Materials Literature
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Gallium and germanium porphyrin complexes in the lowest excited triplet (T1) state have been studied by time-resolved electron spin resonance (TRESR). It is found that for Ge(TPP)(OH)2 (TPP = dianion of tetraphenylporphyrin) intersystem crossing (ISC) from the lowest excited singlet (S1) state to the T1x and T1y suble…
Molybdate sorption using chitosan sorbents has proved to be strictly controlled by the pH of the solution. Sorption isotherms exhibit a sigmoid trend, which has been correlated to the appearance of polynuclear hydrolyzed species, the most favorable species for sorption on chitosan. Sorption capacity exceeds 7 mmol·g−1…
High-resolution electron energy loss spectroscopy (HREELS) and X-ray photoelectron spectroscopy (XPS) have been used to investigate the adsorption of ferrocene on Ag(100) at 150 K. The HREELS data show that ferrocene adopts an orientation with the molecular axis perpendicular to the Ag(100) surface plane for low expos…
A diamond nucleation site responsible for epitaxial growth of diamond on silicon by chemical vapor deposition (CVD) is identified in high-resolution transmission electron microscopic images. Other sites in the same sample leading to polycrystalline growth, but deleterious to epitaxial CVD growth, are also described. A…
Abstract Since diffraction-line broadening is influenced by structural imperfections and the small size of crystallites (i.e. domains over which diffraction is coherent), powder diffraction is a valuable method for the determination of these properties. The theory of diffraction by imperfect solids was well establishe…
Microcalorimetric and infrared spectroscopic (FTIR) measurements for the adsorption of ethylene on Pd/SiO 2 and Pd/Sn/SiO 2 catalysts (4 wt % Pd, Pd/Sn = 3) have been performed at temperatures of 300, 263, and 233 K. In addition, microcalorimetric measurements were made for H 2 and CO adsorption and FTIR studies were…
A characteristic feature of the Portevin - Le Chatelier effect or the jerky flow is the stick-slip nature of stress-strain curves which is believed to result from the negative strain rate dependence of the flow stress. The latter is assumed to result from the competition of a few relevant time scales controlling the d…
Optical limiting behaviour of suspensions of single-walled carbon nanotubes in water, ethanol and ethylene glycol is reported. Experiments with 532 nm, 15 nsec duration laser pulses show that optical limiting occurs mainly due to nonlinear scattering. The observed host liquid dependence of optical limiting in differen…
Abstract Defect and Microstructure Analysis by Diffraction is focused on extracting information on the real structure of materials from their diffraction patterns. The primary features of a powder diffraction pattern are determined by the "idealized" periodic nature of the crystal structure. With the advent of compute…
The surface of a silica sample (Spherosil) have been modified by means of chemical treatments with sulfuric, phosphoric, and hydrochloric acids and potassium chloride. A sample also has been heated in a furnace at high temperatures. Changes in the degree of hydroxylation have been qualitatively followed by means of IR…
New particulate bianisotropic composites—the magnetostatically controlled bianisotropic materials (MCBMs)—recently have been conceptualized. It becomes clear, however, that the theoretical questions raised in recent publications may be considered as interesting as such, but not very relevant as long as experimental va…
Shape memory alloys are gaining an increased interest as passive as well as active damping materials. This damping ability when applied in structural elements can lead to a better noise control, improved life time and even better performance of the envisaged tools.
In order to describe the thermomechanical properties in shape memory polymer of polyurethane series, a thermomechanical constitutive model was developed. In order to describe the variation in mechanical properties due to the glass transition, coefficients in the model were expressed by a single exponential function of…
On the basis of group theoretical symmetry criteria, the primary and secondary order parameters (OP's) have been identified for the three ferroelastic martensitic transformations that occur in the Au-Cd binary, and in the Ti-Ni-M (M = Fe, At, Cu) pseudo-binary shape-memory alloys, viz (i) from the cubic β 2 austenite…
Degree of the shape memory effect was measured either by bending, tensile and compression tests in the temperature range 77∼300 K. The yield stress increased substantially by the grain size refinement, yet maintaining a good shape memory effect. In addition to usual mentioned slow strain rate tests ( about 10 -3 s -1…
An effect of aging on shape memory behavior was investigated for Mn - 15 at.% Cu alloy. It was revealed that aging of the alloy at 693 K significantly improves both shape memory effect (SME) and reversible shape memory effect (RSME). The reason of improved SME can be attributed to the decrease in the axial ratio, c/a,…
A new model for solute redistribution in cellular or dendritic growth is presented The mass balance is an integral part of the analysis. A definition of the coefficient of redistribution extent within the solid is formulated on the basis of the description of equilibrium crystal growth. A definition of the coefficient…
Morphology and crystallography of twins in the martensite in Ti-Ni and Ti-Pd shape memory alloys are reviewed on the basis of recent electron microscopy observations. It has been confirmed that there are five and three twinning modes in Ti-Ni and Ti-Pd martensites, respectively. The morphology and crystallography of n…
Shape Memory Alloys (SMAs) have become increasingly attractive as embedded actuators in polymers yielding adaptive composite structures. In particular, SMA-elements have been used to actively or passively control shape, elastic modules, internal stress level and damping capacity of such smart composites. In the passiv…
The effect of Ta addition on the microstructure, phase transformation temperature and mechanical properties of Ni 50 Ti 50-x Ta x alloys have been studied in this paper. Beginning with a base composition of Ti 50 Ni 50 , Ti was substituted by Ta up to 15at%. A DSC, an optical microscope and SEM were used to characteri…