification of the (BaTiO3)0.6(SrTiO3)0.4 mixture the reaction 0.6BaTiO3+0.4SrTiO3 → Ba0.6Sr0.4TiO3 takes place, and this reaction is suggested to have a self-pinning effect on the grain growth, which in turn explains why this powder has a large kinetic window. Notably, SPS offers a unique opportunity to more preciously investigate and monitor the sintering kinetics of nano-powders, and it allows preparation of ceramics with tailored microstructures. The dielectric properties of selected samples of (Ba, Sr)TiO3 ceramics have been studied. The results are correlated with the microstructural features of these samples, e.g. to the grain sizes present in the compacts. The ceramic with nano-sized microstructure exhibits a diffuse transition in permittivity and reduced dielectric losses in the vicinity of the Curie temperature, whereas the more coarse-grained compacts exhibit normal dielectric properties in the ferroelectric region. The morphology evolution, with increasing sintering temperature, of bismuth layer-structured ferroelectric ceramics such as Bi4Ti3O12 (BIT) and CaBi2Nb2O9 (CBNO) was investigated. The subsequent isothermal sintering experiments revealed that the nano-sized particles of the BIT precursor powder grew into elongated plate-like grains within a few minutes, via a dynamic ripening mechanism. A new processing strategy for obtaining highly textured ceramics is described. It is based on a directional dynamic ripening mechanism induced by superplastic deformation. The new strategy makes it possible to produce a textured microstructure within minutes, and it allows production of textured ferroelectric ceramics with tailored morphology and improved physical properties. The ferroelectric, dielectric, and piezoelectric properties of the textured bismuth layer-structured ferroelectric ceramics have been studied, and it was revealed that all textured samples exhibited anisotropic properties and improved performance. The highly textured Bi4Ti3O12 ceramic exhibited ferroelectric properties equal to or better than those of corresponding single crystals, and much better than those previously reported for grain-orientated Bi4Ti3O12 ceramics. Textured CaBi2Nb2O9 ceramics exhibited a very high Curie temperature, d33-values nearly three times larger than those of conventionally sintered materials, and a high thermal depoling temperature indicating that it is a very promising material for high-temperature piezoelectric applications.

Complex transition metals oxyhalides containing a lone pair element, such as tellurium (IV), form an attractive research field because there is a high probability of finding new low-dimensionally arranged compounds and, particularly, a low-dimensionally arranged transition metals substructures, leading to interesting physical properties. Tellurium (IV) can drive the formation of many unusual structures because of its stereochemically active lone pair electrons, E. It commonly takes a coordination of three or four oxygen atoms to form either a TeO3E square pyramid or a TeO3+1E trigonal bipyramid. These lone pairs are very important players involved in lowering the dimensionality of crystal structures. Previous studies in transition metal tellurium (IV) oxohalide quarternary systems revealed a family of compounds, many of which exhibit interesting properties e.g. magnetic frustration. The unique point of this thesis is to employ alkaline earth elements (AE) to augment this ability of lone pair elements to lower the dimensionality of the transition metal arrangements. By this double usage of “chemical scissors” (a lone pair element used in conjunction with alkaline earth elements) we obtained new types of low-dimensionally arranged compounds. This thesis is focused on the syntheses and characterization of a series of compounds in the pentanary (five components) system AE-TeIV-TM-O-X (AE=alkaline earth metal, TM=transition metal and X=halogen), in which nine new compounds were found. The crystal structures of each of these compounds were determined by the single crystal X-ray diffraction data.

Diamond and cubic boron nitride surfaces have extreme properties that can be exploited in novel tribological, electrochemical and electronic applications. Normally insulating diamond surfaces can exhibit high surface conductivities due to hydrogen termination and the nature of the surrounding atmosphere. Successful growth of cubic boron nitride thin films is hindered when harsh synthesis methods are used. Three significant surface-related properties are addressed in this thesis using computational methods: (1) the structure, energy stability and reactivity of clean and differently terminated diamond surfaces, (2) the high surface conductivity of diamond, and (3) the adsorption-induced stability, reactivity and reconstruction of the cubic boron nitride (100) surface. Density Functional Theory (DFT) has been used at the GGA level under periodic boundary conditions to simulate the diamond and cubic boron nitride surfaces. The diamond surface structures are shown to be insensitive to hydrogen desorption. Oxygen atoms bind in different positions and with different bond strengths. Hydroxyl groups experience both attractive hydrogen bonding and steric repulsions within the adsorbed species. The reconstruction of diamond (111)-1x1 is strongly dependent on the species adsorbed onto the surface. Electron transfer was observed from a diamond surface into a water-based adlayer, yielding a p-type doped surface, depending on the nature of the surface and the adlayer. The cubic boron nitride (100)-1x1 surface was shown to reconstruct into a 2x1 configuration on both the boron- and nitrogen-rich side through the formation of B-B bonds, as well as N–N dimer-induced surface relaxation. Hydrogen stabilized the (100)-1x1 surface, but the partial removal of hydrogen yielded non-reactive dimer formation on the surface.

Thin films of cobalt oxide, iron oxide and niobium oxide, and nanostructured thin films of iron oxide, titanium oxide and multilayered iron oxide/titanium oxide have been deposited by Atomic Layer Deposition (ALD). The metal oxides were grown using the precursor combinations CoI2/O2, Fe(Cp)2/O2, NbI5/O2 and TiI4/H2O. The samples were analysed primarily with respect to phase content, morphology and growth characteristics. Thin films deposited on Si (100) were found to be amorphous or polycrystalline, depending on deposition temperature and the oxide deposited; cobalt oxide was also deposited on MgO (100), where it was found to grow epitaxially with orientation (001)[100]Co3O4||(001)[100]MgO. As expected, the polycrystalline films were rougher than the amorphous or the epitaxial films. The deposition processes showed properties characteristic of self-limiting ALD growth; all processes were found to have a deposition temperature independent growth region. The deposited films contained zero or only small amounts of precursor residues. The nanostructured films were grown using anodic aluminium oxide (AAO) or carbon nanosheets as templates. Nanotubes could be manufactured by depositing a thin film which covers the pore walls of the AAO template uniformly; free-standing nanotubes retaining the structure of the template could be fabricated by removing the template. Multilayered nanotubes could be obtained by depositing multiple layers of titanium dioxide and iron oxide in the pores of the AAO template. Carbon nanosheets were used to make titanium dioxide nanosheets with a conducting graphite backbone. The nucleation of the deposited titanium dioxide could be controlled by acid treatment of the carbon nanosheets.

Nitrogen rich glasses in the systems Ca-Si-O-N, Sr-Si-O-N and AE-Ca-Si-O-N (AE = Mg, Sr and Ba) have been prepared using a novel glass-synthesis route. The limits of the glass forming regions in the Ca and Sr systems and substitution limits in the AE-Ca-Si-O-N systems have been determined and physical properties of the glasses measured. Transparent glasses were obtained for a few specific compositions in the Ca-Si-O-N and Mg-Ca-Si-O-N systems. All other glasses were found to be translucent gray to opaque black, with the coloration of the glasses depending on the modifier. Small inclusions of Ca/Sr silicides and, in much smaller amounts, elemental Si are believed to be responsible for their poor transparency. A large glass forming region was found for the Ca-Si-O-N system, with glasses retaining up to 58 e/o N and 42 e/o Ca. In comparison, a more narrow glass forming region was found for the corresponding Sr system, with glasses retaining up to 45 e/o N and 39 e/o Sr. The glass formation was found to depend on reaction kinetics and precursors used. A strong exothermic reaction was observed at temperatures 650–1000oC, providing improved conditions for reaction kinetics upon further heating. Physical property measurements for the Ca and Sr glasses showed that glass transition and crystallization temperatures, viscosity, hardness, Young’s modulus and shear modulus depend strongly on the nitrogen content and that these properties increase approximately linearly with increasing nitrogen content. Glass density and refractive index are also dependent on the modifier element and content, in particular for the Sr glasses. Glasses AE-Ca-Si-O-N, with approximately constant (Ca/AE): Si:O:N ratios, showed that mixed modifier glass properties, such as density, molar volume, glass transition temperature, hardness, refractive index can be related to the effective cation field strength of the modifiers.

Demands for high energy-density batteries have sharpened with the increased use of portable electronic devices, as has the focus global warming is now placing on the need for electric and electric-hybrid vehicles. Li-ion battery technology is superior to other rechargeable battery technologies in both energy- and power-density. A remaining challenge, however, is to find an alternative candidate to graphite as the commercial anode. Several metals can store more lithium than graphite, e.g., Al, Sn, Si and Sb. The main problem is the large volume changes that these metals undergo during the lithiation process, leading to degradation and pulverization of the anode with resulting limitations in cycle-life. The Li-ion battery is studied in this thesis with the goal of better understanding the critical parameters determining high and stable electrochemical performance when using a metal or a metal-alloy anode. Various antimony-containing systems will be presented. These represent different routes to circumvent the problems caused by volume change. Sb-compounds exhibit a high lithium storage capability. At most, three Li-ions can be stored per Sb atom, leading to a theoretical gravimetric capacity of 660 mAh/g. Model systems with stepwise increasing complexity have been designed to better understand the factors influencing lithium insertion/extraction. It is demonstrated that the microstructure of the anode material is crucial to stable cycling performance and high reversibility. The relative importance of the various factors controlling stability, such as particle-size, oxide content and morphology, varies strongly with the type of system studied. The cycling performance of pure Sb is improved dramatically by incorporating a second component, Sb2O3. With a critical oxide concentration of ~25%, a stable capacity close to the theoretical value of 770 mAh/g is obtained for over 50 cycles. Cu2Sb shows stable cycling performance in the absence of oxide. Cu9Sb2 has been presented for the first time as an anode material in a Li-ion battery context. Studies of the Solid Electrolyte Interphase (SEI) formed on AlSb composite electrodes show an SEI layer thinner than graphite, and with a clearly dynamic character.

This dissertation has been focused on the synthesis and characterization of novel functionalized silica mesoporous crystals by using cationic surfactant and co–structure directing agents (CSDA), the central concept of the synthesis method is to build proper organic/inorganic interactions by introducing CSDA into the synthesis system. By using cationic surfactant as template and anionic CSDA, carboxylic group functionalized mesoporous silicas were successfully synthesized. Well ordered 2D p6mm, cubic Fm-3m, mixture of CCP (Fm-3m) and HCP (P63/mmc), and cubic Fd-3m with uniform carboxylic group distribution have been obtained. Besides, we have investigated the Fm-3m/Fd-3m type intergrowth and new type defects observed in the Fd-3m structure using transmission electron microscopy (TEM) and proposed a “polyhedron packing” model. New amphoteric, inorganic amino acid with highly ordered mesopores were synthesized. Uniform distribution of acid and base organic groups on the mesopore surfaces were formed by interactions between the counter charged surfactant head groups and ionic parts of CSDAs. It has been demonstrated that organic (–NH2 and –COOH) pairs incorporated in the mesopore walls behave as natural amino acids, collectively exhibiting an isoelectric point of ~6.0. Moreover, we have demonstrated that the inorganic amino acid is an efficient catalyst for the reaction between aldehydes and carbon nucleophiles.