NIMP| Mihaela Stegarescu, Author at NIMP

Publications

1. Preparation and properties of langasite and YAG amorphous films

Authors: Popescu, M; Sava, F; Lorinczi, A; Stegarescu, M; Georgescu, S; Mihailescu, IN; Socol, G; Stanoi, D; Daroczi, L; Kokenyesi, A; Leonovici, M; Wagner, D

Published: APR 2005, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 7, 966, DOI:

Amorphous thin films of langasite and YAG have been prepared from crystals targets by pulsed laser deposition, at room temperature, in vacuum, on silicon wafers. Bulges of micrometer size are formed on the film surface. Larger size bulges (10-50 micrometers in diameter) are characteristic to the annealed langasite films. Annealing at high temperatures leads to the crystallization of the films. The annealed langasite films (850 degrees C) are polycrystalline and partially oriented with the plane (001) parallel to the surface of the silicon wafer. The bulges break easily in the heat treated films. Their empty structure was remarked on the electron microscope images. The YAG films annealed at 1100 degrees C shows a crystalline YAG phase depleted in Y and traces of Y2O3. An interesting feature is the presence of silver particles spread along the macrodefects (fracture lines) of the film.

2. Influence of TiC deposition by cvd on Hartmetal type steel substrate

Authors: Stegarescu, M; Hoyer, W

Published: JUN 2004, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 6, 495, DOI:

The structure and properties (crystallographic phases, hardness) of Hartmetal-type steel we re investigated. The modification of the Hartmetal surface as a consequence of a special treatment with the purpose to improve the hardness by deposition of TiC films by chemical vapour deposition (CVD) was carefully analysed.

3. X-ray diffraction on cyanide-hardened iron plates

Authors: Popescu, M; Hoyer, W; Stegarescu, M; Cornet, A; Broll, N

Published: NOV 2004, JOURNAL DE PHYSIQUE IV, 118, 353, DOI: 10.1051/jp4:2004118041

4. Structure and properties of As25Te35Si40 glass

Authors: Popescu, M; Lorinczi, A; Sava, F; Stegarescu, M; Iovu, M; Leonovici, M; Halm, T; Hoyer, W

Published: OCT 1 2003, JOURNAL OF NON-CRYSTALLINE SOLIDS, 326, 393, DOI: 10.1016/S0022-3093(03)00444-7

The glassy composition As25Te35Si40 was investigated by microhardness, differential scanning calorimetry, X-ray diffraction, electrical conductivity and Raman spectroscopy measurements. A continuous random network model of the glass structure has been developed. (C) 2003 Elsevier B.V. All rights reserved.

5. Structure, properties and modelling of As25Te35Si40 glass

Authors: Popescu, MA; Lorinczi, AA; Sava, FA; Iovu, MB; Leonovici, MC; Stegarescu, MA; Halm, TD; Hoyer, WD

Published: 2002, XIIITH INTERNATIONAL SYMPOSIUM ON NON-OXIDE GLASSES AND NEW OPTICAL GLASSES PTS 1 AND 2, 84, DOI:

Glassy composition As25Te35Si40 was investigated by microhardness, differential scanning calorimetry, X-ray diffraction, electrical conductivity and Raman spectroscopy measurements. A continuous random network model of the glass structure has been developed.

6. Superconductor-ferroelectric heterostructures

Authors: Constantin, C; Ramer, R; Matei, I; Trupina, L; Stegarescu, M

Published: 1999, FERROELECTRICS, 225, 1092, DOI:

Superconductor-ferroelectric heterostructures were prepared by deposition of ferroelectric doped-PZT type material on the top of the superconductor YBCO thin films. Both, ferroelectric and superconductor thin films were obtained by off-axis RF magnetron sputtering method with a single target. On these heterostructures, measurements were made in order to evidence the influence of contact between the two materials on the electrical and thermal parameters. X-ray diffraction patterns of superconductor thin film show a good crystallization c-axis oriented perpendicular to the substrate plane, and a perovskite structure without traces of pyrochlore at 550 degrees C the ferroelectric thin film deposited by RF magnetron sputtering (off axis method). Important variations of the critical temperature of superconductor films have been obtained, due to the increased dielectric permittivity (epsilon).

Dr. Mihaela Stegarescu

Scientific Researcher