Materials Literature
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Material design to achieve a f high dielectric constant of ε 33 T / ε 0 >5,000 and a large planar-mode electromechanical coupling factor (EMCF) of k p >65% near the morphotropic phase boundary (MPB) in the multicomponent system of Pb(Sc 1/2 Nb 1/2 )O 3 -Pb(Mg 1/3 Nb 2/3 )O 3 -Pb(Ni 1/3 Nb 2/3 )O 3 -(Pb,Ba,Sr)(Zr…
A microscopic theory is developed for the interplay of diffusion and chemical reaction and the results are compared with electrode impedance measurements on an oxide electrode. The theory is based on the ideas of continuous-time random walk and accounts for the interference of diffusion and recombination of the charge…
Abstract— The synthesis of carbon‐nanotube (CNT) field emitters for FEDs by thermal chemical vapor deposition (CVD) and their structural and emission characterization are described. Multi‐walled nanotubes (MWNTs) were grown on patterned metal‐base electrodes by thermal CVD, and the grown CNTs formed a network structur…
Commercial coconut shell based activated carbon (AC) was used to investigate the production of increased mesoporosity by impregnating with catalytic metal salts such as Fe(NO_3)_3 and Fe_2(SO_4)_3 followed by CO_2 gasification. The salts are found be effective in enlarging the pore size of AC and Fe(NO_3)_3 is the mor…
In the last decade, progress in diamond growth by chemical vapor deposition (CVD) has resulted in significant improvement in the quality of synthetic single crystals. This article reports on the gemological and spectroscopic features of six synthetic type IIa diamonds grown for research purposes at the French Laborato…
Mechanical and electrical properties of specimens of ZrO 2 (3Y) doped with RENbO 4 (RE =Yb, Er, Y, Dy, YNd, Sm, Nd) were investigated using micro-indentation and impedance spectroscopy in this work. The results show that ZrO 2 (3Y) doped with RENbO 4 (RE=Yb, Er, Y, Dy) possess outstanding mechanical properties, and sp…
Ultrafine‐grained copper samples produced by equal channel angular pressing were cyclically deformed at different temperatures under a constant stress amplitude of 200 MPa, and the corresponding microstructures were investigated by transmission electron microscope. The increase in temperature during cycling facilitate…
A diffusion couple of 3 mol% Y2O3–ZrO2 and titanium was isothermally annealed in argon at temperatures between 1100° and 1550°C. The phases and microstructure in the ceramic side were investigated using scanning electron microscopy and transmission electron microscopy, both attached to an energy-dispersive spectromete…
The effect of adding a Li 2 SiO 3 (LSO) sintering aid for low temperature fabrication of BaTiO 3 (BT) thick films was investigated. LSO-added BT thick films were prepared by the screen printing method on Pt-coated ZrO 2 substrates. Their sintering properties were significantly improved by the addition of LSO, and the…
Nanopowders of yttrium aluminium garnet Y3Al5O12 (YAG) doped with neodymium ions were obtained by the co-precipitation method from the reaction of aluminium and yttrium nitrate and neodymium oxide with ammonia. After washing and drying the hydroxide precursors were calcined at 500, 700, 800 and 900 °C for 1 hour and a…
The CCA-adding enzymes [ATP(CTP):tRNA nucleotidyl transferases] catalyze synthesis of the conserved and essential CCA sequence to the tRNA 3' end. These enzymes are divided into two classes of distinct structures that differ in the overall orientation of the head to tail domains. However, the catalytic core of the two…
Abstract Polyaniline (PAni) films of different intrinsic oxidation states, including emeraldine salt, emeraldine base and leucoemeraldine base, were synthesized. Free‐standing membranes and thin film bilayers of aluminum–polyaniline were fabricated by magnetron sputter deposition of aluminum onto polyaniline films. Al…
Nanocomposite materials were prepared by incorporating multiwall carbon nanotubes (MWNTs), obtained by acetylene catalytic chemical vapor deposition (CCVD) on Co/Fe‐modified MgO, within poly(vinyl alcohol) (PVA). Before incorporation, nanotubes were oxidized to obtain better compatibilization with the polymer. It has…
Silver of 3N purity was deformed at room temperature by equal channel angular pressing (ECAP) using three passes of route A. The global and local texture were investigated by neutron diffraction and high-energy synchrotron radiation, respectively. The texture is characterized by typical simple shear components of fcc…
A calcium analog of strontioborite, namely, Ca[B 8 O 11 (OH) 4 ], is synthesized under hydrothermal conditions ( T = 270°C, P = 20 atm) within the framework of the study of the phase formation in the CaCl 2 · Rb 2 CO 3 · B 2 O 3 system. The crystal structure of the synthetic calcium borate [ a = 7.4480(5) Å, b = 8.262…
Binary diffusion-limited cluster-cluster aggregation processes are studied as a function of the relative concentration of the two species. Both, short and long time behaviors are investigated by means of three-dimensional off-lattice Brownian Dynamics simulations. At short aggregation times, the validity of the Hogg-H…
Ceramic samples of the series 1-x (Na 1/2 Bi 1/2 TiO 3 )–x (BiFeO 3 ) were made using a conventional solid state sintering technique. X-ray diffraction studies reveal their rhombohedral symmetry at room temperature. Temperature and frequency dependant dielectric measurements show that the transition temperature (Tc) s…
Dielectric properties of a novel liquid crystal with direct transition from isotropic to twist grain boundary (TGB) phase were studied. Measurements were performed over a wide range of temperature in the isotropic phase, TGBA, TGBC and SmC* phases. The Arrhenius plot of the relaxation frequency of the molecular proces…
We have developed a high-throughput x-ray characterization system, which can rapidly screen structure, composition and x-ray scintillation of combinatorial materials libraries using energy-dispersive x-ray diffraction, x-ray fluorescence, and x-ray photoluminescence. This system consists of an x-ray source, a polycapi…
By means of first-principles calculations we show that hydrogenated silicon nanowires in the ⟨001⟩ orientation can have a direct band gap with appreciable oscillator strength of the first direct transition if their surface is characterized by dimers displaying the SiH species. The breaking of some dimers (the SiH2 spe…