Publications

Interaction of as-prepared single-walled carbon nanotubes (SWNTs), containing a mixture of metallic and semiconducting species with the potassium salt of coronene tetracarboxylic acid, I, in an aqueous medium provides a simple method of separating semiconducting and metallic species. The metallic nanotubes precipitate out on interaction with I while the semiconducting nanotubes remain in solution. The method avoids centrifugation and is amenable for large-scale separation and can be used as a routine laboratory procedure. Interestingly, interaction with strong electron acceptor molecules brings about metal-semiconductor transitions in SWNTs.

YMnO3 thin films have been grown on n - type Si substrates by nebulized spray pyrolysis in the Metal - Ferroelectric - Semiconductor (MFS) configuration. The C-V characteristics of the film in MFS structure exhibit hysteretic behavior consistent with the polarization charge switching direction, with the memory window decreasing with increase in temperature. The density of interface states decreases with the increase in the annealing temperature. Mapping of the silicon energy band gap with the interface states has been carried out. The leakage current measured in the accumulation region, is lower in well-crystallized thin films and obeys a space- charge limited conduction mechanism.

No abstract is provided for this article.

Kagomé compounds containing two transition metal ions, CoII and NiII, in different proportions have been synthesized, and their magnetic properties have been found to exhibit interesting differences.

Reaction between zinc cupferron and alkali at the organic–aqueous interface has been investigated in detail. In the presence of an organic amine, this reaction yields ZnO nanorods, the morphology depending on the concentration of reactants. In the absence of the amine, ultrathin films of ZnO are produced. Amazingly, both the nanorods and thin films are single crystalline in nature, even though the synthesis is carried out at room-temperature. Single-crystalline, substrate-free ultrathin films of ZnO, is indeed an extraordinary feature of synthesis at the liquid–liquid interface. Photoluminescence spectra show defect-related bands besides that due to band edge emission. The nanostructures exhibit ferromagnetism due to surface defects.

The covalent functionalization of transition metal dichalcogenides (TMDs) has attracted significant interest because of their novel physicochemical properties for various applications. Herein, we report on amino acid (AA)‐induced solution‐processed simultaneous exfoliation and in situ covalent functionalization of exfoliated molybdenum disulfide (MoS 2 ). Covalent functionalization of MoS 2 with AAs was experimentally validated by various spectrochemical characterization and density functional theory calculations. We find that N terminal binding (NH 2 ) of AAs with sulfur defects on exfoliated MoS 2 is much more favorable than the C terminal binding (COOH). Notably, the MoS 2 flakes have significantly improved biocompatibility with normal intestinal epithelial cell‐6. This exfoliation technique is presented here as general strategy; it is not limited to MoS 2 and may apply to exfoliating other MX 2 compounds of TMDs.

No abstract is provided for this article.

The grazing incidence x-ray scattering results presented here show that the self-assembly process of HgSe nanocrystals formed at a liquid-liquid interface is quite different along the in-plane direction and across the interface. In situ x-ray reflectivity and ex situ microscopy measurements suggest quantized out-of-plane growth for HgSe nanoparticles of a size of about [Formula: see text] nm initially. Grazing incidence small-angle x-ray scattering measurements for films transferred from the water-toluene interface at various stages of reaction show that these nanoparticles first form random clusters with an average radius of 2.2 nm, giving rise to equally spaced rings of several orders. Finally, these clusters self-organize into face-centered cubic superstructures, giving sharp x-ray diffraction peaks oriented normal to the liquid-liquid interface with more than 100 nm-coherent domains. We also observed the x-ray diffraction pattern of the HgSe crystalline phase, with the superlattice peaks in these grazing incidence measurements of the transferred films. The electron microscopy and atomic force microscopy results support the x-ray observation of the self-organization of HgSe nanocrystals into close-packed superlattices. These results show that capillary wave fluctuation promotes the oriented attachment of clusters at the liquid-liquid interface, giving direct experimental evidence of contact epitaxy.