Search

A newly developed robust strategy that utilizes shape- and size-controlled [beta]-Sn nanocrystals as reactive templates, is presented. The analysis helps in the production of various nanocrystals involving elements of notably different reduction potentials, reduction kinetics and reactivity.

A new low-temperature approach to the synthesis of atomically ordered nanocrystals using bimetallic nanoparticle precursors has been demonstrated. It is expected that approach to the synthesis of atomically ordered nanocrystals will be applicable to a wide range of inorganic solids, perhaps even yielding new metastable solids that are not stable in bulk systems.

Issues concerning the synthesis by topochemical means of three-dimensional perovskites from lamellar Dion-Jacobson and Ruddlesden-Popper starting materials are presented. Oxygen loss accompanying the reduction of one of the ions is used to form the perovskites which keep the anisotropic texture of their layered starting materials.

The synthesis of colloidal GeS and GeSe nanostructures obtained by heating Ge[I.sub.4], hexamethyldisilazane, oelylamine, oleic acid and dodecanethiol or trioctylphosphine selenide is described. Optimal measurements have shown indirect ban gaps for GeS and GeSe and electrical measurements have shown that drop-cast films of GeSe have displayed p-type conductivity.

The chemical synthesis and characterization of [alpha]-Mn nanoparticles in the presence of n-butyllithium as a reducing agent are reported. Oleate ligand bound amorphous manganese oxide layer rendered the nanoparticles air-stable while the oxide-coated [alpha]-Mn nanoparticles are found to be paramagnetic.

Solution chemistry methods are used for preparing bimetallic CuPt alloy nanoparticle catalysts with controllable sized and shapes. The mixed-metal nanoparticles have displayed excellent catalytic properties for CO oxidation, with light-off temperatures that are nearly 200 K below those of conventional supported Pt catalysts.

ZnO nanoparticles, which adopt the wurtzite (WZ) structure, have served as structural templates for the controllable formation of WZ-type ZnS and ZnSe. The results have highlighted the importance of forming WZ-type ZnO as a reaction intermediate in order to preferentially stabilize the WZ forms of ZnS and ZnSe.

The process of transforming single-component metal nano wires into multisegment nanowires with multimetal components is discussed. These solution chemistry conversion reactions provide a cpnvenient tool kit for engineering complex solid-state compoenets into template-grown metal nanowires.

A recently developed kinetically controlled borohydride reduction process, which helps in the chemical synthesis of shape-controlled indium (In) nanoparticles at room temperature, is presented. These nanoparticles are shown to exhibit high conductivity and surface plasmon resonance (SPR) properties, which make them suitable for several optical and magnetic applications.

The shape-controlled conversion of a diverse library of rhodium nanocrystal shapes into dense and hollow [Rh.sub.2]P nanocrystals is described.

A new strategy is described for synthesizing nanostructures of transition metal phosphides, which has used the conversion of preformed metal nanoparticles into metal phosphides by solution-mediated reaction with trioctyphosphine (TOP). The results have shown that in addition to its utility for accessing transition metal phosphides using a highly robust method, various aspects of nanostructure can be influenced by controlling critical aspects of the metal nanoparticle precursors.

An unusual multistep reaction pathway that leads to the formation of AuCuS[n.sub.2], a new ternary intermetallic compound that was discovered as nanocrystals using a low-temperature solution route is described. The multistep reaction pathway provides compelling evidence that a nanocomposite forms in solution and transforms into alloy and intermetallic nanocrystals via solution-mediated reactions.

Nanocrystals of intermetallic compounds undergo facile solution-mediated reactions to form derivative phases, where these intermetallics can be used as reagents for the low-temperature solution synthesis of other intermetallic phases. This work has added to a growing toolbox of low-temperature reactions for accessing nanocrystalline alloys and intermetallics and also has helped in the formation of new and complex solids.

The example of hollow magnetic CoPt nanopheres synthesized through a novel and potentially general one-pot reaction that exploits an in situ sacrificial template is reported. One of the important implications of the successful synthesis of hollow nanospheres of a CoPt allow phase is that the alloy system have received much less synthetic development than single-metal systems.

The study demonstrated that metal nanoparticles could be used as a robust solution-based toolkit for synthesizing intermetallic compounds and alloys within minutes at low temperatures. The strategy exploits the enhanced reactivity and nanoscale diffusion distances afforded by binary nanoparticle composites to eliminate the need for high-temperature heating and atomic-scale homogenization, which are necessary using traditional methods for solid-state synthesis.

Low-temperature solution routes originally developed for the synthesis of nanocrystals and nanocrystalline powders can be exploited to access new ordered intermetallics with ternary compositions. The Au-Cu-Sn system was studied since ternary phase diagrams are difficult to map.