Self-assembled arrays of ZnO nanoparticles and their application as varistor materialsElectronic supplementary information (ESI) available: XRD plots and FESEM images. See http://www.rsc.org/suppdata/jm/b4/b400927d/

Abstract

Linear arrays of ZnO nanoparticles have been successfully prepared by a simple sol-gel condensation reaction involving chemical modifiers, followed by drying (80 uC) and calcination (500 uC). The calcined material (nanoarray ZnO) is composed of approximately spherical nanoparticles of average diameter 21 ¡ 3 nm, selfassembled to form arrays extending in length to 2-4 mm. The morphology of the ZnO is found to depend sensitively on the amounts of chemical modifiers present. In their absence the ZnO produced (nano-ZnO) is an unstructured agglomerate of nanoparticles. The mechanism for formation of these linear arrays has been investigated by examining the intermediates formed at 80 uC and 250 uC using XRD and TEM and by following the decomposition reactions using TGA and DSC. Varistors prepared from the nano-array ZnO by sintering (1050 uC) with appropriate mixtures of metal oxides showed a breakdown voltage of 786 ¡ 30 V mm 21 , which is substantially higher than that of samples prepared under similar conditions from either micron-sized commercial ZnO (507 ¡ 30 V mm 21 ) or from nano-ZnO (683 ¡ 30 V mm 21 ).{ Electronic supplementary information (ESI) available: XRD plots and FESEM images. See

Synthesis of High-Temperature Stable Anatase TiO2 Photocatalyst

“…The current investigation also showed that a modifier, urea, can extend the anatase formation to higher temperatures without using any metal or metal oxide dopants. It was previously proved that the precursor processing conditions could influence significantly the high-temperature properties of various nanocrystalline metal oxides such as ZnO. − It should also be noted that the high-temperature anatase phase stability has been achieved previously by using copper sulfate as a dopant precursor . However, when a precursor without any metal ions (1:1 Ti(OPr) 4 :H 2 SO 4 ) was used a major rutile phase was (63%) formed at 800 °C (Supporting Information Figure 12).…”

Heterogeneous Wet Chemical Synthesis of Superlattice-Type Hierarchical ZnO Architectures for Concurrent H2 Production and N2 Reduction

“…Figure b shows the fusion of three prominent lattice planes (101), (100), and (002) along the interfaces creating the grain boundaries. This observation can be explained by the thermal fusion of adjacent particles, probably caused initially by ions diffusing along the interfaces to the points of contact between particles. ,,, This induces bridging and connection of the grains and results in the fusion of contiguous particles generating grain boundaries. The calculated lattice parameters from HR-TEM are in good agreement with that of the corresponding JCPDS file no.…”

“…The precursor of ZnO in the present study was zinc oxalate. Zinc oxalate as a precursor for ZnO-based materials are reported for various applications. – The use of the wet etching method and the precipitation method implemented in the present study differs in the growth kinetics of this precursor and thus becomes a determining factor in the final texture and morphology. Commercial ZnO obtained from M&B Laboratories, U.K., was also characterized and used for activity studies.…”

Preparation of Ni/MgOZrO2 nanocrystals by citrate sol–gel method

“…Metal oxide nanoparticles comprise one important class of such materials, and have favorable optical, magnetic and electronic properties. These properties make these oxides useful for a wide range of applications such as catalysts [1], sensors [2], optical materials [3], electronic materials [4] and magnetic storage [5].…”