Materials Literature
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Zn 1 − x Mn x O diluted magnetic semiconductor single phase thin films have been grown by the MOCVD technique. Depositions have been done on fused silica and (0001)-sapphire substrates. Layers on silica are polycrystalline with [001] preferential orientation, while Zn1−xMnxO films on c-sapphire are highly (0001) textu…
Ferromagnetic V-doped ZnO films were fabricated by the conventional pulsed-laser deposition technique on R-cut sapphire substrates from a ceramic target that was made by sol-gel method. All films are highly crystallized to be wurtzite. V-doped ZnO thin films grown at 600–650°C show room-temperature ferromagnetism alon…
Using poly(5-{[(4'-heptoxy-4-biphenylyl)carbonyl]oxy}-1-pentyne) as an example, we demonstrate the incorporative accommodation of the rigid polyacetylene backbones and the mesogenic pendants, which leads to a highly ordered smectic (Sm) phase with a frustrated structure. The polymer exhibits a recognizable sheetlike m…
Abstract This study reports the glass transition temperature ( T g ), and sorption and diffusion of subcritical CO 2 gas in polymethyl methacrylate (PMMA) nanocomposites containing organically modified smectite clay, Cloisite 20A (C20A). A range of methods for preparing the PMMA‐clay nanocomposites was investigated an…
Continuous product development and technology integration efforts using shape memory polymers (SMPs) have uncovered a need for faster response times. As with most smart materials, SMP responds to a specific stimulus. Traditionally SMP is triggered by thermal stimulus; increasing the temperature of the SMP above a Tg w…
Visible electroluminescence from silicon nanocrystals (Si-NCs) embedded in amorphous silicon nitride (a-SiNx) films has been observed. The Si-NC∕a-SiNx films were deposited by evaporating silicon from electron gun into the inductively coupled plasma of nitrogen. The density of Si-NCs in the a-SiNx matrix was around 10…
ABSTRACT The present work aims to provide evidence of corrosion‐induced hydrogen embrittlement of the aircraft aluminium alloy 2024. An extensive experimental investigation involving metallographic and fractographic analyses as well as mechanical testing was performed. The corrosion exposure led to a moderate reductio…
We report that Co0.1Ti0.9O2−δ prepared by the sol-gel technique is a paramagnet following the Curie–Weiss law: χ=χ0+C∕(T+θ) with θ≃5K. However, hydrogenation at 673 K in H2∕Ar(5%∕95%) gas converts a part of the paramagnetic (P) sample to room temperature ferromagnet (RTFM) and reheating the sample at 573 K in air conv…
Abstract Ethylene‐vinyl acetate copolymer (EVA)/montmorillonite (MMT) clay nanocomposites with varying degree of intercalation and exfoliation have been prepared using direct melt blending techniques with various degrees of polarity (9, 18, and 28 wt% vinyl acetate [VA]) and two different types of clay modification. M…
We have grown Mn-doped V2VI3 single crystals using the temperature gradient solidification method. We report on the structural and magnetic properties of Mn-doped Bi2Te3, Sb2Te3, Bi2Se3, and Sb2Se3 compound semiconductors. The lattice constants of several percent Mn-doped V2VI3 were slightly smaller than those of the…
A new class of photoactive chiral liquid crystals based on a photoactive nematic host material and a photoinactive chiral dopant was utilized to investigate the behavior of the blues phases when trans-cis isomerization is induced. While the general behavior follows what has been observed in the cholesteric phase, the…
The work reported in this paper aimed at exploring the advantages of using supercritical carbon dioxide (scCO 2 ) as an environmentally benign solvent and swelling agent for carrying out the grafting process of maleic anhydride onto polypropylene in the solid state. The effects of scCO 2 on the melting temperature and…
Room-temperature ferromagnetism has been observed recently in Co and Fe doped SnO2 powders. In Sn0.99Co0.01O2 powders prepared at 600 °C, ferromagnetism emerged following a sharp transition in the M vs H data at a critical field ∼25kOe. Broad susceptibility maxima were observed in ferromagnetic Sn1−xCoxO2 and Sn1−xFex…
We report a new class of nanostructured carbon materials, which couple nanosized diamond with single-walled carbon nanotubes. This exciting material is being produced in our laboratories in a modified CVD reactor by means of reactions between carbon nanopowders and atomic H. Field-emission scanning electron microscopy…
This investigation addresses basic characterization of a shape memory polymer (SMP) as a suitable structural material for morphing aircraft applications. Tests were performed for monotonic loading in high shear at constant temperature, well below, or just above the glass transition temperature. The SMP properties were…
We have studied the structural stability and magnetic properties of SmCo7−xGax compounds using powder x-ray diffraction and magnetic measurements. Gallium as a dopant not only stabilizes the SmCo 1:7 phase but also induces a strong uniaxial magnetocrystalline anisotropy. An anisotropy field as high as 30.7 T is observ…
A novel process for the preparation of acetates of polysaccharides is described herein. The process involves the acetylation of polysaccharides with acetic anhydride in the presence of iodine as a catalyst. No solvent is required to bring about the acetylation. The method is simple, rapid, and characterized by a high…
The influence of Pr ion on the structural and dielectric properties was studied in Sr1−xPrxTiO3 for 0<x<0.075 composition from room temperature to 375°C. X-ray diffraction and x-ray photoelectron spectroscopy studies revealed that the praseodymium ion enters substitutionally in the Sr site with mixed val…
Microcapsules with oil cores and solid polymer shells have been prepared by precipitation of the polymer from the internal phase of an oil-in-water emulsion. The dispersed phase consists of a polymer, a good solvent for the polymer (dichloromethane), and a poor solvent for the polymer (hexadecane). Removal of the good…
Spider silks are among the strongest and toughest known materials, but investigation of these remarkable properties has been confined largely to orb-weaving spiders. We investigated the mechanical performance of silk from the cobweb-weaving spider Latrodectus hesperus. Both silk from the scaffolding region of the web…