Algirdas Selskis

Center for Physical Sciences and Technology | CPST · Characterization of Materials Structure

Currently, there is a growing interest in the use of natural materials in various fields of science, technology and environmental protection due to their availability, low-cost, non-toxicity and biodegradability. Chitosan, natural clay of local origin, montmorillonite, zeolite, cross-linking agents (epichlorohydrin, sodium tripolyphosphate, glutara...

Generation of hybrid gold-silver nanoparticles from different metal ratios by thermal heating thin metal films on a glass surface with a nanosecond pulsed laser is presented. The optical properties of obtained nanoparticles are dependent on localized surface plasmon resonance (LSPR), which can be tuned in the range of 400–530 nm by varying the rati...

Magneto-plasmonic nanoparticles were fabricated using a 1064 nm picosecond-pulsed laser for ablation of Fe/Au and Fe/Au/Fe composite thin films in acetone. Nanoparticles were characterized by electron microscopy, ultraviolet-visible (UV-VIS) absorption, and Raman spectroscopy. Hybrid nanoparticles were arranged on an aluminum substrate by a magneti...

Unique electronic properties of graphene offer highly interesting ways to manipulate the functional properties of surfaces and develop novel structures which are sensitive to physical and chemical interactions. Nano-crystalline graphene is frequently preferable to crystalline monolayer in detecting devices. In this work, nano-crystalline graphene l...

Beaming and coherent thermal emission of the hybrid surface plasmon phonon polaritons (SPPhPs) was numerically and experimentally investigated employing the n-GaN surface relief gratings (SRGs) shaped in a linear and radial geometry. The polariton propagation losses were minimized numerically with the help of a rigorous coupled wave analysis model,...

Porous 3D Cu layers with the following average parameters: thickness ~35 µm, pore density ~4.0 × 106 cm−2, and pore sizes ~25 µm were electrodeposited from an acidic sulphate electrolyte, and the suitability of different electrochemically active surface area determination methods for characterising these electrodes was assessed. Structural characte...

Electrochemical deposition of silicon at room temperature is problematic due to the intrinsically low conductivity of the deposits. This study reports the photoelectrochemical (PEC) deposition of silicon (Si) and silicon–carbon (Si–C) layers from an ionic liquid at 40 °C using silicon tetrachloride (SiCl4) as a silicon precursor. Amorphous layers a...

A laser-induced graphene (LIG) modified with chitosan (Chit) and conducting polymer polyfolate (PFA) was used as a base to develop a flat and flexible pH sensor. LIGs were formed using two different irradiation wavelengths of 355 nm and 532 nm. Depending on the wavelengths, the obtained electrodes were named LIG355 and LIG532. Microscopic imaging r...

Electrochemical deposition of silicon at room temperature is problematic due to intrinsically low conductivity of the deposits. This study reports the photoelectrochemical (PEC) deposition of silicon (Si) and silicon–carbon (Si–C) layers from an ionic liquid at temperature 40 oC using silicon tetrachloride (SiCl4) as a silicon precursor. Amorphous...

A series of highly flexible and environmentally friendly composites based on polydimethylsiloxane (PDMS) filled with 200 nm size ferroelectric BaTiO3 (BTO) particles at different concentrations (from 7 to 23 vol %) have been fabricated by a simple dispersion method. The dielectric, piezoelectric, and ultrasonic properties have been studied. The fer...

We propose a simple, fast, and low-cost method for producing Au-coated black Si-based SERS-active substrates with a proven enhancement factor of 10^6. Room temperature reactive ion etching of silicon wafer followed by nanometer-thin gold sputtering allows the formation of a highly developed lace-type Si surface covered with homogeneously distribute...

Bulk polylactic acid (PLA)/multiwall carbon nanotube (MWCNT) composites were prepared and investigated in wide frequency ranges (20 Hz–1 MHz and 24–40 GHz). It was determined that the percolation threshold in bulk PLA/MWCNT composites is close to 0.2 vol.% MWCNT. However, the best microwave dielectric properties and absorption were observed in comp...

Complex gold nanostructures fabricated on the surface of metal have a high potential for being used as plasmonic nanostructures. The precise shape and dimensions management of the structures enables accurate control of plasmonic properties. In this work, the formation of gold nanobumps, nanocones, and nanojets by laser direct writing technique was...

Multilayered phosphate bonded CoFe2O4–BaTiO3–CoFe2O4 (CBC) and BaTiO3–CoFe2O4 – BaTiO3 (BCB) multiferroic structures were formed by means of uniaxial pressing. The dielectric properties were studied in 20 Hz – 1 GHz frequency and 120–500 K temperature ranges. The complex dielectric permittivity is 15–0.17i for CBC and 22–0.04i for BCB, it is temper...

To fabricate graphene-based high-frequency electronic and optoelectronic devices, there is a high demand for scalable low-contaminated graphene with high mobility. Graphene synthesized via chemical vapor deposition (CVD) on copper foil appears promising for this purpose, but residues from the polymethyl methacrylate (PMMA) layer, used for the wet t...

Ceramic composites with nanoparticles are intensively investigated due to their unique thermal, mechanic and electromagnetic properties. In this work, dielectric properties of phosphate ceramics with round silver nanoparticles of various sizes were studied in the wide frequency range of 20 Hz–40 GHz for microwave shielding applications. The percola...

Improving the performance of kesterite solar cells requires high-quality, defect-free CZTS(Se) films with a reduced number of secondary phases and impurities. Post-annealing of the CZTS films at high temperatures in a sulfur or selenium atmosphere is commonly used to improve the quality of the absorbing material. However, annealing at high-temperat...

Biocompatible single‐crystal diamond needles enriched with nitrogen and silicon vacancy (NV and SiV) color centers in a controllable manner via modified chemical vapor deposition synthesis are employed by Lena Golubewa, Polina Kuzhir and co‐workers (article number 2200631) for improved all‐optical thermometry based on the temperature dependence of...

The high efficiency of perovskite solar cells strongly depends on the quality of perovskite films and carrier extraction layers. Here, we present the results of an investigation of the photoelectric properties of solar cells based on perovskite films grown on compact and mesoporous titanium dioxide layers. Kinetics of charge carrier transport and t...

Here we report the optimization of the fabrication conditions for AuNi bimetallic catalysts supported on self-ordered titania nanotube arrays (AuNi-TiO2ntb). A series of efficient AuNi-TiO2ntb catalysts with small amounts of Au in the range of 1.74 to 15.7 μgAu·cm−2 have been fabricated by anodization, electroless Ni plating, and galvanic displacem...

Monitoring of tiny intracell temperature variations is of high importance to understand the mechanisms of exothermic/endothermic processes inside the living cells. Small shifts in thermal balance may drastically influence cell functioning and induce pathological conditions. By using biocompatible diamond single‐crystal microneedles enriched with ni...

Hafnium oxide (HfO 2 ) films on silicon have the potential for application in photovoltaic devices. However, very little is known about the photoelectrochemical and protective properties of HfO 2 films on Si. In this study, ultrathin films of HfO 2 in the range of 15–70 nm were deposited on p-Si and Au substrates by atomic layer deposition (ALD). G...

While silica is chemically stable in most acid electrolytes, its properties could significantly change due to electrolyte absorption. We demonstrate the photoelectrochemical and nanogravimetric features that allow identification of electrolytic transformation of Si-SiO 2 interface. To that end, photoresponsivity of p-type silicon with ultrathin the...

Performance of a perovskite solar cell is largely influenced by the optoelectronic properties of metal halide perovskite films. Here we study the influence of cesium concentration on morphology, crystal structure, photoluminescence and optical properties of the triple cation perovskite film. Incorporation of small amount (x = 0.1) of cesium cations...

In the present work, three different techniques were used to obtain a 3D view of the SEM images of adipose tissue samples taken from volunteer obese patients by only freely available software. The extrapolation of spatial data demonstrates the most promising results compared to the results of a stereoscopic view or interactive surface plots. The 3D...

Triple-cation perovskite/silicon tandem solar cell Ašmontas S., Gradauskas J., Grigucevičienė A., Leinartas K., Lučun A., Mujahid M., Petrauskas K., Selskis A., Sužiedėlis A., Šilėnas A. and Širmulis E. Center for Physical Sciences and Technology, Saulėtekio Avenue 3, 10257 Vilnius, Lithuania office@ftmc.lt Received: 06.07.2022 Abstract. A tandem s...

In this study, sodium borohydride oxidation has been investigated on the platinum nanoparticles modified copper/titanium catalysts (PtNPsCu/Ti), which were fabricated by employing the electroless copper plating and galvanic displacement technique. ICP-OES, XRD, FESEM, and EDX have been used to characterize PtNPsCu/Ti catalysts’ composition, structu...

The formation of kesterite (Cu2ZnSnS4) in a quartz tube furnace attached to a special separate chamber for evaporation of sulphur has been studied. Ar gas was used to transport the sulphur vapour to the reaction zone at the centre of tube furnace. A Cu-Zn-Sn (CZT) precursor on the Mo/glass substrate was formed by the electrochemical deposition of a...

Light emitting diode structures of quaternary GaInAsBi bismide quantum wells with AlInAs barriers were grown on InP substrates by molecular-beam epitaxy. Intermediate additional layers of GaInAs were inserted between the bismide quantum wells and AlInAs barriers to reduce the electron size-quantization energy and, therefore, the energy of optical t...

Surface-enhanced Raman spectroscopy (SERS) substrates fabricated using a repeated laser treatment of thin gold films are demonstrated. The presented SERS substrates consist of the gold nanoparticles, whose density and size depend on the used film thickness and number of treated films. The larger number of the treated gold film layers increases the...

Composite materials with 83 wt.% of the 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 distributed in phosphate-bonded ceramics were prepared at three different pressures. A phosphate matrix comprises a mixture of an aluminum phosphate binder and melted periclase, MgO. All samples demonstrate a homogeneous distribution of the ferroelectric perovskite phase and are...

The goal of this study is development of ultra-sensitive and reproducible SERS platform based on novel magnetoplasmonic nanoparticles produced by laser ablation. The magnetic part of hybrid nanoparticles ensures manipulation of the nanoparticles by magnetic field by arranging them at biological surfaces in a special geometry resulting in high and r...

Aqueous Na-ion based batteries are considered promising candidates for replacing Li-ion technologies, especially in the area of stationary energy storage. Research and development of novel electrode materials remain a central research effort in this field. NASICON-structured NaTi2(PO4)3 phosphate framework has attracted a great deal of attention an...

Electron dynamics in the polycrystalline bismuth films were investigated by measuring emitted terahertz (THz) radiation pulses after their photoexcitation by tunable wavelength femtosecond duration optical pulses. Bi films were grown on metallic Au, Pt, and Ag substrates by the electrodeposition method with the Triton X-100 electrolyte additive, wh...

This article deals with the dielectric properties of polydimethylsiloxane (PDMS) nanocomposites filled with SrTiO 3 nanoparticles. The investigations were performed over a very broad range of frequencies (20 Hz to 3 THz). Almost no dielectric dispersion was observed in all the composites at room temperature over the entire range of measurement freq...

Evaldas Stankevicius and co‐workers (article number 2100027) demonstrate the formation of large‐scale gold microbump arrays generating hybrid lattice plasmon polaritons in the visible to near‐infrared range using direct laser writing technique. The demonstrated method shows relevant technological progress in the formation of large‐scale metallic gr...

Recent developments of nanostructured coatings have reached a point where extensive investigations within multi-layer systems are necessary for further implementation in novel photonic systems. Although sculptured thin films are explored for decades, no optical and structural measurements have been performed for anisotropic nanostructured multi-lay...

Surface plasmon polaritons (SPPs) based light–matter interactions play a major role in photonic sensor applications. In order to implement such sensors in microchip devices or reduce the fabrication costs, a method with high flexibility and large‐scale capabilities must be developed. Here, the formation of large‐scale gold microbumps arrays by usin...

Cesium-containing triple cation perovskites are attracting significant attention as suitable tandem partners for silicon solar cells. The perovskite layer of a solar cell must strongly absorb the visible light and be transparent to the infrared light. Optical transmittance measurements of perovskite layers containing different cesium concentrations...

The dielectric/electric properties of the Ni@C (carbon-coated Ni)/epoxy composites and Ni@C/MWCNTs (multi-walled carbon nanotubes)/epoxy composites loaded with fixed MWCNTs amount just below the percolation threshold (0.09 vol.%) and Ni@C at different concentrations up to 1 vol.% were investigated in broad frequency (20 Hz–40 GHz) and temperature (...

Environmentally friendly alternatives to chromium—phosphate/molybdate and cerium-modified phosphate/molybdate conversion coatings—were deposited on a carbon steel surface. Different surface analytic techniques were applied to obtain complementary information on the composition, element distribution morphology and inner structure of the coatings in...

The 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 ceramic films were prepared using the water-based tape casting method. Two main components of the slurry are water and solids. The concentrations of other chemicals, the surfactant and binder, are at the level of 1 wt.%. Both binder and surfactant are eco-friendly polymers. Additional chemicals are not required. Th...

A phosphate/molybdate and cerium-modified phosphate/molybdate conversion coatings were deposited on a carbon steel surface and their protective and self-healing abilities were evaluated. Surface morphology and inner structure of the coatings were examined using FE-SEM-FIB and TEM techniques, chemical composition and element distribution depth profi...

The composite material filled with nano-sized BaTiO3 and Fe3O4 was designed and studied. The aluminium phosphate ceramics was used as a matrix. The XRD analysis demonstrates only the crystalline structure of the fillers used. The thermogravimetric analysis proves the thermal stability of the composites up to 950 K. The Maxwell–Wagner relaxation was...

This paper deals with the electrical properties of polydimethylsiloxane nanocomposites filled with Ag nanoparticles (AgNPs) of different sizes. The measurements were carried out over a very broad range of frequencies (20 Hz‐40 GHz), and the results showed that the percolation threshold in the composites is close to 20 vol% and that it is almost ind...

Black silicon (bSi) refers to an etched silicon surface comprising arrays of microcones that effectively suppress reflection from UV to near-infrared (NIR) while simultaneously enhancing the scattering and absorption of light. This makes bSi covered with a nm-thin layer of plasmonic metal, i.e., gold, an attractive substrate material for sensing of...

In this study, the carbon powder supported gold nanoparticles composites (AuNPs/C) were prepared via the chemical reduction method by employing sodium citrate or a complex mixture of glucose and ascorbic acid as reducing agents in the presence of small amounts of different halide ions (Cl–, Br–, I–). The electrocatalytic activity of the synthesized...

The electrochemical stability and durability of ZnCo alloy thin layers deposited on the titanium surface (denoted as ZnCo/Ti) and those modified by small amounts of Au nanoparticles (denoted as AuZnCo/Ti) prepared via the electrochemical metal deposition technique and a simple galvanic displacement have been investigated in alkaline sodium borohydr...

Integration of living cells with nonbiological surfaces (substrates) of sensors, scaffolds, and implants implies severe restrictions on the interface quality and properties, which broadly cover all elements of the interaction between the living and artificial systems (materials, surface modifications, drug-eluting coatings, etc.). Substrate materia...

In this article, we present a systematic investigation of the influence of CdS layer thickness on the structural and compositional properties of CZTSSe films and photovoltaic performance of superstrate solar cell devices. The selenization of the CZTS films results in Cd diffusion into the absorbing layer. This leads to a significant change in the l...

Thin Mg–Nb alloy films having a thickness below 1 µm were deposited by magnetron sputtering on glass substrates with Nb concentrations of 4, 26 and 32 at.%. Distribution of the elements within the deposits was identified by a scanning transmission electron microscope (STEM) equipped with a high angle annular dark field (HAADF) detector, which showe...

Niobium-doped titanium dioxide (Ti1−xNbxO2) films were grown on p-type Si substrates at low temperature (170 °C) using an atomic layer deposition technique. The as-deposited films were amorphous and showed low electrical conductivity. The films became electrically well-conducting and crystallized into the an anatase structure upon reductive post-de...

Amorphous hafnium oxide films from 15 to 60 nm in thickness were deposited by atomic layer deposition (ALD) on AZ31 magnesium alloy. The films exhibited high anticorrosion performance in the Hank's balanced salt solution, whose pH and ion concentrations were close to those of the human blood plasma. Voltammetry identified reduction of the corrosion...

The electrical properties of epoxy/MWCNT (multi-walled carbon nanotubes)/MnFe2O4 hybrid composites loaded with MWCNTs (below, 0.09 vol.%, and above, 0.58 vol.%, percolation threshold) and varying concentrations of MnFe2O4 up to 10 vol.% were studied in a wide frequency range (20 Hz–40 GHz) at different temperatures (20 K–500 K). At low frequencies,...

MnO2/C nanocomposites have been prepared using a simple onestep microwave heating method by applying different concentrations of cationic surfactant – cetyl trimethylammonium bromide (CTAB). The morphology and composition of the prepared MnO2/C nanocomposites have been investigated using X-ray photoelectron spectroscopy (XPS), field-emission scanni...

In this study, a fiber-shaped Co coating was electroplated on the Cu surface followed by the deposition of Pt crystallites using the galvanic displacement method. The electrochemical behavior of the prepared Cofiber and Pt nanoparticles decorated Cofiber catalysts were evaluated in order to provide insights into the electro-oxidation of N2H4 in an...

The dielectric properties of epoxy/MWCNT (multi-walled carbon nanotubes)/MgO hybrid composites with a fixed MWCNT amount of 0.12 vol.% (0.2 wt.%) and varying MgO concentrations up to 3 vol.% were investigated in broad frequency (20–40 GHz) and temperature (20–500 K) ranges. The composites with up to 2 vol.% MgO nanoparticles concentration showed a...

Broadband dielectric properties of epoxy composites containing the different additions of manganese ferrite (MnFe2O4) with two spherical particle size (28 and 60 nm) have been studied in the wide temperature range from 150 K to 500 K. The percolation thresholds in such systems are 30 and 29.3 vol.% for small and large MnFe2O4 particles, respectivel...

Hybrid composite materials based on an aluminium phosphate matrix with silicon carbide whiskers and multi-walled carbon nanotubes were studied in a wide frequency range (20 Hz to 36 GHz). It was demonstrated, that the addition of the silicon carbide whiskers enhances the dielectric permittivity and conductivity. This was explained by the difference...

This work presents the investigation of the electrochemical oxidation of hydrazine and sodium borohydride ions in alkaline solutions on the Au nanoparticles modified ZnCo coating surface, which was deposited on the titanium substrate (termed as AuZnCo/Ti). The AuZnCo/Ti catalysts were prepared via a facile electrochemical deposition technique follo...