Synthesis of Si/MgO/Mg2SiO4 Composite from Rice Husk-Originated Nano-Silica

Document Type: Research Paper


School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O.Box: 11155-4563, Tehran, Iran.


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.


1. Chandrasekhar SA, Satyanarayana KG, Pramada PN, Raghavan P, Gupta TN. Review processing, properties and applications of reactive silica from rice husk—an overview. Journal of Materials Science. 2003;38(15):3159-68.
2. Omatola KM, Onojah AD. Elemental analysis of rice husk ash using X-ray fluorescence technique. International Journal of Physical Sciences. 2009;4(4):189-93.
3. Soltani N, Bahrami A, Pech-Canul MI, González LA. Review on the physicochemical treatments of rice husk for production of advanced materials. Chemical Engineering Journal. 2015;264:899-935.
4. Zamani C, Nazarpour S, Abdollahzadeh-Ghom S, Cirera A. Micro and Mesoporous Materials for Emerging Applications. Recent Patents on Materials Science. 2010;3(1):57-67.
5. Bansal V, Ahmad A, Sastry M. Fungus-mediated biotransformation of amorphous silica in rice husk to nanocrystalline silica. Journal of the American Chemical Society. 2006;128(43):14059-66.
6. NuLi Y, Yang J, Wang J, Li Y. Electrochemical intercalation of Mg2+ in magnesium manganese silicate and its application as high-energy rechargeable magnesium battery cathode. The Journal of Physical Chemistry C. 2009;113(28):12594-7.
7. Kohandehghan A, Kalisvaart P, Kupsta M, Zahiri B, Amirkhiz BS, Li Z, Memarzadeh EL, Bendersky LA, Mitlin D. Magnesium and magnesium-silicide coated silicon nanowire composite anodes for lithium-ion batteries. Journal of Materials Chemistry A. 2013;1(5):1600-12.
8. Della VP, Kühn I, Hotza D. Rice husk ash as an alternate source for active silica production. Materials Letters. 2002;57(4):818-21.
9. Chandrasekhar S, Pramada PN, Majeed J. Effect of calcination temperature and heating rate on the optical properties and reactivity of rice husk ash. Journal of Materials Science. 2006;41(23):7926-33.
10. Bao Z, Weatherspoon MR, Shian S, Cai Y, Graham PD, Allan SM, Ahmad G, Dickerson MB, Church BC, Kang Z, Abernathy Iii HW. Chemical reduction of three-dimensional silica micro-assemblies into microporous silicon replicas. Nature. 2007;446(7132):172-5.
11. Will G. Powder diffraction: The Rietveld method and the two stage method to determine and refine crystal structures from powder diffraction data. Springer Science & Business Media; 2006.
12. Liu N, Huo K, McDowell MT, Zhao J, Cui Y. Rice husks as a sustainable source of nanostructured silicon for high performance Li-ion battery anodes. Scientific Reports. 2013;3:1919:DOI: 10.1038/srep01919.
13. Szczech JR, Jin S. Nanostructured silicon for high capacity lithium battery anodes. Energy & Environmental Science. 2011;4(1):56-72.
14. Kim H, Lee EJ, Sun YK. Recent advances in the Si-based nanocomposite materials as high capacity anode materials for lithium ion batteries. Materials Today. 2014;17(6):285-97.