National Institute Of Materials Physics - Romania

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5781 articles found

2191. Structural Characterization of Impurified Zinc Oxide Thin Films

Authors: Trinca, LM; Galca, AC; Stancu, V; Chirila, C; Pintilie, L

Published: 2014, ELECTROCERAMICS XIV CONFERENCE, 1627, 128, DOI: 10.1063/1.4901669

Europium doped zinc oxide (Eu:ZnO) thin films have been obtained by pulsed laser deposition (PLD). 002 textured thin films were achieved on glass and silicon substrates, while hetero-epilayers and homo-epilayers have been attained on single crystal SrTiO3 and ZnO, respectively. X-ray Diffraction (XRD) was employed to characterize the Eu:ZnO thin films. Extended XRD studies confirmed the different thin film structural properties as function of chosen substrates.

2192. SYNTHESIS AND CHARACTERIZATION OF GLASS-CERAMIC SUPERCONDUCTORS IN (Pb, B)-DOPED Bi-Sr-Ca-Cu-O SYSTEM

Authors: Fruth, V; Tanase, G; Atkinson, I; Pandele Cusu, J; Aldica, G; Zaharescu, M

Published: JUN-JUL 2014, REVUE ROUMAINE DE CHIMIE, 59, 383, DOI:

Glass-ceramic superconductors in the Bi-Sr-Ca-Cu-O system were prepared by melt-quenching method in the presence of some additives (Pb, B). The studied glasses were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (DTA/TGA) and differential scanning calorimetry (DSC). On the crystallized ceramics obtained by the annealing the glasses, transport resistance and XRD measurements were also done. The glass transition temperatures (T-g) was found to range in the 380-430 degrees C domain, followed by a set of exothermal effects that could be assigned to the crystallization of the superconducting phases. The nucleation and growth of the crystals is influenced by both the nature of the oxides used as additives and by their ratio. So, the samples doped with low amount of B (x=0.1 and 0.2) present obvious transitions at about 110 K, highlighting the presence of the 2223 phase in highest amount and well interconnected.

2193. Stress Influenced Trapping Processes in Si Based Multi-Quantum Well Structures and Heavy Ions Implanted Si

Authors: Ciurea, ML; Lazanu, S

Published: 2014, INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2014 (ICCMSE 2014), 1618, 63, DOI: 10.1063/1.4897674

Multi-quantum well structures and Si wafers implanted with heavy iodine and bismuth ions are studied in order to evaluate the influence of stress on the parameters of trapping centers. The experimental method of thermostimullatedcurrents without applied bias is used, and the trapping centers are filled by illumination. By modeling the discharge curves, we found in multilayered structures the parameters of both 'normal' traps and 'stress-induced' ones, the last having a Gaussian-shaped temperature dependence of the cross section. The stress field due to the presence of stopped heavy ions implanted into Si was modeled by a permanent electric field. The increase of the strain from the neighborhood of I ions to the neighborhood of Bi ions produces the broadening of some energy levels and also a temperature dependence of the cross sections for all levels.

2194. Zinc Oxide and Polysaccharides: Promising Candidates for Functional Nanomaterials

Authors: Preda, N; Enculescu, M; Zgura, I; Socol, M; Florica, C; Evanghelidis, A; Matei, E; Enculescu, I

Published: 2014, SIZE EFFECTS IN NANOSTRUCTURES: BASICS AND APPLICATIONS, 205, 136, DOI: 10.1007/978-3-662-44479-5_5

Recently, ZnO and natural polysaccharides have received more and more attention as interesting components for designing complex functional nanomaterials, key elements being their high occurrence and low-cost. In this chapter are presented possibilities for tailoring the ZnO properties by using polysaccharides in the synthesis process as well as reports on the functionalization of cellulose-based natural fabrics with ZnO. In both cases, in the preparation step were used only simple and scalable wet chemical methods. The resulting materials with suitable characteristics, e.g. dependence of the ZnO nanostructures optical properties on their morphology or high-UV blocking and superhydrophobicity for ZnO-functionalized fabrics, can find applications in domains where such qualities are required.

2195. Boundary conditions effect on states and transitions in a quantum-well - nanobridge - quantum dot structure

Authors: Goray, LI; Racec, PN

Published: 2014, PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON 2014 DAYS ON DIFFRACTION (DD), 95, DOI:

We consider a varied-dimension InGaAs/GaAs structure of quantum well - nanobridge (NB) - quantum dot embedded in a "virtual" cylinder Omega. Electron and hole eigenstates are computed for the whole system using the finite volume method and effective mass approximation. Hybrid states and significant oscillator strength changes appear in the combined system at small values of the NB length under the Dirichlet boundary conditions imposed on the boundaries of Omega.

2196. High-Order Modes in High Permittivity Cylindrical Dielectric Resonator Antenna Excited by a Wide Microstrip Line

Authors: Avadanei, OG; Banciu, MG; Nedelcu, L

Published: 2014, 2014 10TH INTERNATIONAL CONFERENCE ON COMMUNICATIONS (COMM), DOI:

The aim of the paper is to identify the modes that can be excited by a wide microstrip line, in a cylindrical DRA situated symmetrically above it, to study the radiating performances of these modes and to present their radiating patterns. We managed to identify thirteen high-order modes; among these modes, four of them: HEM112, TMme(311), TEme(112), and TEme(121) have high transmission performances.

2197. DRUG DELIVERY STUDY OF SINGLE-WALL CARBON NANOTUBES COVALENT FUNCTIONALIZED WITH CISPLATIN

Authors: Ciobotaru, CC; Damian, CM; Polosan, S; Prodana, M; Iovu, H

Published: APR-JUN 2014, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 9, 868, DOI:

Carbon nanotubes are widely studied components for drug delivery systems due to their high surface area and low chemical reactivity. The research presented in this paper deals with the synthesis of drug delivery systems based on single walled carbon nanotubes (SWCNTs) and the well-known cancer treatment drug Cisplatin. The new nanomaterials obtained through covalent bonding between carboxyl groups from the SWCNTs surface and amino groups from the Cisplatin structure were characterized from structural point of view. To evaluate the content of drug released the Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was employed. The releasing profile shows a slow rate in the beginning followed by a spectacular increase after 180 minutes which means that this type of system could be used for prolonged release.

2198. Luminescent liquid crystalline materials based on palladium(II) imine derivatives containing the 2-phenylpyridine core

Authors: Micutz, M; Ilis, M; Staicu, T; Dumitrascu, F; Pasuk, I; Molard, Y; Roisnel, T; Circu, V

Published: 2014, DALTON TRANSACTIONS, 43, 1161, DOI: 10.1039/c3dt52137k

In this work we report our studies concerning the synthesis and characterisation of a series of imine derivatives that incorporate the 2-phenylpyridine (2-ppy) core. These derivatives were used in the cyclo-metalating reactions of platinum(II) or palladium(II) in order to prepare several complexes with liquid crystalline properties. Depending on the starting materials used as well as the solvents employed, different metal complexes were obtained, some of them showing both liquid crystalline behaviour and luminescence properties at room temperature. It was found that, even if there are two competing coordination sites, the cyclometalation process takes place always at the 2-ppy core with (for Pt) or without (for Pd) the imine bond cleavage. We successfully showed that it is possible to prepare emissive room temperature liquid crystalline materials based on double cyclopalladated heteroleptic complexes by varying the volume fraction of the long flexible alkyl tails on the ancillary benzoylthiourea (BTU) ligands.

2199. MICROSTRUCTURE OF THE a-C: H/W LAYERS DEPOSITED BY PLASMA ASSISTED SEQUENTIAL DEPOSITION METHOD

Authors: Acsente, T; Negrea, RF; Lazea-Stoyanova, A; Nistor, LC; Dinescu, G

Published: APR-JUN 2014, DIGEST JOURNAL OF NANOMATERIALS AND BIOSTRUCTURES, 9, 450, DOI:

A study regarding the microstructure of a-C: H/W mixed materials deposited by plasma assisted sequential deposition method is presented. The deposition of layers was performed by cyclic exposing a substrate, for predefined time intervals, to two deposition processes, working in alternative sequences: Magnetron Sputtering (MS) for metal deposition and Plasma Enhanced Chemical Vapor Deposition (PECVD) for carbon deposition. During the deposition the plasma parameters were kept constant while the durations of the individual MS and PECVD steps were systematically modified. The deposited samples were investigated using both transmission and scanning electron microscopy methods. Nanocomposite structures are obtained if each metal deposition step is interrupted in the island stage of the layer formation followed by coverage with a continuous layer of carbon. Multilayer structures are obtained when the full development of a continuous metallic layer is allowed. The spatial periodicity of the multilayers can be adjusted in between tens and hundreds of nanometers by proper setting the duration of substrate exposure to plasma sources.

2200. AZO THIN FILMS SYNTHESIZED BY RF-MAGNETRON SPUTTERING: THE ROLE OF DEPOSITION POWER

Authors: Besleaga, C; Ion, L; Antohe, S

Published: 2014, ROMANIAN REPORTS IN PHYSICS, 66, 1001, DOI:

Transparent c-axis textured aluminum doped zinc oxide (AZO) films were deposited at room temperature onto glass substrates by radio-frequency magnetron sputtering. The effect of sputtering power on the properties of the AZO sputtered thin films was investigated. Our results indicated that the sputtering power has a great influence on the crystalline quality and electrical parameters of AZO films, thus being a useful tool for tuning their functional properties.