X-ray powder diffraction (XRD) analysis was carried out using
Rigaku, RINT-2200/PC system with a Cu K irradiation source
( = 1.5405 Å) at 40 kV and 50mA for samples after milling and
milled samples after the heating operation. Samples were analyzed
in a continuous scan mode between 5◦ and 65◦ 2.