The presented work encompasses the subject of the studies and the results obtained over the last years by the research workers of the Department of Inorganic Chemistry. They include mainly the studies on the reactivity of metal oxides, searching for new phases in binary and ternary systems of metal oxides as well as describing phase relations establishing in such systems. They also encompass works on the extensive characteristics of physico-chemical properties of the newly obtained compounds.

Pseudomonas aeruginosa is a bacterium producing industrially utile metabolites, such as rhamnolipids, biopolymers, and pigments. Pyocyanin, the most studied example of pigments, is a virulence factor that also shows the potential for application in, e.g., agriculture, anticancer therapy, and energy production. Therefore, potential inhibitors and stimulants of pyocyanin production by P. aeruginosa should be studied, and nanomaterials may cause both effects. The study aimed to examine the influence of zinc oxide and multi-walled carbon nanotubes (pristine or dispersed with alginic acid) on pyocyanin production by P. aeruginosa. First, the influence of different concentrations of nanomaterials (500.00–0.06 µg/mL) on culture optical density and biofilm formation was studied. These results helped select concentrations for further tests, i.e., growth curves and fluorescence measurements. Pyocyanin production was assessed by the chloroform–hydrochloric acid method. SEM analysis was conducted to assess the influence of nanomaterials on the cell's integrity and biofilm structure. Pristine multi-walled carbon nanotubes exhibited a stimulative effect on pigment production when applied in high concentrations (500.00 µg/mL), while dispersed material enhanced the production in lowered dosages (125.00 µg/mL). On the other hand, high concentrations of zinc oxide inhibited pyocyanin production, while minor increased bioproduct production. The research indicates the potential to use nanomaterials as the modulators of pyocyanin production and other metabolites.

It has been demonstrated that apart from the known compounds YbVO₄ and Yb₈V₂O₁₇, a substitutive solid solution is also formed in the binary oxide system V₂O₅–Yb₂O₃. This solid solution is characterized by limited solubility of vanadium(V) oxide in the crystal lattice of ytterbium oxide, and its general formula is Yb_2−5x□_2xV_3xO₃, where 0.00 < x < 0.1667. The new solid solution was obtained from the mixtures of V₂O₅ and Yb₂O₃ oxides, containing vanadium(V) oxide in the amounts not exceeding 30 mol%, by high-energy ball milling in a planetary ball mill. The solid solution obtained was characterized using the methods XRD, DTA-TG, SEM, IR and UV–Vis-DR. It was found to crystallize in cubic system and to show a structure of Yb₂O₃. This solid solution was stable in air atmosphere at least up to ~ 800 °C, and the temperature of its decomposition decreased with increasing x, so with increasing degree of Yb³⁺ replacement with V⁵⁺ in the crystal lattice of Yb₂O₃. The energy gap estimated for this solid solution varied from ~ 2.5 eV for x = 0.0322 to ~ 2.6 eV for x = 0.1176, which means that this new solid solution is a semiconductor.

New substitutional limited solid solution of the formula Yb_8−xY_xV₂O₁₇ and 0 < x < 4.0 was synthesised by the solid-state reaction from the mixtures of the compounds Yb₈V₂O₁₇ and Y₈V₂O₁₇. The monophasic samples containing Yb_8−xY_xV₂O₁₇ were characterised by powder XRD, DTA, IR, UV–Vis–DRS and SEM methods. The influence of the degree of Y³⁺ ion incorporation in the crystal lattice of Yb₈V₂O₁₇ replacing Yb³⁺ ions, on the thermal stability, unit cell volume, band gap energies as well as on the position of the IR absorption bands in the spectrum of Yb_8−xY_xV₂O₁₇ was determined. The morphology of Yb₈V₂O₁₇ and solid solution was analysed.