Templated one-step catalytic fabrication of uniform diameter MgxBy nanostructures

Abstract

Direct fabrication of Mg x B y nanostructures is achieved by employing Ni-Mg incorporated MCM-41 in the Hybrid Physical-Chemical Vapor Deposition (HPCVD) reaction. Different reaction conditions are tested to optimize the fabrication process. TEM analysis shows the fabrication of Mg x B y nanostructures starting at a reaction temperature of 600 C, and the yield of the nanostructures increases with the reaction temperature. The as-synthesized Mg x B y nanostructures have the diameters in the range of 3-5 nm, which do not increase with the reaction temperature. EELS analysis of the template removed nanostructures confirms the existence of B and Mg with minimal contamination of Si and O. NEXAFS and Raman spectroscopy analyses suggested a concentric layered structure for our as-synthesized Mg x B y nanotube/nanowire, which is in good agreement with the theoretical calculations. Ni K-edge XAS indicates that the formation of MgNi alloy particles is important for the Vapor-Liquid-Solid (VLS) growth of Mg x B y nanostructures with fine diameters, and the presence of Mg vapor not just Mg in the catalyst is crucial for the formation of Ni-Mg clusters. Physical templating by MCM-41 might also help to confine the diameter of the nanostructures. DC magnetization measurements indicate possible superconductive behaviors in the as-synthesized sample.

Nanoscaled Metal Borides and Phosphides: Recent Developments and Perspectives

“…Similarly, MgAl x B y nanowires were obtained after treatment of 1% Mg-doped mesoporous alumina under gas mixtures of B 2 H 6 /H 2 or BCl 3 /H 2 , although templating was not clearly demonstrated since 1D nanostructures were obtained outside the mesopores . Some Mg–B nanowires with undefined composition were similarly deposited over an MCM-41 zeolite with metallic nickel filling the pores, by using the reaction between B 2 H 6 /H 2 and Mg vapors from metal ingots . Yang et al described a convenient alternative method to produce MgB 2 nanowires of 100 nm diameter and 10 μm length .…”

Large diameter multiwall nanotubes of MgB2: Structural aspects and stability of superconducting nanotubular magnesium boride

“…As predicted previously [12], the most stable 2D precursor for MgBNT formation is an SL Reports on the synthesis of MgBNT are very rare [23,24,33,34]. Although many sophisticated experimental methods have been developed, it is remarkable that a simple thermal evaporation of MgB 2 powder under a special rapid heating protocol without a catalyst can produce nanoparticles (NP) in an 80 yield [24].…”