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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.

Single-phase LaNi 1-x Mn x O 3 samples in the compositional range 0<or=x<or=0.2 were prepared by the decomposition of precursor hydroxide solid solutions, and La 2 NiMnO 6 was prepared from a mixture of carbonates. All the samples contained a disordered array of nickel and manganese ions. X-ray absorption and XPS measurements indicate the presence of Mn(III) and Ni(III) valence states at room temperature for x=0.1, 0.2 and 0.5. Magnetic susceptibility data suggest Mn 4+ solute ions and Stoner-enhanced Pauli paramagnetism of the metallic solvent for x=0.01 with a smooth transition to Mn 3+ solute ions and a spontaneously magnetised solvent conduction band at x=0.05. Below 200K, the x=0.05 sample forms superparamagnetic clusters, and below 40K there is evidence for an antiferromagnet spin-density wave. Comparisons with LaCo 0.95 Mn 0.05 O 3 and La 0.98 Sr 0.02 CoO 3 confirm that the long-range magnetic coupling occurs via solvent electrons in a narrow conduction band. The conductivity changes from that of a narrow-band metal for x<0.01 to that more characteristic of diffusive motion for x>0.05, but any motional enthalpy appears to remain small ( Delta H m approximately=0). The x=0.1 sample exhibits ferrimagnetic spin glass behaviour below 40K, and the ferromagnetic interactions increase with manganese concentration. The oxide with x=0.50 is ferromagnetic with a well defined Curie temperature.

Nanoparticles of CdSe, CdS and ZnSe have been incorporated in the inter-tubular gaps of single-walled carbon nanotube (SWNT) bundles. Electron microscope, X-ray diffraction (XRD), electronic spectroscopy and Raman studies have been employed to characterize these systems. The lengths of the intercalate inside the bundles could be varied by changing the reaction conditions. Electronic absorption and photoluminescence studies from the semiconductor intercalates show the expected blue-shift with respect to the corresponding bulk samples in CdS and ZnS samples. The SWNT lattice is expanded on incorporating CdSe as confirmed by XRD in the low-angle range. The expansion in the lattice is also corroborated by the Raman measurements which show a considerable red-shift for both the radial and the tangential modes of the SWNT signal, thus signifying an increase in the van der Waals gap between the tubes in the bundle. The red-shift of the Raman signal is due to the decrease in the inter-tube interactions as well as due to doping effects.

We have prepared borocarbonitrides of various compositions with extended sheet morphology, by the reaction of few-layer graphene with boric acid and urea at 900°C and characterized them in detail. Supercapacitor performance of the borocarbonitrides has been studied in detail, the composition containing more pyridinc nitrogen exhibiting a specific capacitance of 306F/g at 0.2A/g. This composition also shows good oxygen reduction reaction (ORR) activity with an electron transfer number close to 4. The extended sheet structures of the B x C y N z samples has enabled us to fabricate field-effect transistors. These materials also show reasonable UV photoresponse.

Tunneling spectroscopy measurements have been carried out on a single molecule device formed by two Pd nanocrystals (dia, $\sim$5 nm) electronically coupled by a conducting molecule, dimercaptodiphenylacetylene. The I-V data, obtained by positioning the tip over a nanocrystal electrode, exhibit negative differential resistance (NDR) on a background M-I-M characteristics. The NDR feature occurs at $\sim$0.67 V at 300 K and shifts to a higher bias of 1.93 V at 90 K. When the tip is held in the middle region of the device, a coulomb blockade region is observed ($\pm\sim$0.3 V).

Interaction with electron-donor and -acceptor molecules such as aniline and nitrobenzene brings about marked changes in the D, G, G' and 2D bands of the Raman spectrum and the electronic structure of graphene, prepared by the exfoliation of graphitic oxide.

Effects of cation substitution in the manganese site of charge-ordered (CO) rare earth manganates have been studied to find out how the properties vary with the average radius of theAsite cations, 〈r A 〉, and the substituent cation. The insulating CO state ofLn 0.5Ca0.5MnO3(Ln=Nd, Gd, or Y) is unaffected by substitution with Al3+and Fe3+, but the CO state in the Nd compound (〈r A 〉=1.17 Å) is converted into a ferromagnetic metallic state by Cr3+substitution. Chemical conversion of the charge-ordered state in the insulating manganates by Cr3+substitution seems to occur only when 〈r A 〉≥1.17 Å. Progressive substitution of Mn3+in Nd0.5Sr0.5MnO3(〈r A 〉=1.24 Å) with Al3+and Fe3+renders the material an insulator. Substitution with Cr3+, however, makes it a ferromagnetic metal from 250 K (∼T C) down to low temperatures, without the intervening CO state as in the parent manganate.