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 pre-treatment and calcination of the rice husk were performed to obtain nano-silica, in which various sizes of the nano-silica, totally with sizes under 80 nm, were achieved. second, to reduce nano-silica to elemental si and subsequently formation of the composite, mg used as the reducing agent. in this work, the as-obtained composite mainly is the product of magnesiothermic reduction reaction of the nano-silica, which finally resulted in formation of elemental si (silicon), mgo (magnesia) and mg2sio4 (magnesium silicate). the as-synthesized composite can be used as anode in lithium ion batteries. the products in each step were characterized using x-ray powder diffraction (xrd) and scanning electron microscopy (fesem and hrsem) techniques. x-ray powder diffraction patterns confirmed the formation of almost amorphous silica while the fe-sem images were representing the spherical silica particles at various calcination temperatures. after the magnesiothermic reduction process, hrsem micrographs indicated the formation of si-mgo-mg2sio4 composite with particle sizes of 180-300 nm. the phase composition analysis was calculated by rietveld method the electrical response of the si/mgo/mg2sio4 composite was measured to be of 6×108 ω.m resulted from i-v measurement.