National Institute Of Materials Physics - Romania

Publications

5781 articles found

1901. Microstructure and properties of epitaxial Sr2FeMoO6 films containing SrMoO4 precipitates

Authors: Deniz, H; Preziosi, D; Alexe, M; Hesse, D; Eisenschmidt, C; Schmidt, G; Pintilie, L

Published: APR 2015, JOURNAL OF MATERIALS SCIENCE, 50, 3138, DOI: 10.1007/s10853-015-8874-7

Thin films of Sr2FeMoO6 (SFMO) were grown by pulsed laser deposition in non-optimized argon ambient pressures. The films were found to contain a high number of precipitates of foreign phases. The nature and microstructure of these phases were investigated in detail by high-resolution scanning transmission electron microscopy (STEM) and X-ray diffractometry (XRD). We found out that the dominant foreign phase embedded in the SFMO film matrix was SrMoO4 (SMO). Through STEM and XRD analysis, we determined that the SMO phase grows epitaxially with respect to the surrounding SFMO matrix and has a fairly good crystallinity. Although the SFMO films include many foreign precipitates, they still exhibit good conducting properties and moderate magnetization values. Tuning the growth of the SMO phase on top of SFMO films to obtain a natural tunnel barrier might pave the way for future applications of SFMO in spintronic devices.

1902. Dry reforming of methane on ceria prepared by modified precipitation route

Authors: Rotaru, CG; Postole, G; Florea, M; Matei-Rutkovska, F; Parvulescu, VI; Gelin, P

Published: MAR 25 2015, , DOI: 10.1016/j.apcata.2015.01.024

1903. Effect of counterion on the mesomorphic behavior and optical properties of columnar pyridinium ionic liquid crystals derived from 4-hydroxypyridine

Authors: Pana, A; Badea, FL; Ilis, M; Staicu, T; Micutz, M; Pasuk, I; Circu, V

Published: MAR 5 2015, JOURNAL OF MOLECULAR STRUCTURE, 1083, 251, DOI: 10.1016/j.molstruc.2014.11.059

A series of 3,4,5-tridodecyloxybenzyl pyridinium salts derived from 4-hydroxypyridine has been designed and prepared. The liquid crystalline properties of these compounds were investigated by polarized optical microscopy, differential scanning calorimetry and powder X-ray diffraction while their thermal stability was studied by thermogravimetric analysis. The N-3,4,5-tridodecyloxybenzyl-4-pyridone intermediate shows a monotropic columnar hexagonal mesophase ranging from 56 degrees C down to room temperature while the corresponding bromide dodecyl O-alkylated pyridinium salt shows one enantiotropic columnar mesophase and one additional monotropic columnar phase at lower temperatures. Replacing bromide ion (Br-) with other counterions (NO3-, BF4- and PF6-) resulted in mesophase suppression. These luminescent pyridinium salts show weak emission in dichloromethane solutions at room temperature and a pronounced red-shifted emission in solid state. Photoluminescent properties of the pyridinium salts do not depend significantly on the nature of counterion employed. (C) 2014 Elsevier B.V. All rights reserved.

1904. Thin films of amorphous Ga2S3 and rare-earth sulphides

Authors: Popescu, M; Lorinczi, A; Sava, F; Velea, A; Simandan, ID; Badica, P; Burdusel, M; Galca, AC; Socol, G; Jipa, F; Zamfirescu, M

Published: MAR 1 2015, MATERIALS LETTERS, 142, 231, DOI: 10.1016/j.matlet.2014.12.028

The aim of this research is to prepare amorphous thin films of undoped gallium sulphide and doped with rare-earth sulphides, of rare-earth sulphides and to investigate their physical properties. We have prepared thin amorphous films of Ga2S3, EuS, Er2S3, Gd2S3, and Ga2S3 doped with rare-earth sulphides (Ga2S3:EuS, Ga2S3:Er2S3, Ga2S3:Gd2S3) by Pulsed laser Deposition (PLD). The corresponding targets for preparation of amorphous thin films were obtained by Spark Plasma Sintering (SPS) from commercially available powders of binary sulphides. The structural results for the undoped and doped Ga2S3 thin films indicate a packing of disordered layers similar to that of amorphous As2S3. Femtosecond laser irradiation of the Ga2S3 thin films shows a photoexpansion effect at low laser power (85-100 mW) and an ablation effect at higher laser power (above 105 mW). The threshold between low power and high power pulses is situated at higher value for Ga2S3 (100 mW) in comparison with the case of As2S3 thin films (20 mW). (C) 2014 Elsevier B.V. All rights reserved.

1905. Biomimetic nanocrystalline apatite coatings synthesized by Matrix Assisted Pulsed Laser Evaporation for medical applications (vol 181, pg 56, 2014)

Authors: Visan, A; Grossin, D; Stefan, N; Duta, L; Miroiu, FM; Stan, GE; Sopronyi, M; Luculescu, C; Freche, M; Marsan, O; Charvillat, C; Ciuca, S; Mihailescu, IN

Published: MAR 2015, MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS, 193, 206, DOI: 10.1016/j.mseb.2014.10.011

1906. Applicability of the Stoner-Wohlfarth Model for Ni-Fe Graded Thin Films

Authors: Kuncser, A; Schinteie, G; Ghica, C; Antohe, S; Kuncser, V

Published: MAR 2015, JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM, 28, 969, DOI: 10.1007/s10948-014-2684-z

Fe-Ni graded films have been prepared by co-sputtering permalloy and Fe targets at different time-power sequences. Morpho-structural and magnetic investigations have been performed by transmission electron microscopy, Xray reflectometry, conversion electron Mossbauer spectroscopy and magneto-optic Kerr effect vector magnetometry, proving the thickness dependence of the properties. A magnetization reversal involving the displacement of Bloch-type walls is characteristic for a 115 nm thick Fe-Ni graded film whereas an in-plane coherent rotation of the spins, according to a Stoner-Wohlfarth mechanism was evidence for a 23 nm thick Fe-Ni graded film.

1907. Fabrication of magnetite-based core-shell coated nanoparticles with antibacterial properties

Authors: Grumezescu, AM; Cristescu, R; Chifiriuc, MC; Dorcioman, G; Socol, G; Mihailescu, IN; Mihaiescu, DE; Ficai, A; Vasile, OR; Enculescu, M; Chrisey, DB

Published: MAR 2015, BIOFABRICATION, 7, DOI: 10.1088/1758-5090/7/1/015014

We report the fabrication of biofunctionalized magnetite core/sodium lauryl sulfate shell/antibiotic adsorption-shell nanoparticles assembled thin coatings by matrix assisted pulsed laser evaporation for antibacterial drug-targeted delivery. Magnetite nanoparticles have been synthesized and subsequently characterized by transmission electron microscopy and x-ray diffraction. The obtained thin coatings have been investigated by FTIR and scanning electron microscope, and tested by in vitro biological assays, for their influence on in vitro bacterial biofilm development and cytotoxicity on human epidermoid carcinoma (HEp2) cells.

1908. Ferromagnetic behaviour of bismuth germanate oxides glass-ceramic materials

Authors: Polosan, S; Negrea, R; Ciobotaru, IC; Schinteie, G; Kuncser, V

Published: FEB 25 2015, JOURNAL OF ALLOYS AND COMPOUNDS, 623, 196, DOI: 10.1016/j.jallcom.2014.10.104

The content of defects in Bi4Ge3O12 (BGO) glass-ceramic materials together with their ordering during crystallization induces ferromagnetic behaviours in these materials. The observed ferromagnetism has to be associated strictly with the GeO4 related defects in the atypical amorphous phase. The photoluminescence of BGO glass-ceramic materials can give useful information about the nature of defects, especially the oxygen vacancies from the GeO4 tetrahedra and Bi4Ge3O12 cubic structures. The concentration of these defects depends on annealing between 600 degrees C and 700 degrees C where orthorhombic and cubic phases coexist. The magnetization at saturation is higher in the samples dominated by the amorphous phase and the strength of the exchange interaction is higher in the samples dominated by the cubic phase, obtained over 700 degrees C, when the GeO4 tetrahedra are rearranged during crystallization together with their oxygen vacancies. (C) 2014 Elsevier B.V. All rights reserved.

1909. New coordination polymers with chromato bridges: (1)(infinity)[Ni(phen)(H2O)(2)(mu-O2CrO2)] and (3)(infinity)[Mn(4,4 '-bipy)(H2O)(mu-O3CrO)]center dot H2O

Authors: Dumbrava, A; Olar, R; Badea, M; Maxim, C; Ghica, D; Andruh, M

Published: FEB 24 2015, INORGANICA CHIMICA ACTA, 426, 54, DOI: 10.1016/j.ica.2014.11.009

Two new coordination polymers have been assembled using the chromato ions as bridging ligands: (1)(infinity)[Ni(phen)(H2O)(2)(mu-O2CrO2)] 1, and (3)(infinity)[Mn(4,4'-bipy)(H2O)(mu-O3CrO)]center dot H2O 2. In crystal 1 the chromate ions act as bridges connecting two nickel ions through two oxygen atoms, resulting in infinite chains. 1,10-Phenanthroline acts as a blocking ligand. In compound 2, each chromato ion is connected to three manganese ions, resulting in layers which are parallel to the ab plane. The layers are constructed from {Mn3Cr3} meshes, each metal atom being shared between three other meshes. The structure is expanded into the third direction by connecting the inorganic layers through 4,4'-bipy spacers. The thermal decomposition of the two compounds has been investigated. (C) 2014 Elsevier B.V. All rights reserved.

1910. Out of plane superferromagnetic behavior of quasi two-dimensional Fe/Al2O3 multilayer nanocomposites

Authors: Miu, DN; Jinga, SI; Vasile, BS; Miu, L

Published: FEB 21 2015, JOURNAL OF APPLIED PHYSICS, 117, DOI: 10.1063/1.4908219

The magnetic properties of low filling factor Fe-nanoparticle monolayers separated by relatively thick Al2O3 layers were investigated in parallel and perpendicular external magnetic field. The thin film nanocomposites were prepared by sequential pulsed laser deposition on (100) Si substrates, and the monolayers contain single-domain, dispersive nanoparticles. When the magnetic field is oriented parallel to the layers, the composite exhibits superparamagnetism. However, in perpendicular field, the superferromagnetic order sets in, as revealed by the increase of the magnetic moment, the hysteresis persisting at high temperatures, and a smaller relaxation rate. The complex out of plane behavior of our nanocomposites in perpendicular field is attributed to quasi two-dimensionality and to the dispersion of the in-plane nanoparticle separation. (C) 2015 AIP Publishing LLC.