Shema de realizare a proiectului 19 15 01 01 - Anul 2019 - Etapa a III-a

Faza nr. 23

Responsabil: Dr. I. Andrei

Termen de predare: 14.10.2019

Titlu: "Cercetari asupra laserilor acordabili cu mediu activ deformabil"

Abstract: In this phase, are studied the lasing properties of optofluidic systems such as liquid droplets of relatively large size which are in levitation. Data containing the characterization and optimization of the emission conditions of the lasing radiation of the individual deformable microvolummetric active media, containing laser dye solutions (Rh6G in water) are shown. The aim was to achieve a method of tuning the wavelength of the emission of deformable active media placed in an acoustic field. The tunability of the emission signal was achieved by increasing the intensity of the acoustic field so that the shape of the optical cavity/active medium was modified. The drops were generated using a medical syringe and were placed in an acoustic field, given by 72 ultrasonic translators, working at 40 kHz frequency. They were pumped with a laser beam at the wavelength of 532 nm, and the emission signal was analyzed by spectroscopic methods. It was observed a shift of the wavelength of the droplet emission towards the higher wavelengths as the acoustic field intensity increased.

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Faza nr. 24

Responsabil: Dr. M. Zamfirescu

Termen de predare: 14.10.2019

Titlu: "Producerea de fascicule de electroni accelerați la interacția pulsurilor laser ultraintense cu jeturi supersonice de gaze nobile"

Abstract: In this project phase, the experimental assembly for electron-beam acceleration at the CETAL-PW infrastructure was designed and realized. The objective of this stage was to prepare the experimental set-up for interaction of ultra-intense laser beams with gas-jets, in order to obtain accelerated electrons at energies of hundreds of MeV. Preliminary steps for obtaining electron beams at hundreds of MeV energy consisted of:
1) Optimization of laser beam parameters;
2) Implementation in the experimental assembly of the equipment for the generation and detection of accelerated electron beams;
3) Preliminary tests to verify the alignment of the acceleration system.
Ultra-intense femtosecond laser pulses have an extremely complex temporal and spatial structure and are sometimes difficult to control. Obtaining laser parameters compatible with the gas-jet electron acceleration method was a critical step to ensure the success of this kind of experiment. Parameters have been optimized, such as: the optical pulse duration by adjusting its stretcher-compressor components to the PW system, the spectral and spatial chirp by correcting the parallelism deviation of the diffraction gratings in the final compressor and most important, the wave front, respectively the focusability of the laser beam in the interaction chamber, by compensating the spatial phase distortions by a deformable mirror placed in the interaction chamber. After the purchase and installation of the deformable mirror compatible with the PW laser beam, a focal spot was obtained with dimensions near the diffraction limit, respectively a beam with a circular symmetry and a diameter of 35 um for the 3.2 m OAP focusing mirror (f/20).
The equipment for generating the synchronous gas jets with the laser pulse at variable pressures in the range 1-30 bars were mounted and tested in the interaction chamber. A wave front sensor (Phasics) was installed to determine the gas jet profile and gas density distribution (particles/cm3).
For detection of the accelerated electron beams, an extension of the PW interaction chamber was designed and installed. At the extremity of the extension tube, a device for real-time detection of electron beams was installed, with lanex film and triggerable video camera. In the interaction chamber, a permanent magnet electron spectrometer was installed, with the role of electron deflection up to energies of several hundreds of MeV,, to characterize their energy distribution.
The first preliminary tests of electron acceleration at laser powers of several TW were also performed, in order to verify the alignment of the focusing system with the gas-jet.

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a) Transverse distribution of the laser intensity at focus plan. Diameter of the focus is 35 um.
b) Mechanical protection of the nozzle used for generating the gas-jets.
c) Gaz-jet density distribution at various gas backing pression.
d) Laser induced plasma filament at 2 mm from the gas nozzle.


Faza nr. 25

Responsabil: Dr. D. Miu

Termen de predare: 14.11.2019

Titlu: "Depunerea laser si caracterizarea morfo-structurala a straturilor nanostructurate de Au pentru biosenzori"

Abstract: All of the objectives of the present research stage were attained: nanostructured Au thin films for biosensors were obtained by PLD (Pulsed Laser Deposition), and their morpho-structural properties were analyzed.
Au thin films were deposited by laser ablation in various conditions: deposition pressure, number of ablation pulses, target-substrate distance, energy/pulse. Depositions were made onto different substrates: on Si substrates for SEM microscopy, on quartz substrates or polymer (PMMA) deposited on quartz to replicate the conditions in which LW-SAW (Love Wave Surface Acoustic Wave) biosensors will be deposited. The morphology of the resulting structures was characterized by high-resolution electronic microscopy (Scanning Electron Microscopy – SEM and Atomic Force Microscopy – AFM).
In our deposition conditions the polymer layer (guiding layer for LW biosensors) is not affected by the Au layer (sensitive layer for LW biosensors) deposited onto it.
The morphology of the Au layers mainly depends on the deposition pressure and number of ablation pulses, and may thus be controlled. We have obtained structures varying from separate nanoparticles, to nanoparticle agglomerations of different dimensions, separated by cracks of varying widths, to extremely porous structures, depending on the deposition parameters. The dimensions of the cracks between the agglomerations vary from about 6 nm to about 25 nm, and are in the range of dimensions of pores characteristic for nanoporous Au successfully used in other types of biosensors, due to the compatibility with the dimensions of biological material.
The film roughness was determined by AFM. A dense uniform Au film deposited in vacuum has a surface roughness of 0.7 nm. Porous layers deposited in 4 Torr Ar have a roughness of 6 nm (deposited with 9800 ablation pulses) or 30 nm (30,000 pulses).
At larger target-substrate distances (8 cm), the structures obtained are characteristic for depositions with a smaller number of pulses at smaller distances (4cm).
All of the objectives for the present stage were attained, and the conditions for the next stage were created, namely the realization of Love Wave (LW) type SAW sensors based on nanostructured Au thin films as sensitive layers, and their characterization.
Two articles were published in Sensors and Actuators A and Journal of Sensors. An oral presentation was made at a conference (International Conference of Materials, Methods and Technologies 1-5 July 2019,Burgas, Bulgaria). A further article was accepted for publication in Sensors.

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Faza nr. 26

Responsabil: Dr. V. Craciun

Termen de predare: 14.11.2019

Titlu: "Modificarea structurii benzii interzisa a oxizilor metalici prin controlul presiunii de oxigen in timpul depunerii filmelor subtiri prin ablatie laser"

Abstract: A new method for determining the bandgap of metal oxides, MeOx, based on X-ray photoelectron excited spectroscopy has been studied and implemented in our research group in INFLPR. With respect to the traditional Tauc-Grigorovici optical method, this new method has the major advantage that it can be applied even to very thin films, down to 1-2 nm, deposited on any type of substrates, including opaque ones such as Si or Ge. Estimated values using this method for HfO2 and ZrO2 films deposited by pulsed laser deposition technique (PLD) under an oxygen atmosphere, whose stoichiometries were determined by non-Rutherford backscattering investigations, were found to be similar to those obtained using the Tauc-Grigorovici method for much thicker films. It was also observed that the value of the bandgap also depends on the stoichiometry of the oxide, which in turn depends on the value of the oxygen pressure used during the deposition. After an ionic treatment with Ar ions of 500 eV for several minutes, the measured value of the bandgap was lower than the initial value, most probably due to the reduction of the oxide due to the selective spraying of the oxygen atoms, much easier than those of Hf or Zr. This chemical reduction of the oxide was also confirmed by XPS measurements of Hf and O concentration.
Electrical and thermal conductivity measurements of zinc - indium oxide films showed that the values of electrical resistivity and thermal conductivity depend on the value of oxygen pressure used during deposition and are correlated according to the Wiedemann-Franz law. Also, spectral photoluminescence measurements on Y2O3 films: Bi2.0 mol%, Yb10.0 mol% indicated that the value of the oxygen pressure used during deposition influences the photoluminescence emission intensity.
In conclusion, the results obtained in this phase confirmed that:
a) value of oxygen pressure during pulsed laser deposition (PLD) affects stoichiometry of deposited films
b) Stoichiometry of films (metal / oxygen ratio) affects the electrical, thermal and optical properties of thin films.
c) PLD technique is extremely useful for studies regarding the links between stoichiometry-structure and physico-chemical properties of metallic oxide films.

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Faza nr. 27

Responsabil: Dr. Andrada Lazea-Stoyanova

Termen de predare: 14.11.2019

Titlu: "Caracterizarea procesului de producere a particulelor metalice in jet de plasma la presiune atmosferica"

Abstract: The purpose of this study was to obtain and characterize metallic particles, made out from a wide range of metals, using a plasma atmospheric pressure jet, and the characterization of the plasma-based synthesis process.
In order to understand the motivation behind the work, it should be mentioned that there is a general and a particular motivation. The general motivation is given by the global trend of the retail market for nanometric metallic particles, which indicate an increase from USD 12.35 billion in 2017 up to USD 25.26 billion in 2022 [1]. A similar increase is observed for the micrometric metal particles market [2]. This is determined by the continuous diversification of the applications in which metallic particles are involved, as a result of rapid industrialization and urbanization. Therefore, the synthesis of metallic particles represents an industrial field of great interest.
The particles were obtained using an atmospheric pressure radio frequency (RF) plasma jet. The used metal precursors were solid precursors. This study complets the range of materials used, so tht nickel, iron and chrome particles were produced. The particles were characterized by SEM/EDX apparatus. Investigations by optical emission spectroscopy were performed for plasma characterization, and measurement of process temperatures was done using a specially designed device. It is concluded that the RF power is an essential parameter that determines the characteristics of the particles (size, shape) and that the temperature measured at the grounded electrode/silicon substrate increases together with the increase of the applied power. However, the temperature increase does not have a liniar increasing behaviour along the applied RF power range.

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Faza nr. 28

Responsabil: Dr. M. Nistor

Termen de predare: 9.12.2019

Titlu: "Sinteza cu plasma a filmelor subtiri de oxizi pentru aplicatii in optoelectronica"

Abstract: Highly conducting and transparent Nd:ZnO thin films have been grown on c-cut sapphire substrates by pulsed electron beam deposition under argon (10-2 mbar). Such films grown at T > 300°C crystallize in the wurtzite structure, with well defined epitaxial relationships with the sapphire substrate. The improvement of the film structural quality with increasing growth temperature led to values of resistivities from 5.65 x 10-3 Ωcm at room temperature to 5.12 x 10-4 Ωcm at 500 °C with highest electron mobility and transparency


Faza nr. 29

Responsabil: Dr. O. Toma

Termen de predare: 9.12.2019

Titlu: "Sinteza si studiul de noi materiale oxidice pentru cresterea eficientei celulelor fotovoltaice"

Abstract: Ceramic TiO2 samples doped with erbium and ytterbium were synthesized by solid-state reaction, and nanocrystalline Er:Yb:TiO2 samples were synthesized by a sol-gel method. The structural properties of the samples were investigated by X-ray diffraction. The spectroscopic properties of the materials were investigated by optical spectroscopy (diffuse reflectance, upconversion-pumped luminescence, decay analysis). The nanocrystalline samples obtained by the sol-gel method have a more intense upconversion-pumped luminescence than the ceramic samples obtained by solid-state reaction.

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Faza nr. 30

Responsabil: Dr. A. Staicu

Termen de predare: 9.12.2019

Titlu: "Studiul spectroscopic al solutiilor de medicamente iradiate cu fascicul laser, supuse la conditii de hipergravitatie"

Abstract: In this stage, the comparative study of the optical properties by UV-VIS and FTIR spectroscopic methods was carried out before and after the exposure to hypergravity conditions (different gravity levels between 1 and 20 g) of some phenothiazine solutions: chlorpromazine, thioridazine, promazine and promethazine, unirradiated and irradiated with Nd: YAG laser beam emitted at 266 nm for different time intervals, between 0 and 4h.
Regarding the evolution in time of the absorption spectra in the UV-VIS spectral range of the phenothiazine solutions irradiated with laser beam, we could observe slight modifications of both sets of samples - non-centrifuged and subjected to hypergravity. It was pointed out that all centrifuged samples, especially those exposed for a longer time to laser radiation, spectra modifications exceed the limit of measurement errors, suffering a hypochromic effect. Advanced investigations (for samples launched in space) are needed to know whether this effect can be associated with the influence of high levels of gravity.
The analysis of FTIR spectra of the four phenothiazines indicates modifications at the molecular level of the initial compounds with the generation of photoproducts containing phenol and sulfoxide groups following exposure to laser radiation emitted in the UV spectral domain. This behavior was observed only for solutions with a concentration of 2 mg / mL. However, we noticed that all the solutions, both the irradiated ones and the ones that interacted with the laser beam, did not undergo molecular changes during the hypergravity conditions.

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Faza nr. 31

Responsabil: Dr. F. Dumitrache

Termen de predare: 9.12.2019

Titlu: "Prepararea de nanostructuri magnetice pe baza de fier folosind senzitivanti reactanti exotici in procese de piroliza cu laser"

Abstract: They were synthesized by laser pyrolysis and analyzed different iron-based nanoparticles: 1) N-doped Fe nanopowders, using the CO2 laser with λ = 10.74 µm; 2) B-doped Fe nanopowders using CO2 laser with λ = 10.59 µm; 3) Fe oxide nanopowders synthesized using ethanol vapor as a CO2 (O18) -9,245 µm laser sensitizer. Using the emission line 10P34- NH3 was optimally used as a sensitizing agent, obtaining powders predominantly with metallic Fe, Fe4N or FeN0.088 crystalline structure, they have an unusually high iron content (50-75 at%) and low oxygen content (23-37 at%), so that an important part of Fe bonds is presented as zerovalent iron, the rest being in the usual Fe2+ and Fe3+ ionization states. The process of laser pyrolysis involving the reactive mixture of Fe(CO)5 and B2H6 led to the formation of NPs with low crystallinity, depending on the amount of B incorporated, the particles preserving or not, zerovalent Fe. Using ethanol vapors as sensitizer for CO2 laser with λ = 9.245 µm, EDX analysis reveals the following elemental composition: 2.1 at% C, 35.5 at% Fe and 62.4 at.% O, so the Fe/O ratio is very close to 2/3 specific for γFe2O3.

Abstract grafic:

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Faza nr. 32

Responsabil: Dr. R. Cristescu

Termen de predare: 9.12.2019

Titlu: "Fabricarea filmelor subtiri de materiale compozite nanostructurate si functionalizate bazate pe nanoparticule magnetice multifunctionale de tip „core-shell” prin MAPLE pe diferite substraturi specifice metodei de investigare"

Abstract: Composite thin coatings of conductive polymer (polyaniline grafted lignin, PANI-LIG) embedded with aminoglycoside Gentamicin sulfate (SG) or magnetite nanoparticles loaded with SG (Fe3O4@SG) were deposited by the matrix-assisted pulsed laser evaporation (MAPLE) technique. In this first report: (a) we synthesized antibiotic-functionalized magnetite nanoparticles; (b) we prepared the MAPLE targets used in the deposition process; (c) we established the optimal parameters for obtaining an unaltered transfer of the initial biomaterials; d) the obtained films were characterized from a physico-chemical point of view: we obtained the non-altered quasi-stoichiometric transfer of the initial biomaterials (FTIR), hydrophilic films (wetability measurements) with a high corrosion resistance (electrochemical tests) and a weak crystalline nature (XRD); these thin films have showed a uniform incorporation of the magnetite and antibiotic particles in the polymeric matrix (SEM, AFM); (e) biological analyzes have shown that the composite coatings synthesized by MAPLE can provide effective protection against the development of microbial biofilms, without inducing any cytotoxicity to the MG-63 cells tested; (f) the efficiency of the depositing technique used has been proven. The aim was to obtain nanostructured titanium-based coatinSG for biomedical surfaces that could induce multi-functional properties to implantable devices, such as the controlled release of the therapeutically active substance under the action of a magnetic and/or electric field.

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Faza nr. 33

Responsabil: Dr. A. Groza

Termen de predare: 9.12.2019

Titlu: "Depuneri de straturi subtiri ceramice pe suporti polimerici prin tehnica de pulverizare magnetron in radio frecventa; Caracterizare structurala si morfologica"

Abstract: The results regarding the deposition of bioceramic layers of calcium phosphate on thermosensitive polymeric substrates in radio frequency magnetron discharges under different experimental conditions are presented. The steady state of the plasma and the optimum deposition parameters were identified by monitoring the temporal fluctuations of the deposition rate and by measuring the temperature at the polymeric substrate during the deposition process. Deposition plasma compositional analysis was performed by mass spectrometry.
The elemental and molecular structure of the coatings obtained on polymeric substrates determined by electron scattering spectroscopy and infrared spectroscopy with Fourier transform indicated the formation of an amorphous CaP structure. The morphological analyzes of the layers obtained by scanning electron microscopy and atomic force microscopy showed a thermal paterning of the substrate due to its heating during the deposition process. The CaP layers have a granular structure dependent on the pressure of the working gas.

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Faza nr. 34

Responsabil: Dr. C. Porosnicu

Termen de predare: 9.12.2019

Titlu: "Caracterizarea proprietatilor mecanice ale filmelor de WFeCr de interes pentu fuziunea termonulceara"

Abstract: EUROFER (9Cr-1W), represents the reference structural material for future DEMO reactors and the ITER test module. This study presents the characterization of new structural materials obtained by thin film alloys co-deposited on W and C substrate. The composite layers of W-Fe-Cr were co-deposited by the Thermionic Vacuum Arc method and were characterized basis on their structure, composition and mechanical properties.
XRF was applied in order to determine the concentration of the elements in each sample expressed in at. %, related to each anode distribution in the deposit chamber. Also, surface mapping was performed on each sample, proving a spatial distribution of element concentration on the investigated sample surface. SEM was used to investigate the surface morphology for co-deposits. Structural investigations were carried out using the XRD method. The nano-indentation and tribology methods were conducted in order to determine measurements of hardness and elastic modulus parameters. These investigations were performed to determine the influence of the thin film composition on the friction and hardness coefficients. Finally, the elementary depth and thickness profiles of each layer were determined using the GDOES method. Therefore, it was observed the distribution uniformity the elements in the volume of the thin layers.

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Faza nr. 35

Responsabil: Dr. D. Ighigeanu

Termen de predare: 9.12.2019

Titlu: "Materiale compozite pe bază de cauciuc natural şi amidon obţinute prin iradiere cu electroni acceleraţi"

Abstract: The phase objective was the development of some vulcanization/cross-linking methods by electron beam irradiation, applicable to elastomeric composites, using natural materials as fillers. The composites stability in accelerated electrons field and corrosive environments was tested.
In order to evaluate the composites resistance in accelerated electron beams, were irradiated at 150 kGy, 300 kGy and 450 kGy samples of Nr/St (natural rubber/starch) type. Starch loading was between 10 and 50 phr. Before and after irradiation, mechanical, physical, chemical and structural analysis were carried out. Were realized absorption tests in water and corrosive solutions (synthetic oil, sulfuric acid and sodium hydroxide 50%) at 23 ± 2 °C. For the quantitative evaluation of grafting efficiency and chains braking (degradation), was calculated the ratio between degradation and cross-linking densities (p0 /q0) by applying Charlesby-Pinner equation. The ratio p0/q0 must be under unit for a stable material in radiation field. The obtained results were of 0.1365, 0.1291, 0.1253, 0.1164 and 0.1440 for starch loadings of 10, 20, 30, 40 and 50 phr, respectively. These results, corroborate with mechanical properties variation, demonstrate that materials of NR/St type can be used in accelerated electrons field up to 450 kGy.
The development of some vulcanization/cross-linking methods by electron beam irradiation consisted in the obtaining of composites materials based on EPDM rubber and wood sawdust, as filler. The irradiation doses were between 75-600 kGy and filler concentration between 5 and 50 phr. Mechanical, physical, chemical and structural analysis were also carried out. The mechanical tests results demonstrated the positive effect of filler loading. The variation of these properties with irradiation dose is due to the cross-linking between elastomeric chains and also, to filler grafting on polymeric chains. Low values of p0/q0 ratio (of 0.1148, 0.0889, 0.0812 and 0.1204 for 5, 10, 15 and 20 phr of sawdust in the mixture) are associated with an improved radical-radical interaction in the composite.

Abstract grafic:

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Faza nr. 36

Responsabil: Dr. M. Filipescu

Termen de predare: 9.12.2019

Titlu: "Stabilire model de heterostructuri bazate pe oxizi si silicati metalici (oxid de hafniu, oxid de aluminu, silicat de hafniu, silicat de aluminiu); determinarea parametrilor experimentali optimi pentru obtinerea de heterostructuri prin PLD si RF-PLD"

Abstract: Nowadays, the antireflective coatings exhibiting high damage threshold are intensively studied due to the development of high power ultra-short pulse lasers.
In this work we report the deposition and characterization of antireflective (AR) coatings based on dielectric oxides thin films for high power laser optics. The Al2O3, SiO2, and HfO2 thin films combined in heterostructures with 5 and 7 layers have been obtained in controllable oxygen atmosphere, at high temperatures (600 ˚C) on quartz substrates, by pulsed laser deposition (PLD) and radio-frequency assisted pulsed laser deposition (RF-PLD). The targets were irradiated with 266 nm wavelength.
Also, hafnium silicate and aluminium silicate are considered potential dielectric materials for antireflective coatings. These materials were obtain as thin films (single-layers) by irradiation of metal oxides target with different wavelength (193 nm and 1064 nm) in 0.01 mbar of oxygen; the substrate was heated at 600 ˚C during the depositions.
Atomic force microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and spectro-ellipsometry techniques were used to investigate the properties of the obtained samples.
Smooth, uniform, low-roughness HfSixO1-x and AlSixO1-x layers were obtained when λ = 193 nm and Φ = 1 J/cm2. Both the percentage of HfO2 and the percentage of Al2O3 embedded in the corresponding silicate layer are influenced by the value of the laser fluence used. Higher laser fluence induces a higher concentration of hafnium oxide or aluminum oxide in the layers.
Multi-layer structures based on HfO2/Al2O3 and HfO2/SiO2 have uniform surfaces, with a low roughness value, without micro- or nano-metric cracks. Also, on the surfaces of all the analyzed films, "grains"-like formations rarely distributed, with dimensions of hundreds of nanometers were identified. The thickness of the heterostructures evaluated using ellipsometry was about 800 nm.


Faza nr. 20b

Responsabil: Dr. I. Tiseanu

Termen de predare: 9.12.2019

Titlu: "Analiza cantitativă a caracteristicilor pulberilor metalice și a porozității componentelor realizate prin manufacturare aditivă prin microtomografie de raze X și procesare de imagini. Comparație cu analiza 2D a imaginilor metalografice - partea II - Comparație cu analiza 2D"

Abstract: The main activity carried out in this phase consisted of non-destructive analysis of 3D printed parts by X-ray tomography and the application of advanced software modules for defectoscopy and metrology (VGstudi MAX vs Avizo). A 3D printer was used to make polymer test samples with varying degrees of filling. Visual comparisons were made of the virtual sections through 3D reconstructions with the optical images of some sections extracted by destructive analysis and the differences of internal structure based on the different filling factor were confirmed. The filling factor was evaluated by different algorithms from the main commercial software packages: VGstudio Max and Avizo. Additionally, binarization procedures applied to the reconstructions within the Avizo program have been demonstrated. These can be applied to perform mechanical simulations on the investigated parts.

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