Scanning Electron Microscopy (SEM) Analysis
The surface morphological characteristics of samples with different
thermal treatment were observed using a SU8100 scanning electron
microscope (Hitachi High- Technologies Corporation, Tokyo, Japan). The
sample powder was stuck on a specimen holder using a double-sided
conductive adhesive and then coated with a 10 nm gold film by ion
sputtering. An accelerating voltage of 15 kV was used during
observation.16 The sample images were obtained at a
magnification of 3000 times.