The results of the related EDS analysis (Fig. 2(c)–(d)) show that the large light grains (marked as spectrum 1 in Fig. 2(b)) mainly contained W,Mg,O elements with an approximate molar ratio of Tungsten :Magnesium:oxygen¼3:2:12 (actually,lithium cannot be precisely detected by EDS ),and the small dark grains(marked as spectrum 2 in Fig. 2(b)) were dominantly composed of Lithium and oxygen elements