Large-Scale Fabrication of Boron Nitride Nanotubes via a Facile Chemical Vapor Reaction Route and Their Cathodoluminescence Properties

Nanoscale Research Letters, Dec 2011

Cylinder- and bamboo-shaped boron nitride nanotubes (BNNTs) have been synthesized in large scale via a facile chemical vapor reaction route using ammonia borane as a precursor. The structure and chemical composition of the as-synthesized BNNTs are extensively characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and selected-area electron diffraction. The cylinder-shaped BNNTs have an average diameter of about 100 nm and length of hundreds of microns, while the bamboo-shaped BNNTs are 100–500 nm in diameter with length up to tens of microns. The formation mechanism of the BNNTs has been explored on the basis of our experimental observations and a growth model has been proposed accordingly. Ultraviolet–visible and cathodoluminescence spectroscopic analyses are performed on the BNNTs. Strong ultraviolet emissions are detected on both morphologies of BNNTs. The band gap of the BNNTs are around 5.82 eV and nearly unaffected by tube morphology. There exist two intermediate bands in the band gap of BNNTs, which could be distinguishably assigned to structural defects and chemical impurities.

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

https://link.springer.com/content/pdf/10.1007%2Fs11671-010-9794-8.pdf

Large-Scale Fabrication of Boron Nitride Nanotubes via a Facile Chemical Vapor Reaction Route and Their Cathodoluminescence Properties

Bo Zhong 0 2 Xiaoxiao Huang 0 2 Guangwu Wen 0 1 2 Hongming Yu 0 2 Xiaodong Zhang 0 2 Tao Zhang 0 2 Hongwei Bai 0 2 0 School of Materials Science and Engineering, Harbin Institute of Technology , 150001, Harbin, People's Republic of China 1 School of Materials Science and Engineering, Harbin Institute of Technology (Weihai) , 264209, Weihai, People's Republic of China 2 School of Materials Science and Engineering, Harbin Institute of Technology , 150001, Harbin, People's Republic of China Cylinder- and bamboo-shaped boron nitride nanotubes (BNNTs) have been synthesized in large scale via a facile chemical vapor reaction route using ammonia borane as a precursor. The structure and chemical composition of the as-synthesized BNNTs are extensively characterized by X-ray diffraction, scanning electron microscopy, highresolution transmission electron microscopy, and selected-area electron diffraction. The cylinder-shaped BNNTs have an average diameter of about 100 nm and length of hundreds of microns, while the bamboo-shaped BNNTs are 100-500 nm in diameter with length up to tens of microns. The formation mechanism of the BNNTs has been explored on the basis of our experimental observations and a growth model has been proposed accordingly. Ultraviolet-visible and cathodoluminescence spectroscopic analyses are performed on the BNNTs. Strong ultraviolet emissions are detected on both morphologies of BNNTs. The band gap of the BNNTs are around 5.82 eV and nearly unaffected by tube morphology. There exist two intermediate bands in the band gap of BNNTs, which could be distinguishably assigned to structural defects and chemical impurities. - Introduction As structural analogs of carbon nanotubes (CNTs), boron nitride nanotubes (BNNTs) have attracted continuous attention owing to their extraordinary structural and physical properties [1,2]. Similar to CNTs, BNNTs possess a superior Youngs modulus and a high thermal conductivity [3-6]. BNNTs are electrical insulator and transparent to visible light due to a wide band gap (around 5.25.8 eV) that is almost independent of tube chirality [7,8]. Furthermore, BNNTs exhibit excellent chemical stability and inoxidizability [2,9]. The unique structure-induced properties of BNNTs bring a series of opportunities for their potential applications as hydrogen storage media, biological probes, piezoelectric materials, composite reinforcements and harsh-environment semiconductor devices [10-17]. These promises have motivated intense research efforts seeking to develop synthetic strategies for preparing BNNTs. Despite the structural similarity between BNNTs and conventional CNTs, great challenges have been encountered in fabricating BNNTs compared with the relative ease of synthesizing CNTs. Many techniques, such as arc-discharge [1], ball milling and annealing [18-21], laser ablation [22-24], chemical vapor deposition [25,26], oven heating proper B and N containing precursors [27,28], template confining [29,30], and so forth, have been attempted to fabricate the BNNTs in recent years. Although some success has been achieved in producing pure and well-crystallized BNNTs, these techniques generally require special equipments or complex synthesis procedures and the yields of BNNTs are commonly disappointingly low. Here, we describe a facile growth technique that can easily and reliably produce macroscopic amounts (~200 mg per experimental run) of BNNTs with cylinder and bamboo-shaped morphologies. Ammonia borane (AB, H3BNH3), which contains only B, N and H elements, is demonstrated to be an effective starting material for the fabrication of BNNTs. The structures and luminescence performance of the as-synthesized BNNTs have been extensively characterized. A two-step growth model has been established based on the analysis of the structures of BNNTs and the reaction process. The present work provides a facile synthetic approach and a deeper insight into the luminescence performance of BNNTs, which facilitates large-scale production of BNNTs and their application as compact ultraviolet (UV) laser devices. Experimental In this study, we present a simple approach for the fabrication of BNNTs in a gas pressure furnace. Ammonia borane (AB) synthesized according to Ramachandran [31] was used as a starting material, and ferrocene was used as a catalyst. In a typical procedure, AB powder (4.0 g) and ferrocene (1.5 g) were mixed and charged into an graphite crucible of about 2 l capacity using a piece of graphite paper as inner lining, then the crucible was loaded into the furnace chamber. The chamber was sealed and pumped down to a base pressure of 0.1 Pa. Subsequently, 0.8 MPa high pure nitrogen was pressed into the furnace chamber. The furnace was heated to 1,450C at a rate of 10C min-1 and held for 60 min before it was finally cooled to room temperature. The BNNTs were found on the graphite paper. The samples obtained were extensively characterized by scanning electron microscopy (SEM, MX2 (...truncated)


This is a preview of a remote PDF: https://link.springer.com/content/pdf/10.1007%2Fs11671-010-9794-8.pdf

Bo Zhong, Xiaoxiao Huang, Guangwu Wen, Hongming Yu, Xiaodong Zhang, Tao Zhang, Hongwei Bai. Large-Scale Fabrication of Boron Nitride Nanotubes via a Facile Chemical Vapor Reaction Route and Their Cathodoluminescence Properties, Nanoscale Research Letters, 2011, pp. 36, Volume 6, Issue 1, DOI: 10.1007/s11671-010-9794-8