Yale University

Dragos Ciuparu

Lisa D Pfefferle

Gary L Haller

Jung Han

A process for growth of boron-based nanostructures, such as nanotubes and nanowires, with a controlled diameter and with controlled chemical (such as composition, doping) as well as physical (such as electrical and superconducting) properties is described. The boron nanostructures are grown on a metal-substituted MCM-41 template with pores having a uniform pore diameter of less than approximately 4 nm, and can be doped with a Group Ia or Group IIa electron donor element during or after growth of the nanostructure. Preliminary data based on magnetic susceptibility measurements suggest that Mg-doped boron nanotubes have a superconducting transition temperature on the order of 100 K.

Growth of boron nanostructures with controlled diameter

Superconducting boron nanostructures

Transition metal-substituted MCM-41 framework structures with a high degree of structural order and a narrow pore diameter distribution were reproducibly synthesized by a hydrothermal method using a surfactant and an anti-foaming agent. The pore size and the mesoporous volume depend linearly on the surfactant chain length. The transition metals, such as cobalt, are incorporated substitutionally and highly dispersed in the silica framework. Single wall carbon nanotubes with a narrow diameter distribution that correlates with the pore diameter of the catalytic framework structure were prepared by a Boudouard reaction. Nanostructures with a specified diameter or cross-sectional area can therefore be predictably prepared by selecting a suitable pore size of the framework structure.

Growth of nanostructures with controlled diameter

A transition metal substituted, amorphous mesoporous silica framework with a high degree of structural order and a narrow pore diameter distribution (&#xb1;0.15 nm FWHM) was synthesized and used for the templated growth of single walled carbon nanotubes (SWNT). The physical properties of the SWNT (diameter, diameter distribution, electronic characteristic) can be controlled by the template pore size and the pore wall chemistry. The SWNT can find applications, for example, in chemical sensors and nanoscale electronic devices, such as transistors and crossbar switches.

Controlled growth of single-wall carbon nanotubes

A transition metal substituted, amorphous mesoporous silica framework with a high degree of structural order and a narrow pore diameter distribution (&#xb1;0.15 nm FWHM) was synthesized and used for the templated growth of GaN nanostructures, such as single wall nanotubes, nanopipes and nanowires. The physical properties of the GaN nanostructures (diameter, diameter distribution, electronic characteristic) can be controlled by the template pore diameter and the pore wall chemistry. GaN nanostructures can find applications, for example, in nanoscale electronic devices, such as field-emitters, and in chemical sensors.

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New Haven, CT, United States of America

Dragos Ciuparu