Optical properties of SrxBa1−xNb2O6 nanoscale films (x = 0.5 and 0.61) grown by RF-cathode sputtering in an oxygen atmosphere

The research findings of the phase composition, nanostructure and optical properties of strontium–barium niobate thin films are discussed. Sr[Formula: see text]Ba[Formula: see text]Nb2O6 nanosized films ([Formula: see text] = 0.5 and 0.61) were characterized by XRD, SEM and AFM studies. Reflective multi-angle ellipsometry and spectrophotometry were used to determine the optical parameters (refractive index, its dispersion, and thickness of the damaged surface layer) of thin films. It was shown that SBN-50 and SBN-61 thin films were grown [Formula: see text]-oriented on Al2O3 (0001) and heteroepitaxial on MgO (001) substrates. The increase of refractive index, approaching its maximum value in the bulk material for a given composition as the film thickness increases, is observed.

Biopolymer Composites with Ti/Au Nanostructures and Their Antibacterial Properties

In this study, we have aimed at the preparation and characterization of poly-l-lactic acid (PLLA) composites with antibacterial properties. Thin bilayers of titanium and gold of various thickness ratios were deposited on PLLA by a cathode sputtering method; selected samples were subsequently thermally treated. The surface morphology of the prepared composites was studied by atomic force, scanning electron, and laser confocal microscopy. The chemical properties of the composites were determined by X-ray photoelectron and energy-dispersive X-ray spectroscopy in combination with contact angle and zeta potential analyses. The antibacterial properties of selected samples were examined against a Gram-negative bacterial strain of E. coli. We have found that a certain combination of Au and Ti nanolayers in combination with heat treatment leads to the formation of a unique wrinkled pattern. Moreover, we have developed a simple technique by which a large-scale sample modification can be easily produced. The dimensions of wrinkles can be tailored by the sequence and thickness of the deposited metals. A selected combination of gold, titanium, and heat treatment led to the formation of a nanowrinkled pattern with excellent antibacterial properties.

PEGylated Gold Nanoparticles Grafted with N-Acetyl-L-Cysteine for Polymer Modification

The subjects of this work were the enhancement and determination of the stability and other properties of gold nanoparticles (AuNPs) in an aqueous solution, gold nanoparticle immobilization, and further surface grafting on polyethylene naphthalate (PEN). Gold nanoparticles in PEG with a subsequent water solution addition were prepared using cathode sputtering; for the subsequent surface activation, two different solutions were used: (i) sodium citrate dihydrate (TCD) and (ii) N-acetyl-L-cysteine (NALC). The aim of this work was to study the effect of the concentration of these solutions on AuNPs stability, and further, the effect of the concentration of gold nanoparticles and their morphology, and to describe the aging process of solutions, namely, the optical properties of samples over 28 days. Stabilized AuNPs were prepared in an N-acetyl-L-cysteine (NALC) system and subsequently immobilized with NALC. The surface chemistry modification of AuNPs was confirmed using HRTEM/EDS. Gold nanoparticles were successfully immobilized with NALC. Grafting of the modified PEN from a solution of colloidal gold stabilized in the PEG–H2O–NALC system led to the polymer surface functionalization.

Formation of Nitrogen Doped Titanium Dioxide Surface Layer on NiTi Shape Memory Alloy

NiTi shape memory alloys are increasingly being used as bone and cardiac implants. The oxide layer of nanometric thickness spontaneously formed on their surface does not sufficiently protect from nickel transition into surrounding tissues, and its presence, even in a small amount, can be harmful to the human organism. In order to limit this disadvantageous phenomenon, there are several surface engineering techniques used, including oxidation methods. Due to the usually complex shapes of implants, one of the most prospective methods is low-temperature plasma oxidation. This article presents the role of cathode sputtering in the formation of a titanium dioxide surface layer, specifically rutile. The surface of the NiTi shape memory alloy was modified using low-temperature glow discharge plasma oxidation processes, which were carried out in two variants: oxidation using an argon + oxygen (80% vol.) reactive atmosphere and the less chemically active argon + air (80% vol.), but with a preliminary cathode sputtering process in the Ar + N2 (1:1) plasma. This paper presents the structure (STEM), chemical composition (EDS, SIMS), surface topography (optical profilometer, Atomic Force Microscopy—AFM) and antibacterial properties of nanocrystalline TiO2 diffusive surface layers. It is shown that prior cathodic sputtering in argon-nitrogen plasma almost doubled the thickness of the produced nitrogen-doped titanium dioxide layers despite using air instead of oxygen. The (TiOxNy)2 diffusive surface layer showed a high level of resistance to E. coli colonization in comparison with NiTi, which indicates the possibility of using this surface layer in the modification of NiTi implants’ properties.

CONTROL OF IONIZATION PROCESSES IN MAGNETRON SPUTTERING SYSTEM BY CHANGING MAGNETIC FIELD CONFIGURATION

This work is devoted to measuring the function of the distribution of charged particles of gas-discharge plasma in a magnetron sputtering system under conditions of non-potential "earth". Measurements are carried out with the help of a three-electrode probe, which is installed in the cathode sputtering zone, with unsafe electrodes and housing. The selection of the analyzed particles was carried out through a screen located under floating potential. Effect of additional magnetic insulation anode of MSS МАG-5 on ion and electron distribution functions was investigated.

Структурные характеристики выращенных методом RF-катодного напыления тонких пленок Sr-=SUB=-0.61-=/SUB=-Ba-=SUB=-0.39-=/SUB=-Nb-=SUB=-2-=/SUB=-O-=SUB=-6-=/SUB=-/ MgO(001)

Thin films of the congruent composition of the barium-strontium niobates solid solutions Sr0.61Ba0.39Nb2O6 (SBN: 61) with thicknesses from 30 to 630 nm on a MgO (001) substrate were fabricated by RF-cathode sputtering in an oxygen atmosphere. By X-ray diffraction it was found that the films are epitaxial and there are no impurities in them. In the films, there is practically no unit cell deformation in the interface plane and tensile strain is present in the normal to the surface direction, which increases with decreasing film thickness. Dielectric measurements indicate high tunability in the films.

Диэлектрические и сегнетоэлектрические свойства тонких гетероэпитаксиальных пленок SBN-50

The phase transformations and ferroelectric characteristics of thin heteroepitaxial barium-strontium niobate SBN-50 films grown by RF cathode sputtering in an oxygen atmosphere were studied using dielectric spectroscopy and scanning probe microscopy (in the modes of force microscopy of the piezoresponse and Kelvin modes). It is shown that the films are characterized by a low surface roughness, an average size of ferroelectric domains of ~ 100 nm, and spontaneous polarization directed from the substrate to the film surface. Differences in the magnitude of the surface potential signal and its relaxation for the regions polarized at +10 V and –10 V were established. The nature of the change in the dielectric parameters in the temperature range T = 275–500 K indicates that the material belongs to ferroelectric relaxors. The reasons for the established regularities are discussed.

Structural behavior of RF magnetron sputtered cuprous oxide (Cu2O) films

In this paper a Cu2O thin films, were deposited using RF sputtering technique. Sputtering process can be defined as ejection atoms of material surface due to positive ions bombardment of (mostly) inert gas, sometimes called cathode sputtering. Then the thin films were characterized by XRD. The results obtained showed that, the thin films had a polycrystalline structure with cubic lattice unit cell. strongest peak was seen at 61.3967 degree, and FWHM was at 0.215 degree, while lattice constant was 4.26 Aº. The average grain size was 44.87 nm. While AFM analysis showed that the increasing of four samples temperature (523, 573, 623 and 673) Kelvin, led to increase of roughness average from (3.39 to 9.2) nm, and ten points height from (13.7 to 36.3). On the other hand granularity cumulation distribution charts showed that the average diameter was varied from (43.31 to 51.28) nm with grain numbers ( 739, to 414) respectively