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MgO Substrates (mgo + substrate)

Distribution by Scientific Domains
Physics and Astronomy50%

Selected Abstracts

Fabrication and Electrochemical Properties of Epitaxial Samarium-Doped Ceria Films on SrTiO3 -Buffered MgO Substrates

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2009
Simone Sanna
Abstract Thin films of samarium-oxide-doped (20,mol%) ceria (SDC) are grown by pulsed-laser deposition (PLD) on (001) MgO single-crystal substrates. SrTiO3 (STO) prepared by PLD is used as a buffer layer on the MgO substrates to enable epitaxial growth of the fluorite-structured SDC film; the STO layer provides a proper crystalline match between SDC and MgO, resulting in highly crystalline, epitaxial SDC films grown in the (001) orientation. Film conductivity is evaluated by electrochemical impedance spectroscopy measurements, which are performed at various temperatures (400,775,°C) in a wide range of oxygen partial pressure (pO2) values (10,25,1,atm) in order to separate ionic and electronic conductivity contributions. At 700,°C, SDC/STO films on (100) MgO exhibit a dominant ionic conductivity of about 7,×,10,2,S cm,1, down to pO2 values of about 10,15,atm. The absence of grain boundaries make the SDC/STO/MgO heterostructures stable to oxidation-reduction cycles at high temperatures, in contrast to that observed for the more disordered SDC/STO films, which degraded after hydrogen exposure. [source]

A comparative ab initio study of Cu overlayers on BaTiO3(001) and MgO(001) substrates

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2008
Yu. F. Zhukovskii
Abstract In order to compare Cu adhesion upon two kinds of perfect cubic (001) oxide surfaces: (i) TiO2 - and BaO-terminated substrates of partly covalent BaTiO3 and (ii) highly ionic MgO substrate, we have performed DFT-LCAO calculations using a hybrid B3PW Hamiltonian. 2D symmetrical slabs used here contain seven BaTiO3 and five MgO substrate layers covered on both sides by submonolayers of ordered Cu atoms. The Cu periodic coverage density atop the surface oxygen anions was varied from 1/8 to 1/2 monolayer. Copper bonding on the BaTiO3(001) surface has been found to be noticeably stronger than that on ionic MgO(001). Cu adatoms attract the electron density from BaO-terminated and donate it towards TiO2 -terminated BaTiO3(001) substrates, respectively, by an amount that is about threefold larger than for a Cu/MgO(001) interface. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Low-Temperature Superionic Conductivity in Strained Yttria-Stabilized Zirconia

ADVANCED FUNCTIONAL MATERIALS, Issue 13 2010
Michael Sillassen
Abstract Very high lateral ionic conductivities in epitaxial cubic yttria-stabilized zirconia (YSZ) synthesized on single-crystal SrTiO3 and MgO substrates by reactive direct current magnetron sputtering are reported. Superionic conductivities (i.e., ionic conductivities of the order ,1 ,,1cm,1) are observed at 500,°C for 58-nm-thick films on MgO. The results indicate a superposition of two parallel contributions , one due to bulk conductivity and one attributable to conduction along the film,substrate interface. Interfacial effects dominate the conductivity at low temperatures (<350,°C), showing more than three orders of magnitude enhancement compared to bulk YSZ. At higher temperatures, a more bulk-like conductivity is observed. The films have a negligible grain-boundary network, thus ruling out grain boundaries as a pathway for ionic conduction. The observed enhancement in lateral ionic conductivity is caused by a combination of misfit dislocation density and elastic strain in the interface. These very high ionic conductivities in the temperature range 150,500,°C are of great fundamental importance but may also be technologically relevant for low-temperature applications. [source]

Fabrication and Electrochemical Properties of Epitaxial Samarium-Doped Ceria Films on SrTiO3 -Buffered MgO Substrates

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2009
Simone Sanna
Abstract Thin films of samarium-oxide-doped (20,mol%) ceria (SDC) are grown by pulsed-laser deposition (PLD) on (001) MgO single-crystal substrates. SrTiO3 (STO) prepared by PLD is used as a buffer layer on the MgO substrates to enable epitaxial growth of the fluorite-structured SDC film; the STO layer provides a proper crystalline match between SDC and MgO, resulting in highly crystalline, epitaxial SDC films grown in the (001) orientation. Film conductivity is evaluated by electrochemical impedance spectroscopy measurements, which are performed at various temperatures (400,775,°C) in a wide range of oxygen partial pressure (pO2) values (10,25,1,atm) in order to separate ionic and electronic conductivity contributions. At 700,°C, SDC/STO films on (100) MgO exhibit a dominant ionic conductivity of about 7,×,10,2,S cm,1, down to pO2 values of about 10,15,atm. The absence of grain boundaries make the SDC/STO/MgO heterostructures stable to oxidation-reduction cycles at high temperatures, in contrast to that observed for the more disordered SDC/STO films, which degraded after hydrogen exposure. [source]

Growth of magnetite epitaxial thin films by gas flow sputtering and characterization by FMR

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 4 2007
Hiroshi Sakuma Member
Abstract The growth of magnetite (Fe3O4) epitaxial thin films on MgO substrates were studied by using gas flow sputtering (GFS). Reflection high-energy electron diffraction (RHEED) and atomic force microscopy showed that the surfaces of the films obtained at a substrate temperature Ts of 300 °C and oxygen flow rates FO2 of 0.12 , 0.18 sccm are fairly flat for the film thickness of about 200 nm. The saturation magnetization and resistivity were close to the reported values of Fe3O4 for Ts= 300°C and FO2 = 0.12,0.20sccm. The films obtained at Ts= 300°C and FO2=0.16 and 0.18 sccm showed Verwey transition, which is persuasive evidence of the formation of Fe3O4. The epitaxial relationship of Fe3O4(100)//MgO(100) and Fe3O4[100]//MgO[100] was confirmed by using ferromagnetic resonance (FMR), and the anisotropy constants and magnetization were obtained by the fitting of resonance-field versus applied-field angle curves. © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]

Photoluminescence of cubic InN films on MgO (001) substrates

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008
T. Inoue
Abstract We have studied photoluminescence from cubic InN films grown on MgO substrates with a cubic GaN underlayer by RF N2 plasma molecular beam epitaxy. A single PL peak was observed at 0.47 eV. By analyzing the reflectance spectra of cubic InN films, we could derive the refractive index and extinction coefficient, and found the band gap energy of cubic InN is 0.48 eV, indicating that the PL peak observed at 0.47 eV is due to the interband transition of cubic InN. The difference in the PL peak energy between hexagonal and cubic InN is in good agreement with that predicted by ab-initio calculations. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Pinning energy of domain walls in MnZn ferrite films

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2007
V. H. Calle
Abstract Mn Zn ferrite films deposited on (100) MgO substrates by rf sputtering technique with different thicknesses , in the range of 30-450 nm were studied. AFM images show grain size increase as film thickness increases. Grains with diameters between L , 70 and 700 nm were observed. The mono and multidomain regime in MnZn ferrite films and their effect on the pinning energy of domain walls are observed via Magneto-optical Kerr Effect, MOKE. At , , 300 nm, the coercive field, Hc, reaches a maximum value of 80 Oe. This result indicates the existence of a multidomain regime associated to a critical grain size, Lc. We used the Jiles-Atherton model (JAM) to discuss the experimental hysteresis loops. The k pinning parameter obtained from JAM shows a maximum value of k /,o = 67 Am2 for grains with Lc , 529 nm. The total energy per unit area E was correlated with k and D. We found a simple phenomenological relationship given by E , kD; where D is the magnetic domain width. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Fabrication of 123-type high- Tc superconducting thin films on BaZrO3 -buffered MgO substrates

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2006
S. Adachi
Abstract We have developed a stable preparation process for high-quality thin films of YBa2Cu3Oy (123)-type high- Tc superconductors (HTS) for the ground plane of single-flux-quantum (SFQ) devices. The films were deposited on MgO (100) substrates by an off-axis DC magnetron sputtering method. During deposition, the substrates were directly heated by thermal radiation from a heater. No adhesive paste was used for fixing the substrate. Possibility of chip contamination due to the paste could be completely eliminated. The insertion of a BaZrO3(BZO)-buffer layer was effective to obtain flat epitaxial 123 films with complete c -axis orientation. The flat ground plane could play a role as a suitable foundation for multilayer films of SFQ devices. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]