Scanning electron microscopy (SEM) images were obtained
on a field emission scanning electron microanalyzer (Zeiss
Supra 40) at an acceleration voltage of 5 kV. Transmission
electron microscope (TEM) was operated on a Hitachi H7650
transmission electron microscope with CCD imaging system
on an acceleration voltage of 120 kV. High-resolution transmission
electron microscope (HRTEM) and Energy filter TEM
(EFTEM) mappings were carried out on a JEM-ARM 200F
Atomic Resolution Analytical Microscope. The powder X-ray
diffraction (XRD) studies were performed on a Philips X’Pert
Pro Super X-ray diffractometer equipped with graphite
monochromatized Cu Kα radiation (λ=1.541841 Å). X-ray