CuInS2 (CIS) quantum dots (QDs) with different diameters were prepared and their optical properties were studied. The optical band gap of QDs, as estimated by absorption spectrum, was found to decrease with increase in size. The stokes shift between absorption and photoluminescence peaks was observed to be larger (>100 meV) in all the three samples. This shows that the defect states available in the forbidden gap dominates the recombination mechanism. The variation in the emission peak with QD size, however, indicates that the relaxation dynamics in CIS QDs involves both excitonic level as well as the defect states.

The magnetic properties of Sr3SnO (SSO) epitaxial thin films prepared under various post-growth annealing treatments are reported. The SSO films are grown on cubic yttria-stabilized zirconia Si (001) platform by pulsed laser deposition. Post-growth vacuum annealing is found to enhance the room-temperature ferromagnetism (RTFM), whereas oxygen annealing reduces it. The results are explained through the oxygen vacancy constituted bound magnetic polarons (BMP) model. An empirical relationship between the extracted BMP concentration and the oxygen vacancy concentration is shown using X-ray photoelectron spectroscopy data. The results indicate a promising way to tune RTFM by manipulating oxygen vacancies and related defects.

The paper describes a new technique of molten salt synthesis (MSS) that is based on the direct oxidation of halide ions with molecular oxygen in thermally stable halide melts to prepare nanoparticles of complex oxides. Lithium cobaltate (LiCoO2) was chosen as a model compound for testing this method. Synthesis was achieved in LiCl–CoCl2 melts at 600 and 700 °C, respectively, under a dry-air atmosphere. Fourier transform infrared (FTIR) and Raman spectroscopies, x-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to study the products obtained. The route suggested results in the formation of stoichiometric high-temperature (HT) LiCoO2 powders.

We describe a new protocol for testing coating/substrate interfacial failures through compression loading of micro-pillars containing an inclined interface region, experimentally realized in the TiN/Ti/Si(100) system. Interfacial failures were achieved through direct compression loading in the axial direction, which yielded reproducible failure stresses which exhibited little dependence on the pillar diameter. The testing protocol lends itself to high-resolution analysis of failure surfaces, and is conducive to correlating interfacial structure and chemistry with mechanical failures within the coating/substrate interfacial region.

Mechanical strain triggers changes in inherent molecular structure, especially in polymeric and biological materials. Unlike conventional techniques, we demonstrate a novel dynamic mechanical characterization method to study the effect of this structural evolution with strain on elastic properties. During tensile characterization of small diameter fibers, we quantitatively measured the viscoelastic properties as a continuous function of strain. While this approach is useful to characterize the elastic properties of metal microwires independent of applied strain, it is extremely important for fundamental understanding of molecular changes and their effect on the viscoelastic properties in materials such as polymer fiber and spider silk.