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Damian Wojcieszak, Michał Mazur, Danuta Kaczmarek, Agata Poniedziałek and Małgorzata Osękowska

Abstract

The biological and photocatalytic activity of TiO2 and TiO2:Cu in relation to their structure, surface topography, wettability and optical properties of the thin films was investigated. Thin-film coatings were prepared by magnetron sputtering method in oxygen plasma with use of metallic targets (Ti and Ti-Cu). The results of structural studies revealed that addition of Cu into titania matrix (during the deposition process) resulted in obtaining of an amorphous film, while in case of undoped TiO2, presence of nanocrystalline anatase (with crystallites size of 20 nm) was found. Moreover, an addition of cooper had also an effect on surface diversification and decrease of its hydrophilicity. The roughness of TiO2:Cu film was 25 % lower (0.6 nm) as-compared to titania (0.8 nm). These modifications of TiO2:Cu had an impact on the decrease of its photocatalytic activity, probably as a result of the active surface area decrease. Antibacterial and antifungal properties of the thin films against bacteria (Enterococcus hirae, Staphylococcus aureus, Bacillus subtilis, Escherichia coli) and yeast (Candida albicans) were also examined. For the purpose of this work the method dedicated for the evaluation of antimicrobial properties of thin films was developed. It was revealed that Cu-additive has a positive impact on neutralization of microorganisms.

Open access

Damian Wojcieszak, Michal Mazur, Danuta Kaczmarek and Jaroslaw Domaradzki

Abstract

In this paper, structural and photocatalytic properties of TiO2 nanopowders doped with 1 at.% of cerium, cobalt, cooper and iron have been compared. Nanoparticles were synthesized by sol-gel technique and characterized by SEM, EDS and XRD methods. Moreover, their photocatalytic activity was determined based on decomposition of methyl orange. Results were compared with undoped powder. The structural investigations have revealed that all prepared nanopowders were nanocrystalline and had TiO2-anatase structure. The average size of crystallites was ca. 4 nm to 5 nm. The distribution of the dopant was homogenous in case of all manufactured powders. Moreover, for TiO2 doped with Co, Ce and Cu, aggregation effect was not as large as for TiO2:Fe. The results of photocatalytic decomposition showed that self-cleaning activity of all prepared nanopowders was higher as compared to undoped one. Due to the efficiency of these reactions (after 5 hours) nanopowders can be ordered as: TiO2:Co > TiO2:Ce > TiO2:Cu > TiO2:Fe > TiO2.

Open access

Damian Wojcieszak, Danuta Kaczmarek, Jarosław Domaradzki, Michał Mazur, Antoni W. Morawski, Magdalena Janus, Eugenius Prociów and Pietro Gemmellaro

In this work photocatalytic properties of TiO2 thin fi lms doped with 8.51 at. % of Nd were described. The self-cleaning phenomenon of thin fi lms was discussed together with the structural, optical and surface properties of prepared thin fi lms. Transparent coatings based on titanium dioxide were manufactured by high-energy reactive magnetron sputtering process. Incorporation of Nd during sputtering process results in amorphous behavior, without a signifi cant infl uence on transparency and colour as compared to the undoped TiO2-rutile matrix. Nevertheless, doping with neodymium doubles the photocatalytic activity of the matrix due to higher quantity of photo-generated charge carriers and more effi cient mechanism of energy transfer.

Open access

Damian Wojcieszak, Michał Mazur, Danuta Kaczmarek, Agata Poniedziałek, Piotr Domanowski, Bogumiła Szponar, Aleksandra Czajkowska and Andrzej Gamian

Abstract

In this work, the effect of titanium dioxide (TiO2) thin film microstructure on photocatalytic and biological activity was described. The films were prepared by low-pressure and high-energy magnetron sputtering processes. The structural investigations performed by X-ray diffraction revealed that the films from both the processes were nanocrystalline. It was found that TiO2 prepared by low-pressure process had the anatase structure with crystallites in size of 20 nm, while the film deposited in high-energy process had the rutile form with crystallites in size of 5 nm. The analysis of surface topography with the aid of optical profiler showed that all prepared films were homogenous and their roughness was lower than 1 nm. The wettability studies revealed hydrophilic nature of both films. The values of water contact angle obtained for anatase and rutile films were equal to 40° and 49°, respectively. Both types of the thin films were photocatalitycally active, but rutile exhibited higher decomposition rate as compared to anatase. During the photocatalytic reaction in the presence of TiO2-rutile film after 12 hours of UV-Vis irradiation 30 % of phenol was decomposed, whereas in case of TiO2-anatase it was only 10 %. Moreover, the influence of as-deposited coatings on the growth of selected microbes (Staphylococcus aureus, Escherichia coli, Candida albicans) was examined. It was found that the structural properties of TiO2 had an effect on biological activity of these films.

Open access

Tomasz Kotwica, Jaroslaw Domaradzki, Damian Wojcieszak, Andrzej Sikora, Malgorzata Kot and Dieter Schmeisser

Abstract

The paper presents results of investigations on surface properties of transparent semiconducting thin films based on (Ti-Cu)oxide system prepared using multi-magnetron sputtering system. The thin films were prepared using two programmed profiles of pulse width modulation coefficient, so called V- and U-shape profiles. The applied powering profiles allowed fabrication of thin films with gradient distribution of Ti and Cu elements over the thickness of deposited layers. Optical investigations allowed determination of transparency of prepared films that reached up to 60 % in the visible part of optical radiation, which makes them attractive for the transparent electronics domain. Surface properties investigations showed that the surface of mixed (Ti-Cu)oxides was sensitive to adsorption, in particular to carbon dioxide and water vapor. Soft etching with argon ions resulted in surface cleaning from residuals, however, deoxidation of Cu-oxide components was also observed.

Open access

Małgorzata Osękowska, Ewa Karuga-Kuźniewska, Damian Wojcieszak, Michał Mazur, Agata Poniedziałek, Danuta Kaczmarek, Maria Szymonowicz and Zbigniew Rybak

Abstract

In this work the physicochemical and biological properties of nanocrystalline TiO2 thin films were investigated. Thin films were prepared by magnetron sputtering method. Their properties were examined by X-ray diffraction, photoelectron spectroscopy, atomic force microscopy, optical transmission method and optical profiler. Moreover, surface wettability and scratch resistance were determined. It was found that as-deposited coatings were nanocrystalline and had TiO2-anatase structure, built from crystallites in size of 24 nm. The surface of the films was homogenous, composed of closely packed grains and hydrophilic. Due to nanocrystalline structure thin films exhibited good scratch resistance. The results were correlated to the biological activity (in vitro) of thin films. Morphological changes of mouse fibroblasts (L929 cell line) after contact with the surface of TiO2 films were evaluated with the use of a contrast-phase microscope, while their viability was tested by MTT colorimetric assay. The viability of cell line upon contact with the surface of nanocrystalline TiO2 film was comparable to the control sample. L929 cells had homogenous cytoplasm and were forming a confluent monofilm, while lysis and inhibition of cell growth was not observed. Moreover, the viability in contact with surface of examined films was high. This confirms non-cytotoxic effect of TiO2 film surface on mouse fibroblasts.

Open access

Damian Wojcieszak, Agata Poniedziałek, Michał Mazur, Jarosław Domaradzki, Danuta Kaczmarek and Jerzy Dora

Abstract

Rapid progress in thin-film coatings based on metals, which can be deposited on polymers, has been recently observed. In this work discussion on the properties of modified polymers and silver thin films deposited on polytetrafluoroethylene (PTFE) and polycarbonate (PC) substrates has been presented. Surface of these polymer substrates were exposed to argon plasma discharge. Additionally, silver thin films were deposited on their surface by electron beam evaporation method. The surfaces of the modified polymers were studied by different methods, i.e. topography, wettability and scratch resistance measurements were performed. The ageing effect of treated substrates was also discussed. It was shown that plasma modification of PTFE and PC substrates increased wettability of their surfaces. The value of water contact angle decreased of about 40 % and 25 % for PTFE and PC surface, respectively. The change of hydrophobic to hydrophilic properties was observed. Plasma modification of substrates improved adhesion between silver coating and polymer substrates. However, it did not influence wettability of Ag coating.

Open access

Damian Wojcieszak, Michał Mazur, Danuta Kaczmarek, Jerzy Morgiel, Agata Poniedziałek, Jarosław Domaradzki and Aleksandra Czeczot

Abstract

Titanium dioxide thin films doped with the same amount of neodymium were prepared using two different magnetron sputtering methods. Thin films of anatase structure were deposited with the aid of Low Pressure Hot Target Magnetron Sputtering, while rutile coatings were manufactured using High Energy Reactive Magnetron Sputtering process. The thin films composition was determined by energy dispersive spectroscopy and the amount of the dopant was equal to 1 at. %. Structural properties were evaluated using transmission electron microscopy and revealed that anatase films had fibrous structure, while rutile had densely packed columnar structure. Atomic force microscopy investigations showed that the surface of both films was homogenous and consisted of nanocrystalline grains. Photocatalytic activity was assessed based on the phenol decomposition. Results showed that both thin films were photocatalytically active, however coating with anatase phase decomposed higher amount of phenol. The transparency of both thin films was high and equal to ca. 80% in the visible wavelength range. The photoluminescence intensity was much higher in case of the coating with rutile structure.

Open access

Michał Mazur, Danuta Kaczmarek, Jarosław Domaradzki, Damian Wojcieszak, Piotr Mazur and Eugeniusz Prociow

Abstract

Thin films were deposited using modified, high energy magnetron sputtering method from Ti-Nd mosaic targets. The amount of neodymium dopant incorporated into two sets of thin films was estimated to be 0.8 and 8.5 at.%, by means of energy dispersive spectroscopy. On the basis of x-ray diffraction method, the type of crystalline structure and crystallites size were evaluated directly after the deposition process and after additional post-process annealing at 800 °C temperature. The influence of annealing on the surface properties was evaluated with the aid of atomic force microscopy. Uniformity of the dopant distribution in titanium dioxide matrix was examined with the aid of secondary ion mass spectroscopy. Additionally, using atomic force microscope, diversification and roughness of the surface was determined. Chemical bonds energy at the surface of TiO2:Nd thin films was investigated by x-ray photoelectron spectroscopy method. Wettability measurements were performed to determine contact angles, critical surface tensions and surface free energy of prepared coatings. On the basis of performed investigations it was found, that both factors, the amount of neodymium dopant and the post-process annealing, fundamentally influenced the physicochemical properties of prepared thin films.

Open access

Michal Mazur, Danuta Kaczmarek, Eugeniusz Prociow, Jaroslaw Domaradzki, Damian Wojcieszak and Jakub Bocheński

Abstract

In this work the results of investigations of the titanium-niobium oxides thin films have been reported. The thin films were manufactured with the aid of a modified reactive magnetron sputtering process. The aim of the research was the analysis of structural, optical and electrical properties of the deposited thin films. Additionally, the influence of post-process annealing on the properties of studied coatings has been presented. The as-deposited coatings were amorphous, while annealing at 873 K caused a structural change to the mixture of TiO2 anatase-rutile phases. The prepared thin films exhibited good transparency with transmission level of ca. 50 % and low resistivity varying from 2 Ωcm to 5×10−2 Ωcm, depending on the time and temperature of annealing. What is worth to emphasize, the sign of Seebeck coefficient changed after the annealing process from the electron to hole type electrical conduction.