Figure 4
a A typical bright-field TEM image showing the bamboo-shaped BNNTs, upper inset: a representative tip reflecting catalyst extruding; lower inset: a high magnification TEM image of a typical knob. b SAED pattern taken from a catalyst-containing knob marked in part a. HRTEM images taken from the areas framed in part a showing: c defects containing BN walls of a knob encapsulating a catalyst particle, d detailed structure of the joint connecting two bamboo units and e interface between BN sheets and a catalyst particle. f EDX spectrum of the knobs of bamboo-shaped BNNTs. g EELS spectrum collected from tubular part of a bamboo-shaped BNNT.