National Institute Of Materials Physics - Romania

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5781 articles found

1731. PRELIMINARY STRUCTURAL ULTRASONIC CHARACTERIZATION OF HYDROXYAPATITE

Authors: Popa, CL; Antohe, S; Safciuc, F; El Kettani, MEC; Leduc, D; Antohe, F; Predoi, MV

Published: JUL-SEP 2016, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 11, 1006, DOI:

Synthetic hydroxyapatite (HAp) is one of the most commonly used material for a large variety of biomedical applications. This paper presents structural, morphological and preliminary ultrasonic characterizations of the HAp nanopowder synthesized by an adapted co-precipitation method. To this end, the structural and morphological properties were evaluated by Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS). Biological investigation were also performed in order to evidence the influence of HAp tablets on the development and growth of endothelial cells. The ultrasonic measurements obtained for the HAp dispersion allowed us to calculate the ultrasonic velocity and the attenuation. The study of ultrasonic waves propagation through dispersions could be used as future standard quality test, thus improving the quality of biomedical devices based on hydroxyapatite.

1732. Local Ordering at the Interface of the TiO2-WO3 Bi-Layers

Authors: Macovei, D; Dascaleanu, V; Teodorescu, CM; Luca, D

Published: 2016, NANOSTRUCTURES AND THIN FILMS FOR MULTIFUNCTIONAL APPLICATIONS: TECHNOLOGY, PROPERTIES AND DEVICES, 331, DOI: 10.1007/978-3-319-30198-3_10

Reducing the recombination rate of photo-generated electron-hole pairs in the surface of pristine TiO2 materials can be done, among others, via local spatial charge separation in the photocatalytically active surface region. A local electric field acting for this purpose can be ensured, for instance, in hetero-junction regions formed at the interface between a TiO2 film and a WO3 ultra-thin layer. The option for the WO3-TiO2 semiconductor pair is related to the suitable fit of their band structures. To model the interface, a more in-depth knowledge of local atomic environment is required. Here, we discuss the local atomic ordering and the related effects in the interface region of TiO2/WO3 and WO3/TiO2 structures grown on Si (100) substrates. Materials characterization was done by using XRD, XPS and XAS techniques. We demonstrate that tungsten atoms enter as W6+ or W4+ cations into the rutile-type TiO2 lattice, by substituting the Ti4+ cations. While W6+-Ti4+ substitution leaves the surrounding rutile matrix unchanged, the W4+-Ti4+ substitution induces a local rutile-to-anatase transition. The current results are relevant in designing new applications structures with enhanced photocatalytic performances.

1733. Enamel Based Composite Layers Deposited on Titanium Substrate with Antifungal Activity

Authors: Iconaru, SL; Prodan, AM; Turculet, CS; Beuran, M; Ghita, RV; Costescu, A; Groza, A; Chifiriuc, MC; Chapon, P; Gaiaschi, S; Hristu, R; Stanciu, GA; Trusca, R; Ganciu, M; Raita, SM; Vineticu, N; Ciobanu, CS

Published: 2016, JOURNAL OF SPECTROSCOPY, 2016, DOI: 10.1155/2016/4361051

The goal of this paper was to investigate the antifungal activity of Enamel layers deposited on titanium substrate (Ti-Enamel) and Enamel layers deposited on titanium substrate previously coated with a vinyl polydimethylsiloxane layer (Ti-PDMS-Enamel). The physicochemical properties were also investigated. The Candida albicans biofilm development on the obtained layers was examined after 24 h, 48 h, and 72 h by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) after ethidium bromide staining. A significant inhibition of the fungal adherence and biofilm development was observed on Ti-Enamel layers. The antifungal results demonstrated that the use of new Ti-Enamel composite layers could represent a promising perspective for the prevention of fungal biofilms associated implant infections.

1734. LTCC-based Ceramic Microsystems with Integrated Fluidic Elements and Sensors

Authors: Belavic, D; Hodnik, M; Santo, M; Bolado, P; Ursic, H; Bradesko, A; Malic, B; Mercioniu, IF; Bencan, A; Makarovic, K; Ciobanu, RC; Schreiner, C

Published: 2016, PROCEEDINGS OF THE 2016 INTERNATIONAL CONFERENCE AND EXPOSITION ON ELECTRICAL AND POWER ENGINEERING (EPE 2016), 46, DOI: 10.1109/ICEPE.2016.7781299

In this contribution the design and fabrication of ceramic microsystems with integrated different microfluidic elements and sensors will be presented. Ceramic microsystems are based on unconventional application of low-temperature co-fired ceramic technology and materials. This unconventional application is related to three-dimensional ceramic structures, such as cantilevers, ledges, bridges, diaphragms, valleys, channels, holes and cavities, valves, mixers, diffusors, distributors, collectors, flow limiters, sensors, and actuators.

1735. Tailored electric and optical properties of Nd doped ZnO: from transparent conducting oxide to photon down-shifting thin films

Authors: Nistor, M; Mihut, L; Millon, E; Cachoncinlle, C; Hebert, C; Perriere, J

Published: 2016, RSC ADVANCES, 6, 41472, DOI: 10.1039/c6ra07669f

Nd-doped ZnO films with highly tunable properties were grown by pulsed electron beam deposition at 500 C on Si and c-cut single crystal substrates under oxygen gas. The effects of a slight change in the oxygen pressure (10(-2) to 2 x 10(-2) mbar) on the composition, structure and physical properties of the films were studied. Films grown at 10(-2) mbar present a low resistivity (5 x 10(-3) S-2 cm) and high transparency in visible range and do not show any near -infrared emission due to Nd3+ ions. On the contrary, films grown at 2 x 10(-2) mbar have high resistivity (>16 S-2 cm), high optical transparency and near infrared emission of the Nd3+ ions is observed under indirect excitation at 335 nm (i.e. absorption by the ZnO matrix and transfer to Nd3+ ions). These significant changes in physical properties, leading from transparent conducting oxide to photon down -shifting thin films, are related to growth mode in pulsed -electron beam deposition.

1736. XPS Analysis of AuGeNi/Cleaved GaAs(110) Interface

Authors: Negrila, CC; Lazarescu, MF; Logofatu, C; Cotirlan, C; Ghita, RV; Frumosu, F; Trupina, L

Published: 2016, JOURNAL OF NANOMATERIALS, 2016, DOI: 10.1155/2016/7574526

The depth composition of the thin layer alloy, AuGeNi, devoted to acting as an ohmic contact on n-GaAs(110) has been investigated by in situ XPS combined with Argon ion sputtering techniques. The fresh cleaved surfaces, supposed to be free of oxygen, were usually deposited with a 200nm metallic layer in high vacuum conditions (better than 10(-7) torr), by thermal evaporation, and annealed at a 430-450 degrees Celsius temperature for 5 minutes. About 18 sessions of ion Ar surfaces etching and intermediate XPS measurements were performed in order to reveal the border of the metal/semiconductor interface. The atomic concentrations of the chemical elements have been approximated. Au4f, Ga3d, Ga2p, As3d, As2p, Ni2p(3/2), Ge3d, O1s, and C1s spectral lines were recorded. The Au, Ge, and Ni have a homogenous distribution while Ga and As tend to diffuse to the surface. Oxygen is present in the first layers of the surface while carbon completely disappears after the second etching step. The existence of an Au-Ga alloy was detected and XPS spectra show only metal Ni and Ge within the layer and at the interface. We tried to perform a study about the depth chemical composition profile analysis of AuGeNi layer on cleaved n-GaAs(110) by X-Ray Photoelectron Spectroscopy (XPS) technique.

1737. INVESTIGATIONS ON THE PROPERTIES OF A TWO-DIMENSIONAL NANOPATTERNED METALLIC FILM

Authors: Breazu, C; Preda, N; Socol, M; Stanculescu, F; Matei, E; Stavarache, I; Iordache, G; Girtan, M; Rasoga, O; Stanculescu, A

Published: OCT-DEC 2016, Digest Journal of Nanomaterials and Biostructures, 11, 1229, DOI:

This paper presents some investigations of the effect of nanopatterning on the properties of aluminum layer deposited by sputtering. UV-Nanoimprint Lithography technique has been used for the realization of a 2D array of nanostructures (pillars) in aluminum film characterized by cylindrical shape and the following structural parameters: diameter between 400 nm and 490 nm, depth between 320 nm and 420 nm and periodicity of 1.1 mu m, which have been revealed by SEM and AFM measurements. The UV-Vis transmission, reflection and photoluminescence measurements have evidenced the effect of the nanopatterning on the optical properties of the A1 layer.

1738. Characterization of TiNi shape memory alloys obtained by spark plasma sintering process

Authors: Cirstea, CD; Tolea, F; Leonat, L; Lungu, M; Cucos, A; Cirstea, V; Tsakiris, V

Published: SEP-OCT 2016, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 18, 862, DOI:

This paper presents the research results on the thermal behavior of the 48.5% at Ti-Ni alloys, obtained by spark plasma sintering in vacuum under a pressure of 50 MPa, at temperatures of 850 degrees C and 900 degrees C and holding time of 5 minutes, and subsequently aged in argon for up to 30 minutes at 450 degrees C. Differential scanning calorimetry, dynamic mechanical and dilatometry analysis were used to characterize the transformation properties of the TiNi samples. All the results of differential scanning calorimetry and dynamic mechanical analysis confirmed the hypothesis that the stress-free thermally induced martensitic transformation exists in the investigated TiNi alloys. Annealing at lower temperatures (450 degrees C) in Ni-rich TiNi alloys led to precipitation process which facilitates the formation of the R-phase due to internal stress contributed by precipitates.

1739. An adamantane-based COF: stability, adsorption capability, and behaviour as a catalyst and support for Pd and Au for the hydrogenation of nitrostyrene (vol 6, pg 8344, 2016)

Authors: Trandafir, MM; Pop, L; Hadade, ND; Florea, M; Neatu, F; Teodorescu, CM; Duraki, B; van Bokhoven, JA; Grosu, I; Parvulescu, VI; Garcia, H

Published: 2016, CATALYSIS SCIENCE & TECHNOLOGY, 6, 8573, DOI: 10.1039/c6cy90113a

1740. MULTI-WAVELENGTH LASER IRRADIATION OF Be-C-W COATINGS

Authors: Avotina, L; Marcu, A; Porosnicu, C; Lungu, M; Stancalie, A; Ilie, AG; Ganea, PC; Savastru, D; Kalnacs, J; Lungu, CP; Kizane, G; Antohe, S

Published: JAN-MAR 2016, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 11, 302, DOI:

BeCW (3:2:1) amorphous films were irradiated with three laser wavelengths of 300, 550 and 1350 nm having a comparable energy and respectively power density. Ablated volume and preferential ablation of lighter elements seemed independent of the photon's energy, but rather on their number. Carbon and Be clustering and crystal formation into the amorphous coating were more effective with more energetic photons. Graphite structures formation was recorded for fluencies below the ablation threshold. For longer laser wavelengths, carbon atoms tend to organize in ring structures and fullerene formation was recorded around the ablation zones. Be crystals formed in the ablation zone vicinity tend to be stretched toward the film surface and toward the ablation center suggesting more defects into the formed structures for these zones.