Materials Literature
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In the past, amorphous layers have been described as n or p type according to their majority carriers. The majority carrier type varies from one study to another, even with films of the same composition, which is a very serious problem. In this paper we explain this discrepancy by demonstrating that microcrystallite i…
Five absorption bands with peaks at , 246 nm, 284 nm, 296 nm, and 368 nm were observed at room temperature for Ce-doped (CYA) crystals grown in a reducing atmosphere. Excitation at wavelengths below of Ce:CYA crystals produces a broad luminescence band with a peak at . The excitation spectrum of the luminescence detec…
We report on the growth of cubic boron nitride films on {100} silicon using a low density, supersonic plasma jet generated by a direct-current arc discharge expanded to low pressures. The arc discharge was operated on source gas mixtures of nitrogen and argon, with boron trichloride injected downstream of the expansio…
Conversion of energy from a heat pulse to acoustic stress is theoretically and experimentally studied in detail. The heat pulse was generated by laser radiation delivered via an optical fiber into an absorbing liquid. The experimental results indicate that tensile stress and cavitation are induced in front of the fibe…
The initial growth mode of indium tin oxide on glass was studied. An interesting transition from a 3D island growth mode at low temperatures to 2D growth at higher temperature was observed. This transition from the Volmer-Weber mechanism to the Frank–van der Merwe mechanism occurs at about 150°C. It coincides with the…
We report a neutron and x-ray Rietveld analysis of strontium titanate down to 1.5 K. The results do not show evidence for any supplementary structural phase transition or local frozen polar ordering. These results are a supplementary indication that at very low temperature strontium titanate should display only weak l…
Spherical MnAs ferromagnetic particles with controllable diameters (5–30 nm) are embedded in a high quality GaAs matrix. The particles are formed in a two step process consisting of the epitaxy of a homogeneous Ga1−xMnxAs layer at low temperatures using molecular beam epitaxy followed by phase separation upon annealin…
In 1953, Ter-Mikaelian predicted that low energy bremsstrahlung from relativistic electrons moving through a medium is suppressed, because of interactions between the emitted photon and the electrons in the medium. This suppression occurs because the emission takes place on a long distance scale, allowing for destruct…
The accelerated photoaging of solid and liquid silicones is reviewed, and particular attention is paid to the influence of the main substituents of silicone chemistry. The decomposition of functional groups as -H, -CH=CH 2, -CH 2 -CH 2 -, -CH 2 -CH 2 -CH 2 OH, and -Ph was followed mainly by Fourier transform IR, 1 H-,…
With a view to developing new materials for technological applications, the theory and mechanism of nonlinear optical phenomena in various dielectric media are reviewed. The role of theoretical modeling in advancing our understanding of the structure-property relationships of nonlinear optical materials is discussed.
A range of analytical techniques was used to characterize the conversion products of a common polyolefin processing stabilizer (Irgafos 168, a hindered phosphite) and a common polyolefin antioxidant (Irganox 1076, a hindered phenol). Analysis by gas chromatography (GC)-mass spectrometry revealed that the phosphite sta…
We used temperature and time-dependent changes in vinyl and vinylidene concentration to develop a kinetic model that allows estimation of whether cross-linking or thermal scission will dominate during melt processing of major classes of polyethylenes (PE). Torque rheometer processed high-density, linear low-density-,…
Poly(aryl ethers) are an important class of commercial polymers and are a member of the family of materials referred to as engineering thermoplastics ( 1 ). Commercial examples include Amoco's poly(aryl ether sulfone) (Udel), ICI's poly(ether ether ketone) (PEEK), and General Electric's Ultem poly(ether imide). They d…
It is generally recognized that in order to improve the environmental acceptability of household laundry detergents, biodegradble replacements for the polycarboxylate components of these detergent formulations are needed. Although the poly(acrylic acid) homopolymers and copolymers currently in use are not considered h…
The changes in mechanical properties of several polymers induced by high energy protons (10, 30 and 45 MeV protons) were studied and compared with those induced by 2 MeV electrons and Co-60 gamma rays. Changes in elongation at break showed the same trends for 10 MeV proton and electron irradiations in the case of both…
Density-functional theory (DFT) is a promising method for the calculation of molecular optical properties, since it is less computationally demanding than other ab initio methods, yet typically yields results of a quality comparable to or better than those from the Hartree-Fock approximation. The calculation of static…
This survey concerns the major features of stability, thermal degradation, and stabilization of poly(vinyl chloride) (PVC). The effect of microstructure and chain defects of PVC on the stability of the resin is analyzed and reviewed in the light of recent findings. New experimental results of thermal degradation of PV…
We describe a study aimed at validating the Arrhenius lifetime prediction methodology. Ultimate tensile measurements were made on three elastomers after elevated temperature exposures. Although tensile elongation could be analyzed using the Arrhenius approach, tensile strength could not. Modulus profiles resolved this…
With a view to developing new materials for technological applications, the theory and mechanism of nonlinear optical phenomena in various dielectric media are reviewed. The role of theoretical modeling in advancing our understanding of the structure-property relationships of nonlinear optical materials is discussed.
Sterically hindered phenols are efficient stabilizers against the degradation of polymers upon processing of the melt. They also protect the polymer during end-use and impart protection against the loss of chemical, physical, and aesthetic properties. Combinations of sterically hindered phenols with hydroperoxide deco…