Materials Literature
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The dielectric, ferroelectric and piezoelectric properties of barium titanate (BaTiO 3 )-based solid solution, (1- x )BaTiO 3 – x (Bi 1/2 K 1/2 )TiO 3 (0≤ x ≤1) (BT–BKT100 x ), a candidate lead-free piezoelectric ceramic, were studied using a starting material of fine BaTiO 3 powder. The Curie temperature, T c , of th…
Amphiphilic dendrimers with a custom-designed biaryl repeat unit have been synthesized. These dendrimers afford hydrophobic nanocontainers in polar solvents and hydrophilic nanocontainers in apolar solvents. These container properties were investigated using dye incorporation studies. The aggregation states of these d…
Using quantum mechanics we examined critical steps in the growth of single-walled carbon nanotubes (SWCN) for Ni, Co, Pt, Cu, Cr, Fe, Mo, Rh, Pd, and their combinations. This suggests a two-stage mechanism consisting of nucleation of nanotube growth (determining the number of SWCN) and growth with defect repair (deter…
We present a very efficient and accurate method to simulate scanning tunneling microscopy images and spectra from first-principles density functional calculations. The wave-functions of the tip and sample are calculated separately on the same footing, and propagated far from the surface using the vacuum Green's functi…
A general approach to the analysis of optical properties of photonic crystals based on multiple-quantum-well structures is developed. The effect of the polarization state and a non-perpendicular incidence of the electromagnetic wave is taken into account by introduction of an effective excitonic susceptibility and an…
We have designed, synthesized, and evaluated the physical properties of some high birefringence (Δ n ) isothiocyanato biphenyl-bistolane liquid crystals. These compounds exhibit Δ n ∼0.7–0.8 at room temperature and wavelength λ=633 nm. Laterally substituted short alkyl chains and fluorine atom eliminate smectic phase…
Er 3+ -doped ZnO nanocrystals with hexagonal wurtzite structure were prepared by addition of LiOH to Zn−O−Er precursors in ethanol. The well-known green hot band from the 2 H 11/2 → 4 I 15/2 transition in the 520 − 540 nm region and Stokes emissions were investigated. And the blue, green, and red upconversion emission…
Large-scale MoS2 and WS2 inorganic fullerene-like (IF) nanostructures (onionlike nanoparticles, nanotubes) and elegant three-dimensional nanoflowers (NF) have been selectively prepared through an atmospheric pressure chemical vapor deposition (APCVD) process with the reaction of chlorides and sulfur. The morphologies…
A method for engineering the surface chemistry and pore dimensions in porous Si films for the purpose of controlling the loading and release of a hydrophobic drug is described. Loading of the steroid dexamethasone is confirmed by Fourier transform infrared spectroscopy, and the release rates are characterized by obser…
We study the formation of nanostructures with alternating stripes composed of bulk-immiscible adsorbates during submonolayer heteroepitaxy. We evaluate the influence of two mechanisms considered in the literature: (i) strain relaxation by alternating arrangement of the adsorbate species, and (ii) kinetic segregation d…
We present a lattice formulation of a dynamic self-consistent field (DSCF) theory that is capable of resolving interfacial structure, dynamics and rheology in inhomogeneous, compressible melts and blends of unentangled homopolymer chains. The joint probability distribution of all the Kuhn segments in the fluid, intera…
In an earlier paper [K. K. Saha and A. Mookerjee, Phys. Rev. B 70 (2004) (in press) or, cond-mat/0403456] we had presented a formulation for the calculation of the configuration-averaged optical conductivity in random alloys. Our formulation is based on the augmented-space theorem introduced by one of us [A. Mookerjee…
The rapidly expanding research in Spintronics, the electronics utilizing the electron spin instead of its charge, is driven by the very interesting potential applications. The actual task is to develop principles for the spin manipulations in spintronic devices. In this Report we suggest and verify experimentally a co…
We show that the dissipationless spin current in the ground state of the Rashba model gives rise to a reactive coupling between the spin and charge propagation, which is formally identical to the coupling between the electric and the magnetic fields in the 2+1 dimensional Maxwell equation. This analogy leads to a rema…
We have explored the low-temperature linear and nonlinear electrical conductance $G$ of metallic carbon nanotubes (CNT's), which were grown by the chemical-vapor deposition method. The high transparency of the contacts allows to study these two-terminal devices in the high conductance regime. We observe the expected f…
Tetraazaporphyrins (TAPs), phthalocyanines (Pcs), naphthalocyanines (Ncs), and anthracocyanines (Acs) with four tert-butyl groups attached at similar positions have been synthesized, and their electronic absorption, magnetic circular dichroism (MCD), IR, and voltammetric properties were studied and interpreted with th…
Natural Na-Wyoming montmorillonite was size fractionated by successive centrifugation. Polydisperse particles with average sizes of 400, 290, and 75 nm were then obtained. As the structural charge of the particles belonging to three fractions (determined by cationic exchange capacity measurements) is the same, such a…
The rubbery epoxy network, based on diglycidyl ether of Bisphenol A (DGEBA) and poly(oxypropylene)diamine (Jeffamine D2000), was reinforced with a nanometer-sized inorganic building blocks polyhedral oligomeric silsesquioxanes (POSS). The organic−inorganic networks contained POSS as pendant units of a network chain or…
Three polar poly(para-phenylene ethynylene)s (PPE) were synthesized by utilizing the Heck-Sonogashira protocol. Two of the PPEs carry beta-glucopyranose substituents. Depending upon the linker used between the glycol units and the backbone, the fluorescence of these PPEs can be quenched by Hg2+ and Pb2+ to a varying d…
We explore the conditions under which colloids can be stabilized by the addition of smaller particles. The largest repulsive barriers between colloids occur when the added particles repel each other with soft interactions, leading to an accumulation near the colloid surfaces. At lower densities these layers of mobile…