Materials Literature
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High vacuum electron-beam co-evaporation, followed by N2 annealing at 500 °C is used for preparing of silicon nanocrystals (Si NCs) embedded in Al2O3 dielectric matrix. X-ray diffraction and transmission electron microscopy are used to investigate the structures of Si+Al2O3 films and estimate the mean diameter of the…
The magnetic, electric, and thermal transport properties of the single-crystal ${\mathrm{Pr}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ perovskites have been investigated in the compositional region $0.48<~x<~0.57.$ The end compositions are characterized as ideal examples of the ferromagnetic ${(T}_…
A characterization of the electrical and thermal properties of thermoelectric diode structures indicates that the figure of merit for thermal to electrical energy conversion is significantly enhanced in our devices over thermoelectric values. Enhancements are due to current injection and blockage of the ohmic return c…
The behavior of the bulk electrical resistivity of donor-doped BaTiO3 with the increase of donor concentration was investigated. A series of coarse-grained specimens with different donor concentrations were prepared by adjusting the oxygen partial pressure during sintering. Then they were heat treated in air for an ex…
The nature of oxide-supported metal catalysts may change in oxidizing conditions: Studies on the correlation between the Rh phase in the structure of the Rh/Al2O3 catalyst and the catalytic performance for the reduction of NO by H2 to N2 (on reduced, metallic sites) and N2O (on oxidized sites) reveal that the phases o…
The richness of spatial structures of the diblock copolymer melts is demonstrated by the minimization of a free-energy functional of nonlocal type. The total chain length and the interface thickness are key factors in determining the morphology of the system, in addition to the constant mean curvature surface ansatz.…
A new composite crystal cobaltite, [Ca 2 (Co 0.65 Cu 0.35 ) 2 O 4 ] 0.624 CoO 2 , has been synthesized and its thermoelectric properties below 300 K have been investigated. The compound consists of a CdI 2 -type CoO 2 conduction sheet and a quadruplicated rock-salt-type [Ca 2 (Co 0.65 Cu 0.35 ) 2 O 4 ] layer alternati…
We have studied luminescence spectrum and dynamics of Mn-doped CdS nanocrystals fabricated by sequential Cd+, S+, and Mn+ ion implantation into Al2O3 matrices. The photoluminescence (PL) due to the Mn2+ intra-3d transition is clearly observed near 570 nm in Mn-doped CdS nanocrystals. The PL excitation spectrum of the…
A system producing an optical pattern with a high spatial frequency at (lambda) equals 157 nm has been built to be used as a photoresist tool for the 157 nm lithography. In order to generate a test pattern with a high spatial frequency, two-beam interference was used to overcome the limits of existing mask-projection…
Lattice and magnetic properties are investigated for 3% Ru- and Cr-doped Nd 1/2 Ca 1/2 MnO 3 . The parent Nd 1/2 Ca 1/2 MnO 3 is a charge-ordered insulator ( T CO = 250 K). With decreasing temperature below ≈ 210 K, these compounds are separated into two perovskite phases, that is, the long- c and short- c phases. The…
We have studied electron-beam exposure of cobalt fluoride (CoF2) thin films by real-time high-resolution transmission electron microscopy and by electron energy-loss spectroscopy. We were able to remove fluorine completely from an irradiated area and retain metallic cobalt by exposing the area at low dose rate and ele…
The TiN(5 nm)/Al/TiN (5 nm) structure is fabricated by sequential sputtering for the diffusion barrier application against Cu diffusion. Al is used as an interlayer with an expectation that it will favor stuffing of TiN grain boundaries by reacting with O2 in the structure. In one phase of experiments, the upper TiN l…
Unterschiedlich katalytisch aktive Reaktionszentren auf getragenen Nanopartikeln konnten mithilfe von Molekülstrahltechniken und In-situ-Oberflächenschwingungsspektroskopie nachgewiesen werden. Am Beispiel der Methanolzersetzung an einem Pd-Modellträgerkatalysator (siehe Bild) wurde gezeigt, dass die konkurrierenden R…
(001)-Textured Cu2S Thin Films Deposited by RF Reactive Sputtering, He, Yunbin, Kriegseis, Wilhelm, Bläsing, Jürgen, Polity, Angelika, Krämer, Thorsten, Hasselkamp, Dietmar, Meyer, Bruno K., Hardt, Martin, Krost, Alois
The electronic and magnetic properties of the ferromagnetic half-metal CrO2 have been studied by using the full-potential linear muffin-tin orbital method within the local-spin-density approximation (LSDA) and the LSDA+U approach. The orbital magnetic moments are investigated by including the spin-orbit coupling in bo…
The nitronyl nitroxide 2-cyano-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (1) crystallises in the tetragonal P42(1)m space group with a=7.4050(7), c=8.649(1) A. In the crystal the molecules form layers parallel to the ab plane in which they are orthogonal to each other. In the layers there are close contacts, 2.953…
Density-functional calculations are used to study the electronic structure and transport properties of the type-I clathrates, K8Sn46, and K8Sn44□2, (□ is a missing Sn atom), and the type-III clathrate K8Sn25. We show K8Sn44□2 to be more stable than the defect-free K8Sn46, with K8Sn46 being metallic and K8Sn44□2; semim…
This paper reports the synthesis and characterization of a new class of diblock copolymers (co-oligomers), rod-rod conjugated diblock copolymers. A general synthetic strategy is outlined, and the structures of the copolymers (oligothiophene-co-oligophenylenevinylene) are fully characterized. It was found that these co…
An experimental phase diagram of the field-induced superconductivity in the lambda-(BETS)_2FeCl_4 compound is theoretically reproduced by a combination of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state and the Jaccarino-Peter mechanism. Semi-quantitative agreement is obtained in the presence of a very weak subdomin…
The thermoelectric properties of solid solutions of the type β-K2Bi8−xSbxSe13 (0&lt;x&lt;8) were studied with respect to thermal behavior, band gap variation, and charge transport properties as a function of x. At x values between 0 and 1.5, the energy band gap is observed to decrease (anomalous) before it wid…