Stable, OH free zinc oxide (ZnO) nanoparticles were synthesized by hydrothermal method by varying the growth temperature and concentration of the precursors. The formation of ZnO nanoparticles were confirmed by x-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) studies. The average particle size have been found to be about 7-24 nm and the compositional analysis is done with inductively coupled plasma atomic emission spectroscopy (ICP-AES). Diffuse reflectance spectroscopy (DRS) results shows that the band gap of ZnO nanoparticles is blue shifted with decrease in particle size. Photoluminescence properties of ZnO nanoparticles at room temperature were studied and the green photoluminescent emission from ZnO nanoparticles can originate from the oxygen vacancy or ZnO interstitial related defects.

A diyne functionalized 4,6-O-benzylidene β-d-galactopyranoside gelator, which can align its diyne motifs upon self-assembly (gelation) have been synthesized. The organogel formed by this gelator undergoes topochemical polymerization to polydiacetylene (PDA) under photoirradiation. This strategically designed gelator has been used to make semi-conducting fabrics. By developing the organogel on the fabrics, the gelator molecules were made not only to self-assemble on the fibers, but also to adhere to fabrics through hydrogen bonding. UV irradiation of the gel-coated fabric/fiber resulted in the formation of PDA on fibers. The benzylidene motif could be deprotected to get PDA with pendant free sugars that strongly bind to the cotton fibrils through multiple hydrogen bonds. Conductivity measurements revealed the semiconducting nature of these fabrics.

No abstract

Nanoparticles of ZnnormalGa2normalO4 and Eu-doped ZnnormalGa2normalO4 were hydrothermally synthesized varying the process parameters, such as the volume ratio of the cation precursor solutions, temperature and time of growth, and dopant concentration. The nanoparticles were structurally characterized by X-ray diffraction, high-resolution transmission electron microscopy, and selected-area electron diffraction. The studies confirmed the formation of spherically shaped ZnnormalGa2normalO4 nanoparticles with the standard spinel structure. Photoluminescence (PL) studies show that Eu-doped ZnnormalGa2normalO4 nanoparticles exhibits a sharp red luminescence due to the intra-4f transitions of Eu3+ ions at an excitation of 397nm . Luminescence quenching is observed in the nanoparticles at higher Eu concentration. The room-temperature PL measurements of pure ZnnormalGa2normalO4 nanocrystals monitored at an excitation wavelength of 254nm gave a peak-shaped spectrum instead of the normally observed bell-shaped spectrum of bulk ZnnormalGa2normalO4 . The bandgap of the ZnnormalGa2normalO4 nanoparticles is blueshifted compared to the bulk material due to quantum confinement effects. Incorporation of Eu in the nanoparticles was confirmed by inductively coupled plasma atomic emission spectroscopic studies.

Eu-doped ZnO nanoparticles were synthesized by hydrothermal method. The Eu-dopant concentration has been varied by varying the amount of Eu-dopant concentration. These nanoparticles were structurally characterized by X-ray diffraction, transmission electron microscopy and selected area electron diffraction and it confirms the formation of nanoparticles having standard wurtzite structure. Photoluminescence studies show that these nanoparticles exhibit a sharp red luminescence due to the intra-4 f transitions of Eu 3+ ions at an excitation of 397 nm and 466 nm. Luminescence quenching is observed in the nanoparticles as the Eu-dopant concentration increases. Incorporation of Eu in the nanoparticles was confirmed by the energy dispersive X-ray studies.