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Annealing Time (annealing + time)
Selected AbstractsVoid formation in the Cu layer during thermal treatment of SiNx/Cu/Ta73Si27/SiO2/Si systemsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1-2 2005R. Hübner Abstract The thermal stability of a SiNx passivation layer and its influence on the annealing behavior of an amorphous Ta73Si27 diffusion barrier deposited between copper and SiO2 were analyzed by X-ray diffraction, glow discharge optical emission spectroscopy, Auger electron spectroscopy, scanning electron microscopy, and transmission electron microscopy. During heat treatment at a temperature Tan = 500 °C, diffusion of Cu atoms out of the Cu metallization into the SiNx passivation occurs. The Cu diffusion intensifies with increasing annealing temperature and annealing time and seems to be a necessary precondition for a defect formation process observed within the Cu metallization. Depending on the chemical composition of the SiNx/Cu interface, voids in the ,m-range can be formed within the Cu film. Compared to an unpassivated sample, heat treatment leads to a reduced diffusion of Ta atoms from the barrier through the copper into the SiNx/Cu interface. The barrier crystallization process into Ta5Si3 occurring during annealing at Tan = 600 °C is principally not affected by the presence of a SiNx passivation. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Abrupt Morphology Change upon Thermal Annealing in Poly(3-Hexylthiophene)/Soluble Fullerene Blend Films for Polymer Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Minjung Shin Abstract The in situ morphology change upon thermal annealing in bulk heterojunction blend films of regioregular poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM) is measured by a grazing incidence X-ray diffraction (GIXD) method using a synchrotron radiation source. The results show that the film morphology,including the size and population of P3HT crystallites,abruptly changes at 140,°C between 5 and 30,min and is then stable up to 120,min. This trend is almost in good agreement with the performance change of polymer solar cells fabricated under the same conditions. The certain morphology change after 5,min annealing at 140,°C is assigned to the on-going thermal transition of P3HT molecules in the presence of PCBM transition. Field-emission scanning electron microscopy measurements show that the crack-like surface of blend films becomes smaller after a very short annealing time, but does not change further with increasing annealing time. These findings indicate that the stability of P3HT:PCBM solar cells cannot be secured by short-time annealing owing to the unsettled morphology, even though the resulting efficiency is high. [source] Perfluorosulfonic acid,Tetraethoxysilane/polyacrylonitrile (PFSA-TEOS/PAN) hollow fiber composite membranes prepared for pervaporation dehydration of ethyl acetate,water solutionsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Hai-Kuan Yuan Abstract Preparation of organic-inorganic composite membranes and their pervaporation (PV) permeation and separation characteristics for the aqueous solution of ethyl acetate were described. Polyacrylonitrile (PAN) hollow fiber ultrafiltration membrane as support membrane, the mixtures of perfluorosulfonic acid (PFSA) and tetraethoxysilane (TEOS) by the sol-gel reaction as the coating solution, the PFSA-TEOS/PAN hollow fiber composite membranes by the different annealing conditions were prepared. The swelling of PFSA in ethyl acetate aqueous solutions was inhibited with addition of TEOS. The PFSA-TEOS/PAN composite membranes containing up to 30 wt % TEOS in coating solution exhibited high selectivity towards water, then the selectivity decreased and permeation flux increased with increasing the TEOS concentration more than 30 wt %. When the PFSA-TEOS/PAN composite membranes were annealed, the separation factor increased with increasing annealing temperature and time. Higher annealing temperature and longer annealing time promoted the crosslinking reaction between PFSA and TEOS in PFSA-TEOS/PAN composite membranes, leading to the enhanced selectivity towards water. For the PFSA/PAN and PFSA-TEOS/PAN composite membrane with 5 and 30 wt % TEOS annealed at 90°C for 12 h, their PV performance of aqueous solution 98 wt % ethyl acetate were as follows: the separation factors were 30.8, 254 and 496, while their permeation flux were 1430, 513 and 205 g/m2 h at 40°C, respectively. In addition, the PV performance of PFSA-TEOS/PAN composite membranes was investigated at different feed solution temperature and concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Positron Lifetime Study of the Crystal Evolution and Defect Formation Processes in a Scintillating GlassJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2009Jiaxiang Nie The crystal evolution and defect formation in scintillating glasses as a consequence of thermal annealing were studied by annihilation lifetime spectroscopy and UV-Vis absorption spectroscopy. The annihilation lifetime spectra and UV-Vis spectra were recorded on glass 50SiO2,45ZnO,5BaF2 before and after annealing at 580°C for 16, 32, and 48 h, respectively. The results show that the three lifetime components (,1, ,2, and ,3) and the corresponding intensities (I1, I2, and I3) change systematically with increasing annealing time. This reflects the crystal evolution and defect formation in the glass matrix. The continued crystal evolution was also revealed by the UV-Vis spectra, as the absorption edge of the material shifted to a lower energy with prolonged annealing. [source] Phase Separation Inducing Controlled Crystallization of GeSe2,Ga2Se3,CsI Glasses for Fabricating Infrared Transmitting Glass,CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2009Cunming Liu Infrared transmitting glass,ceramics based on the selected glass of 65GeSe2,25Ga2Se3,10CsI were obtained by a two-stage heat-treatment method. Results of X-ray diffraction and scanning electronic microscopy indicated that droplet-like nanoparticles containing cubic Ga2,,Ge,Se3 crystals are homogeneously generated in the glass,ceramics and that the whole glass,ceramic process is composed of phase separation, nucleation, and crystal growth. Evolutions of the optical and mechanical properties of glass,ceramics versus annealing time at the first-stage heat treatment were also investigated. Compared with the parent glass, the fabricated glass,ceramics show considerably enhanced fracture toughness, practicable infrared transparence, and microhardness, which confer them with considerable competitive advantages over currently used infrared materials. [source] Texturing Behaviors and Kinetics of NaCo2O4,, Thermoelectric MaterialsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2007P. H. Tsai Polycrystalline NaCo2O4,, materials were prepared using the solid-state reaction technique. The processing dependence of texturing evolution of NaCo2O4,, was investigated quantitatively. The results indicate that the extent of texture increased with increasing process duration and then reached the maximum when the materials were sintered at 900°C for 12 h. The texturing kinetics obeys an exponential relationship, suggesting that the texturing processing is dominated by self-diffusion mechanism. However, the texture extent decreased when the annealing time exceeded 12 h. The experimental results may provide new insights into the optimization of processing parameters for the fabrication of polycrystalline NaCo2O4,, materials with the desired microstructure. [source] Microstructure Development in Unsupported Thin FilmsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2002Brian P. Gorman To better understand the role of the substrate in the microstructural evolution of thin films, unsupported nanocrystalline yttrium-stabilized zirconia (ZrO2:16%Y or YSZ) films were examined as a function of temperature and annealing time. Grain growth, texturing, and pinhole formation were measured using transmission electron microscopy (TEM) and electron diffraction. Films were produced and subsequently annealed on metallic grids using a previously developed technique that results in near full density films at low annealing temperatures. Microstructural evolution in these films was unique compared with constrained films. Grains were found to spheroidize much more readily, ultimately resulting in the formation of porosity and pinholes. Grain growth was found to stagnate at a size particular to each annealing temperature, presumably due to the effects of Zener pinning. It is proposed that the lack of substrate strain and confinement effects allows for the dominance of surface energetics with respect to microstructural evolution. [source] Formation of Two Kinds of Hexagonally Arranged Structures in ABC Triblock Copolymer Thin Films Induced by a Strongly Selective Solvent VaporMACROMOLECULAR RAPID COMMUNICATIONS, Issue 22 2009Chunxia Luo Abstract An order,order transition (OOT) in the sequence of a hexagonally arranged core,shell cylinder to a double-hexagonally arranged dot in polystyrene- block -poly(butadiene)- block -poly(2-vinylpyridine) (SBV) triblock copolymer thin films is reported to be induced upon exposure to a solvent vapor that is strongly selective for the two end blocks. These two kinds of hexagonally arranged structures could form when the film thickness is 44, 123, and 223,nm. When the film thickness is decreased to 13,nm, the ordered structure is absent. The sizes of the core,shell cylinder structures formed with the same annealing time in films of different thickness are compared to address the effects of film thickness on the phase structure. The mechanism is analyzed from the total surface area of the blocks and the effective interaction parameter in the solvent vapor. [source] Analysis of traps in CVD diamond films through thermal depumping of nuclear detectorsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2004A. Balducci Abstract Carrier free paths in Chemical Vapour Deposition (CVD) diamond films depend on the presence of traps, which therefore strongly affect the performance of those CVD diamond based devices which rely on the electronic properties of the material, like radiation detectors. For the same reason, these devices can in turn be used as tools to study carrier dynamics. It is well known that some traps may be saturated by pre-irradiation with ionizing radiation (e.g. ,-particles), a process called "pumping" or "priming". Not all traps behave in the same way. Due to the large bandgap of diamond, both shallow (not affected by pumping) and deep traps for electrons and holes may exist. We measured, using 5.5 MeV 241Am ,-particles, the response of high quality CVD diamond based detectors after successive annealing steps performed at selected temperatures. The analisys of the decay of the detector efficency with annealing time at several temperatures allows a quantitative evaluation of the activation energy of these defects. Two main trapping centres connected to the pumping process were found, both related to holes, having activation energies of about 1.6 eV and 1.3 eV respectively. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Impurity free vacancy disordering of self-assembled InGaAs quantum dots by using PECVD-grown SiO2 and SiNx capping filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2003J. H. Lee Abstract Impurity free vacancy disordering (IFVD) of InGaAs self-assembled quantum dots (SAQDs) grown by metal organic chemical vapor deposition (MOCVD) method has been carried out at 700,°C for the time range from 1 min to 4 min by using SiO2 and SiNx,SiO2 dielectric capping layers. The photoluminescence (PL) peak was blue shifted up to 157 meV and its full width at half maximum (FWHM) was narrowed from 76 meV to 47 meV as the annealing time increased. The integrated PL intensity was increased after the thermal annealing, which may be attributed to a defect quenching. There was an optimum annealing condition to get the largest integrated PL intensity for each dielectric capping. SiNx,SiO2 double capping layers have been found to induce larger integrated PL intensity and better carrier confinement after the thermal annealing of SAQDs compared to SiO2 single capping layer, even though SiNx,SiO2 double capping induced larger blue-shift than SiO2 single capping. [source] Depth profile of thermal donors in NTDCZSiPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2003Y. X. Li Abstract The depth profile of thermal donors (TDs) produced by annealing neutron transmutation-doped Czochralski silicon (NTDCZSi) at high temperatures above 1000 °C first and then at 450,°C has been studied by means of the thermal conversion spreading resistance (TCSR). The concentration of the TDs increases with the distance from the surface of the sample, and its depth profile can be described by the error function when the annealing temperature is low or the annealing time is short. A peak is formed in the depth profile under the annealing condition of 1100,°C for 4 h. Combining with an infrared absorption study, it is found that the curves of the diffusivity coincide with the loss of interstitial oxygen. These results indicate that the distribution of the TDs depends on both the out-diffusion and the precipitation of oxygen. Neutron irradiation accelerates the out-diffusion of the oxygen in the surface region of the silicon and the oxygen precipitation in the bulk. [source] Crystallization and melting behavior of zenite thermotropic liquid crystalline polymers,POLYMER ENGINEERING & SCIENCE, Issue 2 2002K. P. Pramoda The crystallization and melting behavior of a DuPont ZeniteTM series, namely, Z 6000 and Z 8000B, thermotropic liquid crystalline polymer (TLCP) have been investigated by differential scanning calorimetry (DSC). Both, non-isothermal and isothermal crystallizations were carried out. From the non-isothermal experiments, the crystallization temperature was found to be 234°C for a cooling rate of 10°C/min whereas it was only 228°C for 40°C/min for Z 8000B, and was found to be 296°C and 290°C, respectively, for Z 6000. In the isothermal experiment both the thermal and crystallization behaviors were studied as a function of the annealing temperature and annealing time. Two types of transition processes were evidence in the low temperature region of the isothermal crystallization. One is fast transition, which may be regarded as liquid crystal transition, and is characterized by the enthalpy, which is independent of annealing time. The other is slow process, related to crystal perfection, and it shows increases in the transition temperature and enthalpy, which is dependent on annealing time. [source] Surface properties of hydrosilylated polyolefins annealed in supercritical carbon dioxidePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 4 2008S.-H. Zhu Abstract Two hydrosilylated polyolefin compounds are obtained by reacting polypropylene (PP) and polyethylene (PE) with di- and multi-functional hydride-terminated poly(dimethylsiloxane) (dH-PDMS and mH-PDMS), respectively. The PDMS-rich surface layers on these two samples show different Si concentrations but similar thicknesses. Samples of these materials are annealed in supercritical carbon dioxide (scCO2) at various temperatures and pressures for different periods of time. On the PP/dH-PDMS sample, an increase in the annealing temperature does not affect the Si concentration up to 120°C. However, the Si concentration is sharply reduced at T,=,150°C at which point the surface appears to be covered by SiO2 particles. Annealing the PP/dH-PDMS sample for short times leads to submicron scale SiO2 particle formation on the surface. The particles form aggregated clusters that spread all over the surface uniformly when the annealing time is extended. However, Si concentration on the PE/mH-PDMS sample surface is enhanced as the annealing temperature increases, reaching a maximum at an annealing temperature of 100°C. No particle formation is observed on the PE/mH-PDMS sample surface. The contact angle of both samples is found to increase with annealing temperature. Increasing the scCO2 pressure leads to a higher Si concentration on the surfaces of both samples. On the other hand, increasing the CO2 pressure leads to opposite trends in contact angle with the PP/dH-PDMS sample exhibiting an increasing contact angle and the PE/mH-PDMS sample exhibiting a decreasing one. Copyright © 2007 John Wiley & Sons, Ltd. [source] Syntheses of esters through poly(styrene sulfonic acid)/poly(vinyl alcohol) membrane reactorASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010Tadashi Uragami Abstract Cation exchange membranes prepared from poly(styrene sulfonic acid) (PSA) and poly(vinyl alcohol) (PVA) were cross-linked by both glyoxal and gultaraledehyde and cross-linked membranes furthermore were annealed. The ion exchange capacity of the resulting PSA/PVA membranes increased, and the water content and degree of swelling of PSA/PVA membrane decreased with increasing annealing time. The syntheses of esters from alcohol and acetic acid through various PSA/PVA membranes have been carried out in a diaphragm type cell consisting of two detachable parts in which the membrane was set in the middle of the two parts of cell. When an aqueous solution of alcohol and acetic acid on one part of cell and p -chloro benzene (Cl-Bz) on another part were set, esters formed by the catalytic action of PSA/PVA membrane increased on the Cl-Bz phase with time. These results support that the PSA/PVA membrane could perform both the reaction and separation. The formation of esters in this membrane reactor was a secondary reaction as well as general the esterification between alcohols and acids. The catalytic action in the esterification of the PSA/PVA membranes prepared by changing the ratio of PSA/PVA and the amount of casting solution was also investigated. The rate of esterification reaction was significantly dependent on the number of sulfonic acid group in the effective membrane volume. The rate of reaction per mEq SO3H increased with an increase of the degree of swelling of the membrane and decreasing membrane thickness. In the esterifications of methanol, ethanol and n -propanol with acetic acid, the reactivity through the PSA/PVA membrane was higher than that with HCl as catalyst. In that of n -butanol with acetic acid, however, it was vice versa. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Roll-Bonded Titanium/Stainless-Steel Couples, Part 1: Diffusion and Interface-Layer InvestigationsADVANCED ENGINEERING MATERIALS, Issue 1-2 2009S. Dziallach A survey of the diffusion of the alloying elements Fe, Ni and Cr in a roll-bonded titanium/stainless-steel couple after an application-orientated heat treatment is presented. Diffusion profiles of the investigated elements by means of EPMA, and the diffusion coefficients and activation energies for application-oriented short annealing times up to 12,min in a temperature range of 750 to 950,°C are determined. The transformation of the hcp , -titanium into bcc , -titanium has a significant influence on the diffusion of the elements. The forming interface layers are characterised by LOM and SEM pictures. [source] Modified Phase Diagram for the Barium Oxide,Titanium Dioxide System for the Ferroelectric Barium TitanateJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2007Soonil Lee The ferroelectric phase transition behavior in BaTiO3 was investigated for various annealing times, temperatures, and Ba/Ti ratios by means of a differential scanning calorimeter. Coupling these observations with powder X-ray diffraction and transmission electron microscopy allowed new insights into the barium oxide (BaO),titanium dioxide (TiO2) phase diagram. The transition temperature was varied systematically with the Ba/Ti ratio at annealing temperatures from 1200° to 1400°C in air. The transition temperature decreased with increasing concentrations of BaO and TiO2 partial Schottky defects, and showed a discontinuous change at the phase boundaries. Beyond the solubility region, two peritectoid reactions were confirmed and revised; first around 1150°C for Ba1.054Ti0.946O2.946,Ba2TiO4+BaTiO3 and second 1250°C for BaTi2O5,Ba6Ti17O40+BaTiO3, respectively. All other regimes of the BaO,TiO2 were found to be consistent with the reported diagrams in the literature. [source] Structure-to-Properties Relationship of Aliphatic Hyperbranched PolyestersMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 13 2007Abstract We investigated the effects of annealing on the rearrangement of the H-bond network microstructure and its influence on the thermal and rheological properties of the second pseudo-generation hyperbranched (HB) polyester based on 2,2-bis(methylol)propionic acid (Boltorn H20) in comparison to the fourth pseudo-generation HB polyester (Boltorn H40). During annealing the hydroxyl groups of HB polyesters form H-bonds with other hydroxyl or carbonyl groups. The formation of OH,OH H-bonds is favored at shorter annealing times, higher annealing temperatures, and for low pseudo-generation HB polyester, which has a low average molar mass, degree of branching, and core functionality. At temperatures up to 80,°C, Boltorn H20 indicates faster and more extensive H-bond formation as compared to Boltorn H40. This is reflected in its larger cleavage enthalpies and higher elastic contribution to the viscoelastic response. At 90,°C and above, the process of H-bond formation is delayed. Therefore, Boltorn H20 exhibits only viscous behavior in rheological measurements, and in DSC curves it shows strong exothermic transitions while heating the sample. [source] Effects of correlated disorder on the magneto-transport in colossal magnetoresistance manganitesPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 4 2009M. Egilmez Abstract Monte-Carlo simulations predict that a local correlated disorder is responsible for many of the novel transport and magnetic properties of colossal magnetoresistance (CMR) materials such as manganites. One important prediction of these models is that the resistivity at the metal,insulator transition (MIT) in manganites depends strongly on the correlated quenched disorder. However, experimental confirmation has been challenging since it is difficult to control the amount of disorder in these compounds. We carried out experiments on Sm0.55Sr0.45MnO3, a prototypical CMR manganite with a sharp MIT, whereby the oxygen-related disorder is systematically enhanced by low temperature thermal activation. We observe dramatic changes in the temperature dependence of resistivity at the MIT as the amount of quenched disorder is increased, occurring in a manner that is in agreement with theoretical predictions. Temperature dependence of resistivity of Sm0.55Sr0.45MnO3 for different annealing times at 350 °C in vacuum. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nanodomain growth in amorphous Si,C,NPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 2-3 2009W. Gruber Abstract Polymer-derived amorphous Si,C,N ceramics are phase separated into amorphous nanodomains after thermolysis. These nanodomains are expected to have a crucial importance for the extraordinary high temperature stability of these materials. We investigated nanodomain growth during isothermal annealing at 1400 °C using small angle X-ray scattering. The as-thermolyzed sample shows a domain radius of about 5 Å as determined from Guinier plots. During annealing, fast nanodomain growth up to 9 Å is observed for times up to 30 h while for longer annealing times up to 165 h the growth considerably slows down, resulting in a domain size of 11 Å. The experimental data can be fitted by a model based on diffusion controlled domain growth and simultaneous slow-down of diffusion due to structural relaxation. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||||||||||||||