Materials Literature
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Dielectric properties of the relaxor ferroelectric ceramics PLZT 8/65/35 and 9.5/65/35 were studied in the broad frequency range of 100 Hz–1 THz at low temperatures below the freezing temperature. Nearly frequency-independent dielectric losses were observed up to 1 GHz on cooling down to 10 K. Their magnitude decrease…
Abstract The solid‐state procedure is used to produce bulk ceramics of CCTO (CaCu 3 Ti 4 O 12 ). The samples of the CCTO ceramic are studied by X‐ray powder diffraction and infrared and Raman scattering spectroscopy. The infrared and Raman scattering spectroscopy confirm the formation of the CCTO phase, as seen by X‐r…
The creation of realistic models of amorphous silica has been studied using the Monte Carlo based method of Wooten, Winer, and Weaire, where the bond-topology is optimized with respect to an interatomic potential model. The commonly used Keating potentials are compared and their strengths and weaknesses are assessed.…
In this letter we report the synthesis of nanostructures of molybdenum trioxides by directly oxidizing a spiral coil of molybdenum, at ambient atmosphere, by passing a current through the coil. The advantage of this approach is that the temperature of the substrate is low (normally below 200°C), and that the nanostruc…
Abstract A family of bisphenol‐containing ligands with XO 2 donor atoms, where X = S, Se, or N, yields [Ni II ] 4 ( 1 ) and ( 2 ), [Ni II ] 5 ( 3 ), and [Ni II ] 6 ( 4 ) complexes. Complex 2 , 3 , and 4 have been structurally characterised by X‐ray diffraction. The compounds were characterised spectroscopically and by…
The first azide(mu1,1)-bridged binuclear cobalt(II) complex with a chelated imino nitroxide radical, [Co2(immepy)2(N3)(4)].2EtOH, was structurally and magnetically characterized, where immepy = 4,4,5,5-tetramethyl-2-(6'-methyl-2'-pyridyl) imidazoline-1-oxyl. Five nitrogen atoms complete the coordination sphere of the…
Magnetic susceptibility and EPR studies show that trinuclear Cu(II)-pyrazolato complexes with a Cu(3)(mu3-X)2 core (X = Cl, Br) are ferromagnetically coupled: J(Cu-Cu) = +28.6 cm(-1) (X = Cl), +3.1 cm(-1) (X = Br). The orderly transition from an antiferromagnetic to a ferromagnetic exchange among the Cu centers of Cu(…
Abstract Thermoplastic starch (MaterBi®) based composites containing flax fibers in unidirectional and crossed‐ply arrangements were produced by hot pressing using the film stacking method. The flax content was varied in three steps, viz. 20, 40 and 60 wt.‐%. Static tensile mechanical properties (stiffness and strengt…
A synthetic route to tubelike mesoporous carbon materials with a cubic structure has been developed by using propylsulfonic acid groups anchored onto a silica wall, which act as an acid catalyst for carbon-source polymerization. Pores with diameters of 2.4 and 4.0 nm were recorded for the carbon replicas obtained afte…
Abstract Hybrid optical films of TiO 2 ‐triethoxysilane‐capped polythiourethane (TCPTU) with high refractive indices have been prepared via an in situ sol‐gel method. The high refractive index triethoxysilane‐capped polythiourethane (TCPTU) was synthesized by polyaddition of the triethoxysilane‐modified trimercaptothi…
New materials are currently sought for use in spintronics applications. Ferromagnetic materials with half metallic properties are valuable in this respect. Here we present the electronic structure and magnetic properties of binary compounds consisting of $3d$ transition metals and group V elements, viz., P, Sb, and As…
Photoinduced phenomena are of general interest for new materials. Recently, photoinduced molecular desorption of oxygen has been reported in carbon nanotubes. Here we present, using thermopower measurements, that carbon nanotubes when exposed simultaneously to UV light and oxygen exhibit photoinduced oxidation of the…
We present a calorimetric study of the phase behavior of octylcyanobiphenyl (8CB) liquid crystal confined to a controlled-pore glass (CPG). We used CPG matrices with characteristic void diameters ranging from 400 to 20 nm. In bulk we obtain weakly first-order isotropic to nematic (I-N) phase transition and nearly cont…
High-performance supercomputing and high-fidelity atomistic methods are used to study the shape effects on the single-particle electronic states of nanocrystals. We found that the shape can be used as an efficient way to control the electronic structures of the nanocrystals. Changing the shape is more flexible and pro…
Motivated by recent measurements of electron paramagnetic resonance (EPR) spectra in modulation-doped CdMnTe quantum wells, [F.J. Teran {\it et al.}, Phys. Rev. Lett. {\bf 91}, 077201 (2003)], we develop a theory of collective spin excitations in quasi-two-dimensional diluted magnetic semiconductors (DMSs). Our theory…
We report a study of the low temperature bulk magnetic properties of the spin ice compound Dy2Ti2O7 with particular attention to the (T < 4 K) spin freezing transition. While this transition is superficially similar to that in a spin glass, there are important qualitative differences from spin glass behavior: the free…
The effect of hole doping on the exchange coupling of the nearest neighbor (NN) Mn pairs in ${\mathrm{Z}\mathrm{n}}_{1\ensuremath{-}x}{\mathrm{M}\mathrm{n}}_{x}\mathrm{T}\mathrm{e}$ is probed by inelastic neutron scattering. The difference in the NN exchange energy $\ensuremath{\Delta}{J}_{1}$ in the presence and in t…
The excited state interaction between CdSe nanocrystals and a hole acceptor, p -phenylenediamine (PPD), is probed using emission and transient absorption spectroscopies. The changes in the photophysical properties of CdSe nanocrystals arising from the interaction with PPD are compared with an aliphatic amine, n -butyl…
The ultrasensitive differential scanning calorimetry is used to observe the glass transition in thin (1-400 nm) spin-cast films of polystyrene, poly (2-vinyl pyridine) and poly (methyl methacrylate) on a platinum surface. A pronounced glass transition is observed even at a thickness as small as 1-3 nm. Using the high…
Silicon nanoparticles with bright visible photoluminescence have been prepared by a new combined vapor phase and solution phase process, using only inexpensive commodity chemicals. CO 2 laser induced pyrolysis of silane was used to produce Si nanoparticles at high rates (20−200 mg/h). Particles with an average diamete…