Preparation and ultraviolet-visible luminescence property of novel BN whiskers with a Cap-stacked structure

A new kind of boron nitride (BN) whisker with a novel cap-stacked structure and excellent ultraviolet-visible luminescence properties has been successfully prepared via a facile chemical vapor reaction route. SEM analysis shows that the BN whiskers are uniform with a mean diameter of 1 μm and a length up to at least 1 mm. TEM images and the electron diffraction patterns indicate that the BN whiskers are constructed by stacking numerous cap-shaped BN sheets along the axial direction. The BN sheets are almost perpendicular to the whisker axis. The chemical compositions and the bonding characteristics of the BN whiskers are confirmed by EELS, XPS, and FTIR results. The diameters of the BN whiskers could be controlled by tuning the reaction pressure and temperature. The growth mechanism and morphology evolution of the BN whiskers are explained on the basis of the vapor-liquid-solid mechanism. Both photoluminescence and cathodoluminescence spectra of the BN whiskers exhibit broad emission bands from 200 to 700 nm, indicating that they could be used as compact light emitters at both ultraviolet and visible wavelengths.