Georgiana Bulai

Universitatea Alexandru Ioan Cuza | UAIC · CERNESIM

The ellipsometric analyses reported in this paper present a novelty by bringing an in-depth optical investigation of some ternary organic blends. This study focuses on the tunability and control of the relative permittivity of active layers by varying the weight ratio of blended materials spin-coated as thin films. To investigate this, an extensive...

In this paper, we investigate the decomposition of a toxic organic compound, Rhodamine B, by the photocatalytic activities of undoped and nitrogen-doped ZrO2 thin films, deposited using the HiPIMS technique. The investigation was performed in the presence and in the absence of H2O2, for two types of experimental arrangements: the irradiation of the...

This work addresses the global sustainable development concerns by investigating the enhancement of piezo-photocatalytic efficiency in bismuth ferrite-based thin films synthesized using reactive high-power impulse magnetron sputtering. The influence of substrate type and Cr addition on structural, optical and ferroelectric properties of bismuth fer...

In the global context of climate change and carbon neutrality, this work proposes a strategy to improve the light absorption of photocatalytic water-splitting materials into the visible spectrum by anion doping. In this framework, reactive high power impulse magnetron sputtering (HiPIMS) of a pure Zr target in Ar/N 2 /O 2 gas mixture was used for t...

TiO2–SiO2 nanocomposite thin films have gained the attention of the scientific community due to their unique physical and chemical properties. In this paper, we report on the fabrication and characterization of a TiO2–SiO2 nanocomposite disk-shaped target. The target was used for the deposition of TiO2–SiO2 nanocomposite thin films on fluorine-dope...

Bismuth ferrite based thin films were grown by RF magnetron sputtering under different experimental conditions. The effects of substrate temperature, Ar:O2 mass flow ratio and gas mixture pressure on the films’ microstructure, phase evolution, optic, ferroelectric and magnetic properties were systematically investigated. The structural analysis res...

Extensive attention and considerable efforts have been made to construct efficient heterogeneous nanoparticulate systems for surface chemical reactions to be active in solar light-driven photodegradation. This work addresses current deficiencies of the nanoparticles-focused systems intended for visible light photodegradation by developing a newly-f...

The addition of rare earth elements the ferrites can lead to significant changes in structural, magnetic and electric properties of bulk materials and also of thin films deposited by pulsed laser deposition. The present study relies on the analysis of the laser induced plasma of three sets of cobalt ferrite targets doped with various concentrations...

Ceramic thin films with variable thicknesses have been used in many applications. In order to protect the petroleum transportation pipes against the harmful H2S action, two ceramic materials as thin layers are proposed. In this article, pulsed laser deposition (PLD) of ceramic layers by in situ time-resolved optical techniques is investigated. Two...

Flower-like ZnO architectures assembled with many nanorods were successfully synthesized through Thermionic Vacuum Arc, operated both in direct current (DC-TVA) and a pulsed mode (PTVA), and coupled with annealing in an oxygen atmosphere. The prepared coatings were analysed by scanning-electron microscopy with energy-dispersive X-ray-spectroscopy (...

Gadolinium (Gd³⁺) substituted zinc manganese ferrite nanoparticles with nominal compositions Zn0.7Mn0.3GdxFe2-xO4 (where x = 0.000; 0.025; 0.050; 0.075; 0.100) were successfully synthetized using co-precipitation method. The synthetized powders were calcined at 500 °C and furthermore pressed into pellets and thermally treated at 650 °C for a second...

High-power laser irradiation interaction with natural polymers in biocomposites and Laser-Induced Chitin Deacetylation (LICD) was studied in this work, in order to produce thin films consisting of chitosan composite. The new method can lead to a cutting-edge technology, as a response to the concern regarding the accumulation of “natural biological...

Due to an attractive combination of chemical and physical properties, silicon carbide (SiC) thin films are excellent candidates for coatings to be used in harsh environment applications or as protective coatings in heat exchanger applications. This work reports the deposition of near-stoichi-ometric and nanocrystalline SiC thin films, at room tempe...

The preparation of antioxidant-coated magnetic nanoparticles (MNPs) has been studied to improve their biocompatibility, i.e. reducing negative side effects. The theoretical study was focused on the interaction of gallic acid (GA) with ionic iron at the surface of nanoparticles that increased reactivity and favors the uniform dispersion in water of...

In this paper, several researches were undertaken related to a violent phenomenon, characterized by a sonic boom, felt on an area of at least 500 km2, shortly followed by the fall of rock fragments that were then recovered from the ground. These presented different appearance characteristics from those of the materials and rocks specific to the res...

In this research, we reported on the formation of highly porous foam SrTiO3/NiFe2O4 (100−xSTO/xNFO) heterostructure by joint solid-state and sol-gel auto-combustion techniques. The colloidal assembly process is discussed based on the weight ratio x (x = 0, 25, 50, 75, and 100 wt %) of NiFe2O4 in the 100−xSTO/xNFO system. We proposed a mechanism des...

Despite its great potential for thin films deposition and technological applications, the HiPIMS technology has its own limitations including the control of ion energy and flux towards the substrate when coping with the deposition of electrical insulating films and/or the deposition onto insulating/electrically grounded substrates. The bipolar-HiPI...

This work is focused on controlling and optimizing the inclusion of neon (Ne) and argon (Ar) impurities in tungsten (W) reference coatings. A tungsten target has been sputtered in monopolar and bipolar High Power Impulse Magnetron Sputtering (HiPIMS) operation modes, in Ar-Ne gas mixture. It has been found that the process of noble gas retention in...

Yb doped ZnO nanorods were prepared on glass substrates by the hydrothermal method in order to investigate the insertion of Yb ions in the ZnO matrix and the related morphological, structural and vibrational properties of the samples. X-ray diffraction patterns showed that the undoped and Yb doped ZnO nanorods exhibit the hexagonal wurtzite crystal...

In this paper, we report on the effect of titanium dioxide (TiO2) target sintering temper-18 ature on the morphological and optical properties of amorphous titanium dioxide thin films syn-19 thesized by pulsed laser deposition (PLD) on indium tin oxide (ITO) glass substrate and subse-20 quently heat-treated in air at low temperature (150 °C). Three...

In this paper, we report on the effect of titanium dioxide (TiO2) target sintering temperature on the morphological and optical properties of amorphous titanium dioxide thin films synthesized by pulsed laser deposition (PLD) on indium tin oxide (ITO) glass substrate and subsequently heat-treated in air at low temperature (150 °C). Three types of ta...

ZnO nanorods combined with different concentrations of reduced graphene oxide were synthesized using the hydrothermal method. Structural properties of these nanocomposites were studied by X-ray diffraction analysis. Morphological studies on the shape and size of nanorods were carried out by scanning electron microscopy. X-ray diffraction results re...

50 days' free access: https://www.sciencedirect.com/science/article/pii/S0921452621000375?dgcid=coauthor Nanoparticles with general formula CoFe2-xRExO4 (RE = Yb, Dy, Gd; x = 0.0–0.3) were synthesized by the co-precipitation and heat treated for potential application in magnetic hyperthermia. The influence of RE doping on structural, magnetic and...

Cobalt ferrite nanoparticles (NPs) doped with rare earth (RE) metals with general formula CoFe2-xRExO4 (RE=Yb, Dy, Gd; x = 0.0 - 0.3) were synthesized by the co-precipitation method followed by post thermal treatment. The influence of RE doping on structural, magnetic and thermal properties and potential biomedical applications like magnetic hypert...

In the herein paper, the possibility of obtaining spontaneous surface relief gratings (SSRGs) on azo-polymeric film surfaces, using a single laser beam of 1.13 mJ energy in pulse mode, was investigated. Chain rigidity is essential to have SSRG of reasonable quality so three azo modified polymers, with different main-chain rigidity, were considered:...

Two different polyimide structures were synthesized by two-step polycondensation reaction in solution, in the first step using equimolar amounts of one of two aromatic diamine (DDM or MMDA) and one dianhydride (6HDA) in N,N-dimethylacetamide (DMAc) to obtain the poly(amic acids), followed in the second step by thermal imidization. In order to obtai...

Transient plasmas generated by ns - laser ablation of graphite in air have been investigated by complementary optical diagnosis techniques to study complex multiple structures generated in carbon laser produced plasmas (C-LPP) during the expansion phase. The overall emission was investigated by ICCD fast camera imaging and revealed the structuring...

The properties of pulsed laser deposited of Ni60Ti40 shape memory thin films generated in various deposition conditions were investigated. In-situ plasma monitoring was implemented by means of space-and time-resolved optical emission spectroscopy, and ICCD fast camera imaging. Structural and chemical analyses were performed on the thin films using...

Several surface investigation techniques, such as X-ray diffraction (XRD), EDX, and optical microscopy, were employed in order to describe the mineral contents in several geomaterials. Space and time resolved optical emission spectroscopy was implemented to analyze the plasma generated by the laser–geomaterial interaction. The values of the plasma...

In our experiments, we propose an atmospheric pressure helium plasma technique as energy source for synthesis of thin (co)polymeric films using a mixture of monomers, especially selected to combine properties of individually polymers into a final (co)polymer film. Three combinations based on thiophene, 3,4-ethylenedioxythiophene and ethylene glycol...

The present study aims to demonstrate that operating the HiPIMS discharge in bipolar regime (BP-HiPIMS) enables an energy-enhanced deposition process of high-quality hydrogen-free DLC thin films (high hardness, low coefficient of friction, good wear resistance, good adherence to the substrate and very low surface roughness). The structural and mech...

The influence of rare earth (RE = Dy, Gd, Yb) ion doping on the structural, magnetic and optical properties of cobalt ferrite thin films was studied. CoFe2-xRExO4 (x = 0.01; 0.03; 0.05; 0.1; 0.2; 0.3) films were obtained by pulsed laser deposition on silicon substrates. The X-ray diffraction and Raman spectroscopy results on the bulk materials, whi...

Ge-Sb-Te thin films were obtained by ns-, ps-, and fs-pulsed laser deposition (PLD) in various experimental conditions. The thickness of the samples was influenced by the Nd-YAG laser wavelength, fluence, target-to-substrate distance, and deposition time. The topography and chemical analysis results showed that the films deposited by ns-PLD reveale...

A new method to produce keratin thin films using Pulsed Laser Deposition (PLD) is studied herein in order to obtain composite materials with application for medical purposes while being investigated α-keratin physico-chemical behavior during compared procedures. The novelty of the method consists in using direct wool fibers and horn bulk as targets...

Rapid solidification with high cooling rates of metal alloys determines both the improvement of mechanical properties, due to the finishing of the structure, as well as obtaining metastable structures in the form of supersaturated or amorphous/nano solid solutions, which could potentially confer the material outstanding properties. It is of particu...

The formation and dynamics of Al and Ag–Ni–Fe plasmas were studied through ICCD imaging and space- and time-resolved optical emission spectroscopy techniques. The experiments were conducted in pulsed laser deposition configuration and the surface topography and chemical composition of the obtained thin films were analyzed. For both targets, a split...

The problem of plasma self-structuring during the pulse laser deposition of multicomponent materials is discussed from both theoretical and experimental perspectives. A non-differential mathematical model was used to build the set of equation to characterize a complex fluid, assimilated with the laser produced plasmas in the fractal paradigm. Numer...

Ferrites are interesting magnetic materials with a wide applicability in current and emerging technologies. CoFe2O4 presents a high magnetostrictive response, important electrical resistivity, mechanical hardness and chemical stability making this material a suitable alternative for the development of sensors, actuators and magneto-optic devices. T...

The self-cleaning of the atmosphere under humidity conditions is observed due to the change in emission intensity when chemical traces are investigated with DARLIOES – the advanced LIDAR based on space- and time-resolved RAMAN and breakdown spectroscopy in conditions of consistent humidity of atmosphere. The determination was performed during the n...

DARLIOES - the advanced LIDAR is based on space- and time-resolved RAMAN and breakdown spectroscopy, to investigate chemical and toxic compounds, their kinetics and physical properties at high temporal (2 ns) and spatial (1 cm) resolution. The high spatial and temporal resolution are needed to resolve a large variety of chemical troposphere compoun...

The study of the interaction between acidophilic chemolithotrophic bacteria and heavy metal ions from minerals can occur through active and passive processes. The present of minerals in the solution and the need for metallic ions removal has opened two important ways to approach of the research. The adaptation of these bacteria to extreme environme...

Langmuir probe measurements were performed on transient plasmas generated by femtosecond laser ablation of several metallic targets (Al, Cu, Mn, Ni, In, Te, W). The analysis of current-voltage characteristics at various delays after the laser pulse gave access to the temporal evolution of ion density, electron temperature and plasma potential. The...

Mesoporous titanium dioxide was prepared by Evaporation Induced Self Assembly (EISA) method from titanium isopropoxide as precursor, and cetyl-trimethyl-ammonium bromide as surfactant. This sample was doped with cerium oxide by incipient wetness impregnation (IWI), using cerium ammonium sulfate. Two other samples of mesoporous TiO2 doped with ceriu...

The dynamics and properties of the (GeSe2)100-x(Sb2Se3)x laser-induced plasma were investigated by fast ICCD imaging and space- and time-resolved optical emission spectroscopy (OES). The experiments were performed at 10⁻⁶ Torr background pressure, using the second harmonic (532 nm) of the Nd-YAG laser (10 ns, 10 Hz). For all investigated samples, t...

The aim of this study is to synthesize and assess the potential applications of rare earth doped cobalt ferrite nanoparticles in cancer treatment through hyperthermia. The synthesis of CoFe2-xRExO4 (where RE= Yb, Dy, Gd and x=0.01-0.3) through the co-precipitation method is presented. The composition and properties of the nanoparticles where invest...

The effects of 90 keV neon beam irradiation on the structure and magnetic properties of zinc ferrite thin films have been investigated through several methods, namely, X-ray diffraction technique, Vibrating Sample and SQUID magnetometers. Beforehand, the pristine have also been characterized using profilometry and microscopy techniques. In particul...

Biodegradable alloys are very attractive biomaterials. Electrochemical impedance spectroscopy (EIS) and linear potentiodynamic polarization (LPP) techniques were used for the study of the electrochemical behavior of uncoated FeMnSi and coated FeMnSi with hydroxyapatite + zirconia (HA-ZrO2) through pulsed laser deposition (PLD) technique. Experiment...

We report on the generation of magnetic nanoparticles by nanosecond laser ablation of cobalt ferrite in liquid. We investigated the influence of both ablation liquid (water, ethanol, polyethylene glycol in water) and irradiation conditions (laser energy/pulse and spot size) on the nanoparticles dimension, shape, structure, chemical composition and...

Cobalt ferrite thin films with preferential crystallographic structure, controlled composition and perpendicular magnetic anisotropy can be obtained by pulsed laser deposition. Their properties are influenced by the experimental conditions and thus by the deposition plasma plume characteristics. The aim of this study was to obtain information on th...

To realize satisfactory fixation of hydroxyapatite (HA) and bio-functionality of bio-tolerated and bio-inert materials such as Ti6Al4V few physical surface modifications such as threaded surface through laser interactions have been produced to promote lung tissue and bone growth on a metallic material. Laser interaction with surface purposes are ba...

The study was focused on the influence of small amounts of rare earth (RE=La, Ce, Sm, Gd, Dy, Ho, Er, Yb) addition on the microstructure, phase content and magnetic properties of cobalt ferrite bulk materials. The X-Ray Diffraction measurements confirmed the formation of the spinel structure but also the presence of secondary phases of RE oxides or...

In this study, nano-silicon (Si) thin films were deposited on biodegradable Fe-1.5Mn-1Si substrate by pulsed laser deposition (PLD) method. Biodegradable metallic materials represent a good solution in implantology field based on the elimination of the second surgical operation required for the extraction of the material. Also, using biodegradable...

Physical and chemical properties of particles emitted by aircraft engines contribute to the variation of optical parameters of the entire atmospheric column. Since the properties of such particles vary in time and space, the correct identification of aerosol type is still difficult. Our work was focused on the influence of the aircraft plume on the...

Amorphous chalcogenide thin films are of high current interest for technological applications as optical storage media or waveguides for photonic integrated circuits. As part of a larger project including fs, ps and ns pulsed laser deposition regimes, Er- and Pr-doped GLS thin films were deposited by ns PLD, and their structural, chemical and optic...

Cobalt ferrite is a ferrimagnetic material with properties which support its use in different types of devices. In bulk form CoFe2O 4 presents the highest magnetostriction coefficient relative to other ferrites making it a good candidate for sensors and actuators. Due to the industries miniaturization trend, several research groups focused their st...

CoFe2O4 thin films with preferential texture structure, small grain size, and perpendicular magnetic anisotropy can be obtained by the pulsed laser deposition (PLD) technique. In this work, we studied the influence of the Fe3+ ions substitution by three elements from lanthanide group (Dy, La, and Gd) on the structural properties of the thin films....

Cobalt ferrite thin films are receiving increasing interest due to their high coercive field, high Curie temperature and chemical stability. Different values of the coercive field can be obtained by modifying the temperature of the substrate and the pressure of the O2 gas introduced in the chamber. For target ablation we used an excimer laser with...