Anna Wolska

This study investigated the electrochemical protection provided by amorphous hafnium thin films deposited on austenitic stainless steel by atomic layer deposition technology that guarantees control over the physicochemical properties of deposited coatings and processes repeatability. Furthermore, ALD enables conformal coating of three-dimensional shapes. The corrosion resistance of these coatings was evaluated under conditions simulating physiological environments, using potentiodynamic polarization and electrochemical impedance spectroscopy. Furthermore, X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy were employed to analyze the chemical stability, surface condition, and morphology of the films prior to and following electrochemical testing. Potentiodynamic polarization tests demonstrated that uncoated SS316L provided insufficient corrosion resistivity, whereas samples coated with ALD-grown hafnium dioxide thin films possessed barrier properties, exhibited a pronounced passive region and a reduction in anodic and cathodic current densities by up to three orders of magnitude. Electrochemical impedance spectroscopy results further verified the development of a compact, highly resistive dielectric interface. X-ray photoelectron spectroscopy analysis demonstrated that the films exhibited chemical stability following corrosion. SEM images showed that after electrochemical tests on stainless steel, significant surface degradation was observed, whereas the hafnium dioxide-coated surfaces remained unchanged. The findings suggested that films with a thickness of ≈100 nm act as effective barriers to corrosive ions. These results highlight the potential of ALD-deposited amorphous hafnium dioxide thin films as protective coatings against corrosion and present promising prospects for future biomedical applications.

The presence of luminescence centers, formed as a result of coating GaN nanowires with HfO _x shells, has been demonstrated using cathodoluminescence spectroscopy and mapping, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy.

Structural behavior of Ca ₁₀ Ni _0.5 (VO ₄ ) ₇ under low temperature and high pressure conditions: lattice parameters, thermal expansion, and compressibility analysis.

A sonochemical synthesis of SnS₂ quantum dots using acetone as a solvent is investigated. Two different tin sources (SnCl₂∙2H₂O or SnCl₄∙5H₂O) as well as two different sulfur sources (thioacetamide or Na₂S₂O₃) were applied. The sonication time was also varied between 60 and 120 min. Resulting products of syntheses were characterized with the following techniques: powder X-ray diffraction, electron microscopy (SEM and HR-TEM), Raman and FT-IR spectroscopies, the Tauc method, and X-ray photoelectron spectroscopy. Obtained SnS₂ nanostructures were in the form of quantum dots in the case of synthesis lasting 60 min (size of crystallites in the range of 3.5–7 nm) and in the form of elongated nanorods of length ca. 25–30 nm and width of 5–6 nm in the case of synthesis lasting 120 min. XPS analyses revealed that the surface of the obtained products contained a significant amount of tin at the second oxidation state (i.e., SnS). The quantum dots produced in the synthesis lasting 60 min showed a value of energy bandgap of 2.7 eV indicating potential applications in photocatalysis.

A sonochemical synthesis of SnS2 quantum dots using acetone as a solvent is investigated. Two different tin sources (SnCl2∙2H2O or SnCl4∙5H2O) as well as two different sulphur sources (thioacetamide or Na2S2O3) were applied. The sonication time was also varied between 60 and 120 minutes. Resulting products of syntheses were characterized with the following techniques: powder X-ray diffraction, electron microscopy (SEM and HR-TEM), Raman and FT-IR spectroscopies, the Tauc method, and X-ray photoelectron spectroscopy. Obtained SnS2 nanostructures were in the form of quantum dots in the case of synthesis lasting 60 minutes (size of crystallites in the range of 3.5 – 7 nm) and in the form of elongated nanorods of length c.a. 25-30 nm and width of 5-6 nm in the case of synthesis lasting 120 minutes. XPS analyses revealed that the surface of the obtained products contained significant amount of tin at the second oxidation state (i. e. SnS). The quantum dots produced in the synthesis lasting 60 minutes showed value of energy bandgap of 2.7 eV indicating potential applications in photocatalysis.

Two new Ag(I) complexes with coumaric carboxylic acid derivatives have been synthesized. Structural studies of these noncrystalline complexes have been performed using a methodology that combines laboratory and synchrotron techniques, supported by density functional theory calculations. The arrangement of ligands around the Ag(I) cation has been refined using infrared, extended X-ray absorption fine structure, and X-ray absorption near edge structure spectroscopies. Different coordination modes of carboxylate ligands are observed for the studied compounds. Carboxylate bridges are characteristic for the Ag(I) complex with 4-oxo-4H-1-benzopyran-2-carboxylic acid (1), while a bidentate chelating motif was found for the complex with 2-oxo-2H-1-benzopyran-3-carboxylic acid (2). Additionally, the carbonyl oxygen atom of the coumarin ring coordinates to the silver cation in complex 2, while it is inactive in complex 1. Antimicrobial evaluation has been performed for both compounds. The complexes show activity against selected bacteria as well as Candida yeast. This activity is slightly lower for bacteria and the same or higher for Candida in relation to the reference substances: ciprofloxacin or fluconazole.

This paper presents an investigation into the influence of repeating cycles of hydrothermal growth processes and rapid thermal annealing (HT+RTA) on the properties of CuO thin films. An innovative hydrothermal method ensures homogeneous single-phase films initially. However, their electrical instability and susceptibility to cracking under the influence of temperature have posed a challenge to their utilization in electronic devices. To address this limitation, the HT+RTA procedure has been developed, which effectively eliminated the issue. Comprehensive surface analysis confirmed the procedure’s ability to yield continuous films in which the content of organic compounds responsible for the formation of cracks significantly decreases. Structural analysis underscored the achieved improvements in the crystalline quality of the films. The implementation of the HT+RTA procedure significantly enhances the potential of CuO films for electronic applications. Key findings from Kelvin probe force microscopy analysis demonstrate the possibility of modulating the work function of the material. In addition, scanning capacitance microscopy measurements provided information on the changes in the local carrier concentration with each repetition. These studies indicate the increased usefulness of CuO thin films obtained from the HT+RTA procedure, which expands the possibilities of their applications in electronic devices.