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Subsequent Annealing (subsequent + annealing)
Selected AbstractsChange in the magnetic properties of [FeII(phen)3](PF6)2 in the solid state by combining grinding and annealingPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2004T. Ohshita Abstract By grinding crystalline [FeII(phen)3](PF6)2, the effective magnetic moment, or ,MT, increased with simultaneous amorphization. Subsequent annealing further increased ,MT, despite the restoration of the crystallinity. This was explained by the recovery of the counterion, PF6,, from its strained state in the intact crystal to a less strained state towards higher spherical symmetry. The effects of annealing preceded by grinding suggest a novel method to control the magnetic states of coordination compounds without regard to their crystalline states. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Formation of 1,D and 3,D Coordination Polymers in the Solid State Induced by Mechanochemical and Annealing Treatments: Bis(3-cyano-pentane-2,4-dionato) Metal ComplexesCHEMISTRY - A EUROPEAN JOURNAL, Issue 34 2008Jun Yoshida Abstract Bis(3-cyano-pentane-2,4-dionato) (CNacac) metal complex, [M(CNacac)2], which acts as both a metal-ion-like and a ligand-like building unit, forms supramolecular structures by self-assembly. Co-grinding of the metal acetates of MnII, CoII, NiII, CuII and ZnII with CNacacH formed a CNacac complex in all cases: mononuclear complex was formed in the cases of MnII, CuII and ZnII, whereas polymeric ones were formed in the cases of FeII, CoII and NiII. Subsequent annealing converted the mononuclear complexes of MnII, CuII and ZnII to their corresponding polymers as a result of dehydration of the mononuclear complexes. The resultant MnII, FeII, CoII, NiII and ZnII polymeric complexes had a common 3,D structure with high thermal stability. In the case of CuII, a 1,D polymer was obtained. The MnII, CuII and ZnII polymeric complexes returned to their original mononuclear complexes on exposure to water vapour but they reverted to the polymeric complexes by re-annealing. Co-grinding of metal chlorides with CNacacH and annealing of the mononuclear CNacac complexes prepared from solution reactions were also examined for comparison. [Mn(CNacac)2(H2O)2], [M(CNacac)2(H2O)] (M=CuII and ZnII) and [M(CNacac)2], (M=MnII, FeII and ZnII) are new compounds, which clearly indicated the power of the combined mechanochemical/annealing method for the synthesis of varied metal coordination complexes. [source] Synthesis of the Clathrate-II K8.6(4)Ge136 by Oxidation of K4Ge9 in an Ionic LiquidEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 17 2009Arnold M. Guloy Abstract The new clathrate-II K8.6(4)Ge136 has been synthesized by mild oxidation of K4Ge9 in the ionic liquid n -dodecyltrimethylammonium chloride (DTAC)/AlCl3 at 300 °C and subsequent annealing at 370 °C. Refinement of the crystal structure from X-ray powder diffraction data revealed the composition K8.6(4)Ge136 [space group Fdm, a = 15.302(1) Å], which was also confirmed by energy-dispersive X-ray spectrometry (EDXS), transmission electron microscopy, and scanning electron microscopy on the bulk material. K atoms preferably occupy the larger Ge28 cages rather than the Ge20 cages in the clathrate-II structure. K8.6(4)Ge136 is metastable and was found to decompose exothermically at 471 °C. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Bottom-Up Engineering of Subnanometer Copper Diffusion Barriers Using NH2 -Derived Self-Assembled MonolayersADVANCED FUNCTIONAL MATERIALS, Issue 7 2010Arantxa Maestre Caro Abstract A 3-aminopropyltrimethoxysilane-derived self-assembled monolayer (NH2SAM) is investigated as a barrier against copper diffusion for application in back-end-of-line (BEOL) technology. The essential characteristics studied include thermal stability to BEOL processing, inhibition of copper diffusion, and adhesion to both the underlying SiO2 dielectric substrate and the Cu over-layer. Time-of-flight secondary ion mass spectrometry and X-ray spectroscopy (XPS) analysis reveal that the copper over-layer closes at 1,2-nm thickness, comparable with the 1.3-nm closure of state-of-the-art Ta/TaN Cu diffusion barriers. That the NH2SAM remains intact upon Cu deposition and subsequent annealing is unambiguously revealed by energy-filtered transmission electron microscopy supported by XPS. The SAM forms a well-defined carbon-rich interface with the Cu over-layer and electron energy loss spectroscopy shows no evidence of Cu penetration into the SAM. Interestingly, the adhesion of the Cu/NH2SAM/SiO2 system increases with annealing temperature up to 7.2,J m,2 at 400,°C, comparable to Ta/TaN (7.5,J m,2 at room temperature). The corresponding fracture analysis shows that when failure does occur it is located at the Cu/SAM interface. Overall, these results demonstrate that NH2SAM is a suitable candidate for subnanometer-scale diffusion barrier application in a selective coating for copper advanced interconnects. [source] Enhanced Thermal Stability and Efficiency of Polymer Bulk-Heterojunction Solar Cells by Low-Temperature Drying of the Active LayerADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Ching Lin Abstract This study addresses two key issues, stability and efficiency, of polymer solar cells based on blended poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) by demonstrating a film-forming process that involves low-temperature drying (,5,°C) and subsequent annealing of the active layer. The low-temperature process achieves 4.70% power conversion efficiency (PCE) and ,1250,h storage half-life at 65,°C, which are significant improvements over the 3.39% PCE and ,143,h half-life of the regular room-temperature process. The improvements are attributed to the enhanced nucleation of P3HT crystallites as well as the minimized separation of the P3HT and PCBM phases at the low drying temperature, which upon post-drying annealing results in a morphology consisting of small PCBM-rich domains interspersed within a densely interconnected P3HT crystal network. This morphology provides ample bulk-heterojunction area for charge generation while allowing for facile charge transport; moreover, the P3HT crystal network serves as an immobile frame at heating temperatures less than the melting point (Tm) of P3HT, thus preventing PCBM/P3HT phase separation and the corresponding device degradation. [source] Ion beam synthesis of buried Zn-VI quantum dots in SiO2, grazing incidence small-angle X-ray scattering studiesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2003I.D. Desnica-Frankovic Grazing incidence small-angle X-ray scattering was used to study ion-beam synthesized Zn-VI compound-semiconductor quantum dots (QDs), buried in a SiO2 matrix. The ZnTe and ZnS QDs were formed by successive ion implantation of constituent atoms, at high ion doses and subsequent annealing at different temperatures in the 1070,1370 K range. In Zn and Te implanted SiO2, small nano-crystals were formed at higher annealing-temperatures, a bimodal size distribution of nano-particles was observed for both materials, which could be explained by an interplay of Ostwald ripening and enhanced diffusion in the irradiation-damaged region. [source] Grazing incidence small-angle X-ray scattering studies of the synthesis and growth of CdS quantum dots from constituent atoms in SiO2 matrixJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2003U.V. Desnica Grazing incidence small angle X-ray scattering was applied to study the synthesis and growth of CdS quantum dots (QDs) from Cd and S atoms implanted in SiO2. For a dose of 1017/cm2, the partial synthesis of CdS QDs occurred already during implantation, with only moderate size increase upon subsequent annealing up to Ta=1073 K. The dynamics of QD synthesis and growth were considerably different for just two times lower dose, where synthesis started only if the implanted samples were annealed at Ta = 773 K or higher, with a strong increase of the size of QDs upon annealing at higher Ta. The results suggest that high-dose implantation followed by low-temperature annealing could lead to better defined sizes and narrower size distributions of QDs. [source] Vibrational spectroscopic studies, conformations and quantum chemical calculations of 3,3,3-trifluoropropyl- silane and 3,3,3-trifluoropropylsilane- d3,JOURNAL OF RAMAN SPECTROSCOPY, Issue 1-3 2006Peter Klaeboe Abstract Infrared spectra of 3,3,3-trifluoropropylsilane (CF3CH2CH2SiH3) and 3,3,3-trifluoropropylsilane- d3 (CF3 CH2CH2SiD3) were obtained in the vapour, liquid, and crystalline solid phases in the range 4000,50 cm,1. Additional spectra in argon matrices at 5 K were recorded before and after annealing to temperatures 20,34 K. Raman spectra of the compounds as liquids were recorded at various temperatures between 296 and 183 K and spectra of the amorphous and crystalline solids were obtained. The spectra revealed the existence of two conformers (anti and gauche) in the fluid phases and in the matrices. When the two vapours were shock-frozen on a cold finger at 78 K, they turned partly crystalline immediately. After subsequent annealing to 140,150 K, ca 7,9 Raman bands of both molecules present in the liquids vanished in the crystal. Similar variations in intensity were observed in the corresponding infrared spectra before and after annealing. The spectra revealed the existence of one conformer (anti) in the crystal. From Raman intensity variations of three independent pairs of anti and gauche bands between 298 and 173 K for the parent compound, and 298 and 183 K for the deuterated analogue, the values ,confHo(gauche,anti) = 4.1 ± 0.3 kJ mol,1 for the parent compound and the same value for the deuterated species were obtained in the liquid state. Annealing experiments in the matrices show that the gauche bands vanish after annealing, demonstrating that the anti conformer also has the lower energy here and that the barrier to gauche , anti inter-conversion is around 5,6 kJ mol,1. The spectra of both conformers have been interpreted in detail. Ab initio and DFT calculations at the HF/6,311G**, B3LYP/6,311 G** and MP2/6,311 G** levels gave optimized geometries, infrared and Raman intensities and vibrational wavenumbers for the anti and gauche conformers. The conformational enthalpy difference derived from the calculations was between 6.0 and 4.1 kJ mol,1 with anti being the low energy conformer. Copyright © 2006 John Wiley & Sons, Ltd. [source] XAFS study on gallium ions implanted in silicon carbideJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2001Hirotaka Yamaguchi Local structure of gallium ions implanted in silicon carbide has been investigated using extended X-ray absorption fine structure on the Ga K-edge. The crystallinity of the implantation layer is compared in the samples prepared under several different conditions of implantation temperature and post-implantation annealing. It is found that significant damage is induced by the implantation at room temperature, but the crystallinity recovers by the subsequent annealing at high temperature at 1600 °C. On the other hand, the best crystallinity is obtained by the implantation at high temperature of 500 °C, but the annealing results in degrading the crystallinity. This indicates an influence of the post-implantation annealing at high temperature on the crystallinity in atomic level, which relates to the secondary defects in lattice observed by electron microscope. [source] Relationship between Microstructure and Fracture Toughness of Toughened Silicon Carbide CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2001Sung-Gu Lee Different microstructures in SiC ceramics containing Al2O3, Y2O3, and CaO as sintering additives were prepared by hot-pressing and subsequent annealing. The microstructures obtained were analyzed by image analysis. Crack deflection was frequently observed as the toughening mechanism in samples having elongated ,-SiC grains with aspect ratio >4, length >2 ,m, and grain thickness (t) <3 ,m (defined as key grains 1). Crack bridging was the dominant toughening mechanism observed in samples having grains with thickness of 1 ,m < t < 3 ,m and length >2 ,m (key grains 2). The values of fracture toughness varied from 5.4 to 8.7 MPa·m1/2 with respect to microstructural characteristics, characterized by mean grain thickness, mean aspect ratio, and total volume fraction of key grains. The difference in fracture toughness was mainly attributed to the amount of key grains participating in the toughening processes. [source] Passivation study of the amorphous,crystalline silicon interface formed using DC saddle-field glow dischargePHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2010Barzin Bahardoust Abstract The DC saddle-field (DCSF) glow discharge method was used to deposit intrinsic a-Si:H onto c-Si to passivate the c-Si surface. The effective minority carrier lifetime in the heterostructures as a function of the excess minority carrier density in the c-Si wafers was measured. The results were then analyzed in the context of recombination associated with interface defect states using three known recombination models. The defect density and the charge density at the interface are inferred. In addition subsequent annealing of the samples was studied. It is shown that for our intrinsic a-Si:H samples improvements in surface passivation are directly correlated with the reduction of interface defects and not the reduction of minority carrier concentration at the interface due to electric field. We have achieved excellent surface passivation with effective carrier lifetime >4,ms for an intrinsic a-Si:H sample deposited at a process temperature of 200,°C and thickness of about 30,nm. It is also demonstrated that subsequent annealing, at 240,°C, of the samples which were prepared at process temperatures <240,°C greatly increases the effective lifetime. [source] Top-down processed silicon nanowire transistor arrays for biosensingPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2009Xuan Thang Vu Abstract We describe the fabrication, electrical and electrochemical characterization of silicon nanowire arrays, which were processed in a top-down approach using combined nanoimprint lithography and wet chemical etching. We used the top silicon layer as contact line and observed an influence of implantation and subsequent annealing of these lines to the device performance. In addition we found a subthreshold slope dependence on wire size. When operated in a liquid environment, wires can be utilized as pH sensors. We characterized the pH sensitivity in the linear range and in the subthreshold operation regime. As a first proof-of-principle experiment for the later use of the sensors in bioassays, we monitored the buildup of polyelectrolyte multilayers on the wire surface. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Schottky contacts to hydrogen doped ZnOPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2008R. Schifano Abstract High resistivity (,1 k, cm) hydrothermally grown single crystal ZnO wafers were modified by hydrogen implantation. The implantation has been performed with multiple energies in order to form a box-like profile with a depth of 4 ,m and two different concentrations of 8 × 1017 H/cm3 and 1.5 × 1018 H/ cm3. A subsequent annealing at 200 °C for 30 min in N2 resulted in the formation of a highly conductive layer. Pd con- tacts deposited on the implanted side showed rectifying behaviour by up to three orders of magnitude. However by capacitance vs. voltage (C ,V) technique a carrier concentration significantly lower than the one expected according to the implanted H content was measured suggesting the presence of a high density of compensating centers and/or an incomplete activation of H as a donor. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Fabrication and properties of InSb films with ion-beam sputtering for use in the amplification of magneto-surface-acoustic wavesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2004N. Obata Abstract The magnetic surface acoustic wave (MSAW) device can be manipulated by an external magnetic field. However the MSAW is attenuated largely at high frequencies above MHz. Therefore, we proposed a MSAW device having a hybrid structure consisting of FeB amorphous thin film/InSb semiconductor thin film/LiNbO3 substrate. This device is utilized for amplification of surface acoustic waves by the interaction between surface acoustic waves and the carriers in the InSb semiconductor. We prepared (111) InSb thin films by ion beam sputtering. We obtained InSb thin films having Hall mobilities of about 2000 cm2/Vs by subsequent annealing. This showed the possibility of MSAW amplification by low voltages. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The electronic and electrochemical properties of the LaNi5 -based alloysPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003A. Szajek Abstract Nanocrystalline La(Ni,M)5 -type alloys were prepared by mechanical alloying (MA) and subsequent annealing. The alloying elements of 3d transition metals, Mn, Al and Co were substituted for Ni in LaNi5, and the structural, electrochemical as well as electronic properties were studied. It was found that the partial substitution of Ni by Al or Mn in nanocrystalline La(Ni,M)5 alloy leads to an increase in the discharge capacity. On the other hand, cobalt substituting nickel in LaNi4,xMn0.75Al0.25Cox alloy greatly improved the discharge capacity and cycle life of LaNi5 material. The electronic structure has been studied by the tight binding version of the linear muffin-tin orbital method (TB LMTO) for La(Ni0.8,xCoxAl0.1Mn0.1)5 systems, where x = 0, 0.1, 0.2, and 0.3. [source] Optimisation of surface passivation for highly reliable angular AMR sensorsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2010M. Isler Abstract For state-of-the-art angular sensors based on the anisotropic magnetoresistive (AMR) effect in NiFe layers, the angular accuracy over time is limited by a drift of the offset voltage of the Wheatstone bridge configuration. It is shown that the interaction of the passivation layer and the magnetic permalloy is crucial for the drift of the offset voltage. By investigating the time and temperature dependence, the offset drift is attributed to stress relief of the PECVD passivation layer due to microstructural changes. Hydrogen outdiffusion from the passivation layer is involved in the observed stress evolution. It is demonstrated that optimising the passivation layer composition as well as the time of the subsequent annealing is beneficial for stress stabilisation of the permalloy-passivation layer system. With this optimised passivation layer a significant offset drift reduction of the NiFe Wheatstone bridge has been achieved resulting in highly accurate and long-term stable angular AMR sensors. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Oxidation-induced high-Curie-temperature ferromagnetism in CoAl(100)PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2007V. Rose Abstract In conventional magnetic materials, oxidation is a disagreeable effect that often lowers or destroys the magnetic capabilities of those materials. By contrast, we report on the decisive paramagnetic-ferromagnetic phase transition in CoAl(100) at room temperature, utilizing oxidation of stoichiometric CoAl. We also discuss the control and drastic increase of the coercive field by subsequent annealing of the oxidized sample. The alumina film grown by selective oxidation protects the alloy from oxidation of Co, despite the accumulation of Al vacancies and the resulting enrichment in Co of the metallic phase underneath the oxide film. As a result, a ferromagnetic thin Co-rich phase is formed at the interface between the insulating aluminum oxide and the paramagnetic Co50Al50 bulk. The creation via simple oxidation of a ferromagnetic thin film underneath a surface insulator demonstrates a novel path to building the majority of a magnetic tunnel junction. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||||||||