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Annealing Step (annealing + step)
Selected AbstractsHigh K Capacitors and OFET Gate Dielectrics from Self-Assembled BaTiO3 and (Ba,Sr)TiO3 Nanocrystals in the Superparaelectric LimitADVANCED FUNCTIONAL MATERIALS, Issue 4 2010Limin Huang Abstract Nanodielectrics is an emerging field with applications in capacitors, gate dielectrics, energy storage, alternatives to Li-ion batteries, and frequency modulation in communications devices. Self-assembly of high k dielectric nanoparticles is a highly attractive means to produce nanostructured films with improved performance,namely dielectric tunability, low leakage, and low loss,as a function of size, composition, and structure. One of the major challenges is conversion of the nanoparticle building block into a reliable thin film device at conditions consistent with integrated device manufacturing or plastic electronics. Here, the development of BaTiO3 and (Ba,Sr)TiO3 superparaelectric uniform nanocrystal (8,12,nm) films prepared at room temperature by evaporative driven assembly with no annealing step is reported. Thin film inorganic and polymer composite capacitors show dielectric constants in the tunable range of 10,30, dependent on composition, and are confirmed to be superparaelectric. Organic thin film transistor (TFT) devices on flexible substrates demonstrate the readiness of nanoparticle-assembled films as gate dielectrics in device fabrication. [source] Effects of annealing lyophilized and spray-lyophilized formulations of recombinant human interferon-,JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2003Serena D. Webb Abstract The purpose of this study was to examine the effects of adsorption of recombinant human interferon-, (rhIFN-,) on ice surfaces and subsequent drying during processing by spray-lyophilization and lyophilization. Ice/liquid interfacial areas were manipulated by the freezing method as well as by the addition of an annealing step during lyophilization; that is, rhIFN-, adsorption was modified by the addition of nonionic surfactants. rhIFN-, was lyophilized or spray-lyophilized at a concentration of 1 mg/mL in 5% sucrose, 5% hydroxyethyl starch (HES),±,0.03% polysorbate 20 in 140 mM KCl, and 10 mM potassium phosphate, pH 7.5. After the samples were frozen, half were annealed on the lyophilizer shelf. Recovery of soluble protein was measured at intermediate points during processing. On drying, the secondary structure of rhIFN-, was determined by second-derivative infrared (IR) spectroscopy, specific surface areas (SSAs) were measured, scanning electron micrographs (SEM) were taken, and dissolution times were recorded. Adsorption of rhIFN-, to ice/liquid interfaces alone was not responsible for aggregation. Rather, drying was necessary to cause aggregation in lyophilized sucrose formulations. Addition of an annealing step to the lyophilization cycle resulted in more native-like secondary protein structure in the dried solid, eliminated cracking of the dried cakes, and suppressed both the formation of air/liquid interfaces and rhIFN-, aggregation on reconstitution. © 2003 Wiley-Liss, Inc. and the American pharmaceutical Association J Pharm Sci 92:715,729, 2003 [source] Freeze-drying using vacuum-induced surface freezingJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2002Martin Kramer Abstract A method of freezing during freeze-drying, which avoids undercooling of a solution and allows growth of large, dendritic ice crystals, was investigated. Aqueous solutions of mannitol, sucrose, or glycine were placed under a chamber vacuum of approximately 1 mbar at a shelf temperature of,+,10°C. Under these conditions, the solutions exhibit surface freezing to form an ice layer of approximately 1,3 mm thickness. On releasing the vacuum and lowering the shelf temperature to below the freezing point of the ice in the solution, crystal growth occurs to yield large, chimney-like ice crystals. The duration of primary drying of a frozen cake,as measured by using inverse comparative pressure measurement,was up to 20% shorter than when using a "moderate" freezing procedure (2 K shelf temperature per min). With mannitol, however, the residual moisture content of the final dried product was higher than with moderate freezing, and with sucrose and glycine there was no difference. These findings are related to the structures of the dried cakes formed during freezing, as examined by light microscopy and wide-angle X-ray diffraction. The introduction of an annealing step (4 h at a shelf temperature slightly above the onset melting point of the ice in the frozen cake) combined with the vacuum-induced surface freezing procedure maintains the rapid primary drying and produces a low residual moisture (0.2%) for the freeze-dried mannitol solution. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:433,443, 2002 [source] Particle size effect on the film-forming process of PS/PBA composite latexesPOLYMER COMPOSITES, Issue 9 2010aziye U In this work, the effect of hard particle size and blend ratio on the film formation behavior of hard polystyrene (PS) and soft poly(n -butyl acrylate) (PBA) latex blends was studied by means of steady-state fluorescence and UV,visible techniques in conjunction with atomic force microscopy. Three different sets of latexes were synthesized: PBA latex (diameter 97 nm), pyrene (P)-labeled large PS (LgPS; diameter 900 nm), and small PS (SmPS; diameter 320 nm). Two different series of latex blends (LgPS/PBA and SmPS/PBA) were prepared with varying blend composition at room temperature separately. Films were then annealed at elevated temperatures above glass transition (Tg) temperature of PS. Fluorescence intensity (IP) from P and photon transmission intensity (Itr) were measured after each annealing step to monitor the stages of film formation. The results showed that a significant change occurred in IP and Itr at a certain critical weight fraction (Rc) of PBA. Below Rc, two distinct film formation stages, which are named as void closure and interdiffusion, were seen. However, at PBA concentrations nearer to or above Rc, no film formation can be achieved. Comparing to the LgPS/PBA, the sintering process of SmPS/PBA particles occurred at much lower temperatures. Film formation stages for R < Rc were modeled, and related activation energies were calculated. Void closure (,H) and interdiffusion (,E) activation energies for SmPS/PBA were also found smaller in comparing with LgPS/PBA series. However, ,H and ,E values were not changed much with the blend composition for both series. POLYM. COMPOS., 31:1637,1652, 2010. © 2009 Society of Plastics Engineers [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] Formation of endothermic carbides on iron and nickelPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2004A. Wiltner Abstract The formation of endothermic carbides on Fe and Ni is studied using X-ray photoelectron spectroscopy (XPS) by deposition of carbon films from the vapor phase and subsequent annealing steps. The reaction between carbon and metal substrates is measured by shifts in the C 1s photoelectron peaks. By comparison with two elementary carbon photoelectron energies determined from carbon films on unreactive Au substrates, a carbide peak in the C 1s spectra on reactive Fe and Ni substrates is identified. The carbides formed after deposition of carbon films at room temperature are located at the interface between carbon film and metal substrate. We report on the behavior of elementary carbon films with respect to film thickness and thermal treatment leading to carbide formation and carbon diffusion into the bulk. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nanowire,quantum-dot,polymer solar cellPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2008A. Nadarajah Abstract We report first results on a new solar cell structure which incorporates n-type ZnO nanowires, an undoped CdSe layer, obtained from quantum dot precursors, and a p-type polymer layer as the main components. In the fabrication process the quantum dot layer is converted to a conformal ,30 nm thick polycrystalline film. The fabrication of the cell occurs in lab air at temperatures below 100 °C. Several intermittent annealing steps raise the energy conversion efficiency to approximately 1%. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||