2.4.2. Scanning Electron Microscopy (SEM)

SEM images of original size of HNTs and shortened HNTs were analyzed by ImageJ (NIH, Rockville, MD, USA) and also used to measure particle size.

#### 2.4.3. X-ray Diffraction (XRD)

XRD patterns of HNTs were obtained by Bruker D8 Discover diffractometer (San Jose, CA, USA) equipped with a copper anode X-ray source and a general area detector. The power applied for all tests was 40 kV with 40mA.
