synthesis of si/mgo/mg2sio4 composite from rice husk-originated nano-silica

Silica exists in rice husk, an agriculture waste, as a naturally occurring phase. in first step, acidic pretreatment and calcination of the rice husk were performed to obtain nanosilica, in which various sizes of the nanosilica, totally with sizes under 80 nm, were achieved. second, to reduce nanosilica to elemental si and subsequently formation of the composite, mg used as the reducing agent. in this work, the asobtained composite mainly is the product of magnesiothermic reduction reaction of the nanosilica, which finally resulted in formation of elemental si (silicon), mgo (magnesia) and mg2sio4 (magnesium silicate). the assynthesized composite can be used as anode in lithium ion batteries. the products in each step were characterized using xray powder diffraction (xrd) and scanning electron microscopy (fesem and hrsem) techniques. xray powder diffraction patterns confirmed the formation of almost amorphous silica while the fesem images were representing the spherical silica particles at various calcination temperatures. after the magnesiothermic reduction process, hrsem micrographs indicated the formation of simgomg2sio4 composite with particle sizes of 180300 nm. the phase composition analysis was calculated by rietveld method the electrical response of the si/mgo/mg2sio4 composite was measured to be of 6×10^8 ω.m resulted from i-v measurement.