Materials Literature
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The coefficient of diffusion of hydrogen in crystalline silicon is calculated using tight-binding molecular dynamics. Our results are in good quantitative agreement with an earlier study by Panzarini and Colombo [Phys. Rev. Lett. 73, 1636 (1994)]. However, while our calculations indicate that long jumps dominate over…
High-energy (>1.6 MeV) electrons create acceptors and donors in single-crystal ZnO. Greater damage is observed for irradiation in the [0001] direction (Zn face) than in the [0001̄] direction (O face). The major annealing stage occurs at about 300–325 °C, and is much sharper for defects produced by Zn-face irrad…
We report on the investigation of ferroelectricity in thin tetragonal single-crystalline perovskite films of Pb(Zr0.2Ti0.8)O3 grown by off-axis rf magnetron sputtering. The local ferroelectric properties of atomically smooth films, with thicknesses ranging from a few unit cells to 800 Å, were measured using a combinat…
We observe that field emitters made from carbon nanotubes exhibit excellent macroscopic emission properties; they can operate at a very large current density, as high as 4 A/cm2. At electric fields as low as 4–7 V/μm, they emit technologically useful current densities of 10 mA/cm2. We show that the emission originates…
By differential scanning calorimetry (DSC), the thermal behavior of polytetrafluoroethylene (PTFE) and random fluorinated copolymers of tetrafluoroethylene-containing hexafluoropropylene (FEP copolymers) or perfluoroalkylvinylether (PFA copolymers) as comonomers was investigated. Rapid-melt crystallization was employe…
Soluble polyimides were synthesized and characterized from two diamines and four dianhydrides by the two- and the one-step method. Most of the polyimides could be soluble by one-step method except α,α′-bis(4-aminophenyl)-1,4-diisopropyl benzene/3,3′,4,4′-benzophenonetetracarboxylic dianhydride system in limited organi…
Vulcanization of carboxylated nitrile rubber (XNBR) with different vulcanizing agents (i.e., zinc peroxide, sulphur, and a zinc peroxide–sulphur mixed system) was studied. Properties of the vulcanized compounds depend on the type of crosslinking produced (i.e., ionic or covalent) rather than the crosslinking density.…
The mechanical properties (tensile, flexural modulus, and impact strength) and the flame retardance of glass fiber-reinforced novolac-type phenolic resin modified with polyamide (PA-6, PA-66) were investigated. Results show that polyamide improves the mechanical properties of composites, especially for the impact stre…
A series of soy-based copolyamides with different amino acid contents was synthesized by a condensation polymerization technique. The physical properties and enzymatic degradation properties were investigated. It was found that the introduction of amino acids into this type of copolyamide does not enhance the biodegra…
The effects of 60Co γ-radiation on the properties of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), including the chemical, mechanical, and thermal properties, were investigated. Molecular weight of the irradiated PHBV as measured using a Ubbelohde-type capillary viscometer decreased significantly. Fourier transform…
In linear response, the complex heat capacity is equal to the entropy compliance divided by temperature. The fluctuation dissipation theorem gives a relation to the correlation function (time domain) or spectral density (frequency domain) of entropy fluctuations. Another formal description of frequency dependent heat…
The thermal degradation of plasticized polyvinyl chloride (plastisol) is reported here. Plastisols used in the present work were prepared with the plasticizer diethylhexyl phthalate in different proportions. Thermogravimetric analysis has been applied to study the behavior of plastisols at high temperatures and to eva…
The compatibilization of the polymer blend polyamide 6/poly(phenylene oxide) (PA-6/PPO) system has been studied using the reactive random copolymer styrene–maleic anhydride (SMA) as a compatibilizer precursor. SMA is miscible with PPO when the MA content of SMA is not higher than 8 wt %. The anhydride groups of SMA re…
Three high-level correlated ab initio studies have recently been performed on the electronic absorption spectrum of free base porphin (FBP), but significant differences between the various assignments of the low-lying bands remain. In view of the importance of FBP as the basic building block of the porphyrins, further…
Atmospheric pressure glow plasma was used to modify the inner surface of a commercially available poly(vinyl chloride) (PVC) tube sample to enhance the biocompatible properties by polymerizing tetrafluoroethylene (TFE). The composition and properties of the modified surface were similar to those of PTFE. X-ray photoel…
The preparation and coating of nickel on amorphous and crystallized alumina were carried out by employing a sonochemical method. The interaction between the nickel as well as its oxide and the alumina core was then studied by TEM, XRD, DSC, DRS, FTIR, and magnetization measurements. The following were found: (1) Amorp…
Strongly distorted RNiO 3 (R = Gd, Dy) perovskites, containing Ni 3+, have been prepared under high-pressure conditions: 90 MPa of O 2 pressure (R = Gd) or 2 GPa of hydrostatic pressure in the presence of KClO 4 (R = Dy). These materials have been characterized by X-ray diffraction, neutron powder diffraction (NPD) (f…
Room-temperature single-crystal X-ray structure determinations are recorded for a number of adducts of hydrated lanthanoid(III) chlorides with 2,2'-bipyridine, ‘bpy’, crystallized from water/ethanol solutions, which contain mononuclear arrays with 1 : 1 Ln/bpy stoichiometry. Extended isomorphous series have been defin…
Room-temperature single-crystal X-ray structure determinations are recorded for (hydrated) lanthanoid(III) nitrate/2,2':6',2"-terpyridine (‘tpy’) (1 : 1) complexes; all are of the form Ln(NO3)3/tpy/H2O(1 : 1 : x ), [(tpy)Ln(O2NO)2(OH2)y](NO3)(. z H2O), and form two series of compounds. For Ln = La(-)Gd, the complexes…
Room-temperature single-crystal X-ray structural characterizations are recorded for hydrated lan- thanoid(III) bromide/2,2':6',2"-terpyridine (tpy) (1 : 1) complexes, showing all to be ionic and of the form [(tpy)Ln(OH2) x ]Br3. y H2O, where x and y are 6 and 1 for the isomorphous series Ln = La(-)Er (and intermediate…