PL240989B1 - Method of preparation of a silver and nitrogen modified titanium dioxide coating and a coating obtained thereby - Google Patents

Description

PL 240 989 B1

Description of the invention

The subject of the invention is a method of producing a transparent coating of titanium dioxide modified with silver and nitrogen, and the coating produced by this method. The transparent coating, due to its antibacterial properties, is intended especially for applying tools, apparatus, etc. on ceramic substrates, used in hospitals and other health care facilities, which in turn should contribute to reducing hospital infections - a serious problem faced by health service.

From the publications of Adolfo A., Mosquera, Jose M. Albella, Violeta Navarro, Debabrata Bhattacharyya & Jose L. Endrino, Effect of silver on the chase transition and wettability of titanium oxide films, (Scientific Reports, 2016), the antibacterial properties of non-toxic, transparent titanium dioxide coatings activated by UV radiation, while a nanocomposite based on titanium dioxide with Ag nanoparticles shows photocatalytic properties, also activated by visible radiation.

The antibacterial effect of the silver and nitrogen modified titanium dioxide coating is based on the formation of hydroxyl radicals and reactive oxygen species on the surface in the process of photocatalysis activated with UV and Vis radiation and through the Ag + ion release mechanism. From the publication of Lei Miao et al., Microstructure and bactericidal ability of photocatalytic TO2 thin films prepared by rf helicon magnetron sputtering, (Applied Surface Science, 2004, 238, 125-131) and JamunaThevi K. et al. Quantification of silver ion release, in vitro cytotoxicity and antibacterial properties of nanostuctured Ag doped TiO2 coatings on stainless steel deposited by RF magnetron sputtering, (Vacuum, 2011, 86, 235-241), it is known that the photocatalytic activity of titanium dioxide depends on its polymorphic form. The anatase phase is desirable because of the greater degree of surface hydroxylation than the rutile phase. However, Navabpour P. et al., In The effect of process parameters on the structure, photocatalytic and self-cleaning properties of TO2 and Ag-TiO2 coatings deposited using reactive magnetron sputtering (Thin Solid Films, 571, 2014, 75-83) found that the TiO2: Ag coating with the microstructure consisting of the rutile phase showed no antibacterial potential, however the coating with the mixed structure - anatase and rutile phases eliminated bacteria within 12 hours without the need for light activation. The antibacterial properties of the Ti2.8O4N phase obtained by chemical vapor deposition against E. coli bacteria are confirmed by the studies of Zoie A. et al., Antimicrobial Activity in Thin Films of Pseudobrookite-Structured Titanium Oxynitride under UV Irradiation Observed for Escherichia coli (Chemical Vapor Deposition, DOI: 10.1002 / cvde.200904285, 2010). In turn, the antibacterial properties of titanium dioxide coatings with the addition of Ag but produced by magnetron sputtering are confirmed by Jamuna-Thevi K. et al., Quantification of silver ion release, in vitro cytotoxicity and antibacterial properties of nanostuctured Ag doped TO2 coatings on stainless steel deposited by RF magnetron sputtering (Vacuum, 2011, 86, 235-241) and Hrkac T. et al., Huge increase of therapeutic window at a bioactive silver / titania nanocomposite coating surface compared to solution (Materials Science Engineering C, 2013, 33, 2367-75 ), and the antibacterial properties of nitrogen-modified titanium dioxide coatings are confirmed by Morikawa T. et al., Visible-light photocatalyst - nitrogen-doped titanium dioxide (Reascarch Report, R&D Review of Toyota CRDL, 2015, 40, 3). In turn, Rtimi S. et al., TiON and TiON-Ag sputtered surfaces leading to bacterial inactivation under indoor actinic light (J Photochem Photobiol A, 2013, 256, 52-63) investigated the antibacterial effect of TiON and TiON: Ag coatings produced by spraying magnetron, where they used separate Ti and Ag targets, and they obtained a structure consisting mainly of the TiN and TiON phase and with a small share of TO2. Ag nanoparticles with a size of 2 nm in the ceramic matrix were obtained by Fischer D., Influence of substrate temperature and silverdoping on the structural and optical properties of TO2 films (Thin Solid Films, 2016, 598, 204-213) but in the coating produced in the vapor deposition process. Another publication: Zhiming Zhao et al., Enhanced raman scattering and photocatalytic activity of TO2 films, with embedded Ag nanoparticles deposited by magnetron sputtering (Journal of Alloys and Compounds, 2016, 679, 8893) reveals the possibility of obtaining a coating in the process of magnetron sputtering with Ag nanoparticles with a size of approx. 16 nm, and the publication by Adochite R.C. et al., The influence of annealing treatments on the properties of Ag: TiO2, nanocomposite films prepared by magnetron sputtering (Applied Surface Science, 2012, 258, 4028-4034) shows that, immediately after deposition, Ag particles with a size of approx. 5 nm.

Hyett G. et al., In The use of combinatorial chemical vapor deposition in the synthesis of Ti (3-delta) O4N with 0.06 <delta <0.25: a titanium oxynitride phase isostructural to anosovite (Journal

PL 240 989 B1

American Chemical Society, 2007, 129 (50), 15541-8), presented the possibility of obtaining a phase

Ti2.8O4N produced in the process of chemical vapor deposition, while the Ti2.8O4N phase in silver and nitrogen modified titanium dioxide coatings in the reactive magnetron sputtering and annealing process has not been identified so far. There is also known from the patent specification PL 210206 B1 a solution comprising a method for producing a thin layer of Eu-doped TiO2 and a thin layer of Eu-doped TiO2 for use in microelectronics and materials engineering as a thin nanocrystalline layer with high luminescent capacity. Another patent specification PL 200159 B1 discloses a method of depositing a photocatalytic coating by sputtering, containing TiO2 partially crystallized in the form of anatase on a transparent or translucent carrier substrate, such as glass, ceramic or plastic. The spraying shall be made on the substrate at a pressure of at least 2 Pascals. The invention also includes a substrate so coated, in which the above-mentioned coating is the last layer of a layer system of thin anti-reflective layers. Another patent specification PL 216050 B1 discloses a method for producing a thin film, which consists in the working surface of the target with the admixtures of vanadium, niobium and tantalum, which is the cathode, treatment, and then in the magnetron sputtering of the titanium target doped in a low-pressure oxygen plasma a thin layer of titanium dioxide doped with vanadium, niobium and tantalum is applied to the substrates, the total amount of impurities in the target being from 7 to 30 at%. The invention also relates to a thin film which is characterized by a high step capacity and a reversible change in resistance at a certain temperature.

The aim of the invention is to develop a method of carrying out the magnetron sputtering and annealing process, which provides the possibility of obtaining a coating of titanium dioxide modified with silver and nitrogen with an original structure, which, when applied to a ceramic substrate, would exhibit very good antibacterial properties, better than the coatings of titanium dioxide (TiO2) and titanium dioxide with addition of silver (TiO2: Ag).

A method of producing a transparent coating of titanium dioxide modified with silver and nitrogen in the process of reactive magnetron sputtering and annealing, characterized by the fact that a target cathode made of titanium with a purity of 99.7 - 99.995%, in the shape of a disc with a diameter of 25 mm with Ag rods with a purity of 99, 9%, with a diameter of 2 mm in the amount of 3 - 4 bars located in holes drilled perpendicular to the surface of the target, symmetrically spaced every 120 ° for 3 bars or every 90 ° for 4 bars at a distance of 8.45 mm from the center of the target are magnetronized in time 30 - 40 min, near the borosilicate glass substrate, which is placed parallel to the cathode, in the presence of a gas mixture of Ar: 75% ± 2%, O2: 23% ± 2% and N2: 2% ± 1% and at a pressure of 0.4 - 0.6 Pa, and then the coating is annealed at the temperature of 450 - 500 ° C for 1 - 1.5 h in nitrogen atmosphere with a purity of 99.999%.

Preferably, silver rods are placed in drilled holes in the target next to the zone of greatest erosion so that the Ag content is 0.6 ± 0.1% of the target area. Also preferably, at the beginning and after the coating deposition process, the oxide layer was removed from the surface of the titanium target with Ag rods by magnetron sputtering in argon plasma at a magnetron power density of 14 W / cm ² for 20 - 30 min at a pressure in a vacuum chamber of 0.4 - 0.6 Pa. Additionally and preferably, the glass substrate is placed 45-60mm from the target. Furthermore, it is preferred that reactive magnetron sputtering is carried out with a DC supply at a magnetron power density of 18 ± 2 W / cm ² .

The layer of titanium dioxide modified with silver and nitrogen, in which the titanium dioxide is present in the rityl and anatase phase, according to the essence of the invention, consists of the phases: anatase, Ti2.8O4N, rutile and Ag nanoparticles with crystallite size up to several nm and a small relative volume of amorphous structure with the Ag concentration in the coating being 3.3 ± 3.8 at.%. The phase structure was determined as a result of XRD studies, SAED electron diffraction and HRTEM images.

The transparent coating obtained by the method according to the invention, with transmittance in the range of 50-80% in the visible range, due to the original phase composition, shows a significant increase in the absorbance of visible radiation and higher bactericidal properties than titanium dioxide coatings with the addition of silver or nitrogen-doped titanium dioxide. The produced coating of titanium dioxide modified with silver and nitrogen, activated with UV radiation for an hour before the experiment, after the introduction of bacteria to the surface and exposure to visible light, shows a reduction of Staphyloccocus aureus bacteria by 33.7 and 45% in compared to the coating of titanium dioxide (TO2) and by 12.4 and 8.2% compared to the coating of titanium dioxide with the addition of Ag (TiO2: Ag). In addition, it has an antibacterial effect after 24 hours.

Claims (6)

In the vacuum working chamber of the magnetron, a cathode target made of titanium with a purity of 99.995%, a diameter of 25.4 mm and a thickness of 3 mm, with 3 silver bars symmetrically spaced at 120 ° 99.9%) with a diameter of 2 mm. Due to the difference in silver and titanium sputtering speed (5.7x), the Ag rods are placed symmetrically next to the zone of greatest erosion of the target at a distance of 8.45 mm from the center of the target. The borosilicate glass substrate - showing thermal resistance at a temperature of 500 ° C, is placed at a distance of 45 mm from the target, parallel to it. Then, a vacuum of 5-10-6 Pa is obtained in the vacuum chamber, and then the oxide layer is removed from the target by magnetron sputtering in argon plasma at the magnetron power density of 14 W / cm2 for approx. 20 min. Then it is expected to create a vacuum of 5-10-6 Pa and the gases Ar O2 and N2 are introduced with the proportion of Ar: 75%, O2: 23% and N2: 2% (by volume for normal conditions: p = 1 atm, T = 25 ° C). The pressure in the chamber during the process is set at about 0.55 Pa. The growth rate of the 18 ± 2 W / cm2 magnetron power density coating is approx. 50 nm / min, hence the coating with a thickness of approx. 200 nm is applied for approx. 4 min. After deposition, the coated carrier is subjected to an annealing process in a heating furnace at 500 ° C for 1 hour under nitrogen atmosphere (99.999% purity). The heating speed is approx. 100 ° C / min. Cooling takes place outside the heating furnace in a protective atmosphere. In this way, a transparent layer of titanium dioxide modified with silver and nitrogen is obtained, consisting of the phases: anatase, Ti2.8O4N, rutile and Ag nanoparticles with a crystallite size of up to several nm and a small relative volume of the amorphous phase, while the Ag concentration in the coating is 3.5 ± 10.2% at. The coating has antibacterial properties after the incubation time of the bacteria on the coating for 3 and 5 hours, the reduction of Staphyloccocus aureus bacteria was achieved by 33 and 45%, respectively, compared to the coating of titanium dioxide (TO2) and by 12 and 8% compared to the coating of titanium dioxide with the addition of Ag ( TiO2: Ag). The coating shows an antibacterial effect after 24 hours. P r x l a d 2. In the vacuum working chamber of the magnetron, a 99.7% pure cathode target, 25.4 mm in diameter and 3 mm thick, with 4 silver bars symmetrically spaced every 90 ° (99.9% purity) is placed. %) with a diameter of 2 mm. Due to the difference in the speed of silver and titanium sputtering (5.7x), the Ag rods are placed symmetrically next to the zone of greatest erosion of the target at a distance of 8.45 mm from the center of the target. The borosilicate glass substrate - showing thermal resistance at a temperature of 500 ° C, is placed at a distance of 55 mm from the target parallel to it. Then a vacuum of 5-106 Pa is obtained in the vacuum chamber, and then the target oxide layer is removed by magnetron sputtering in argon plasma with a magnetron power of 14W / cm? for approx. 2 Avoid. Then it is expected to create a vacuum of 5-10-6 Pa and the gases Ar, O2 and N2 are introduced with the proportion of Ar: 75%, O2: 22% and N3: 3% (by volume for normal conditions: p = 1 atm, T = 25 ° C). The pressure in the chamber during the process is obtained at the level of about 0.5 Pa. The coating growth rate for the magnetron power density 18 ± 2 W / cm2 is approx. 50 nm / min, hence the coating with a thickness of approx. 200 nm is applied for approx. 4 min. After deposition, the coatings are subjected to an annealing process at the temperature of 480 ° C for 1.5 hours under nitrogen atmosphere (99.999% purity). The heating speed is approx. 100 ° C / min. Cooling takes place outside the heating furnace in a protective atmosphere. In this way, a transparent coating of silver and nitrogen modified titanium dioxide is obtained, consisting of 2 phases: anatase, Ti2.8O4N, rutile and Ag nanoparticles with crystallite size up to several nm and a small relative volume of the amorphous phase, while the Ag concentration in the coating is 3.7 ± 0.2% at. The coating has antibacterial properties after the incubation time of bacteria on the coating for 3 and 5 hours, reduction of Staphyloccocus aureus bacteria by 33 and 45% respectively compared to the coating of titanium dioxide (TiO2) and by 12 and 8% compared to the coating of titanium dioxide with the addition of Ag (TiO2) : Ag). In addition, it has an antibacterial effect after 24 hours. Patent claims 1. The method of producing a transparent coating of titanium dioxide modified with silver and nitrogen in the process of reactive magnetron sputtering and annealing, characterized by the fact that the target cathode is made of titanium with a purity of 99.7 - 99.995%, in the shape of a disc with a diameter of 25 mm with Ag rods of purity 99.9%, with a diameter of 2 mm in the amount of 3 - 4 bars located in holes drilled perpendicular to the surface of the target, arranged symmetrically every 120 ° for 3 bars or every 90 ° for 4 bars, at a distance of 8.45 mm from the center of the target sprays PL 240 989 B1 is magnetronized for 30-40 min, near the borosilicate glass substrate, which is placed parallel to the cathode, in the presence of a gas mixture of Ar: 75% ± 2%, O2: 23% ± 2% and N2: 2% ± 1% and at a pressure of 0.4-0.6 Pa, and then the coating is annealed at the temperature of 450 - 500 ° C for 1 - 1.5 hours in a nitrogen atmosphere with a purity of 99.999%. 2. The method according to p. The method of claim 1, wherein the silver rods are placed symmetrically in drilled holes in the titanium target such that the Ag content is 0.6 ± 0.1% of the target area. 3. The method according to p. The method of claim 1, characterized in that at the beginning and after the coating deposition process, the oxide layer is removed from the surface of the titanium target with Ag rods by magnetron sputtering in argon plasma at a magnetron power density of 14 ± 2 W / cm ² and a vacuum chamber pressure of 0.4 - 0.6 Pa for 20 - 30 min. 4. The method according to p. The method of claim 1, wherein the glass substrate is positioned at a distance of 45-60 mm from the target. 5. The method according to p. The method of claim 1, wherein the reactive magnetron sputtering is carried out with a DC power supply at a power of 18 ± 2 W / cm ² . 6. The coating of titanium dioxide modified with silver and nitrogen, in which the titanium dioxide occurs in two polymorphs, i.e. rutile and anatase, characterized in that it consists of a rutile phase in the amount of 38 - 39 vol.%, Anatase phase in the amount of 19 - 22 % vol., Ti2.8O4N phase in the amount of 32 - 35 vol.%, amorphous structure in the amount of 7 - 8 vol.%. and Ag nanoparticles, the Ag concentration in the coating being 3.5-3.8 at.%, and the crystallite size of the individual phases is not more than 20 nm.