Formation of SiC whiskers from raw rice husks in argon atmosphere

Krishnarao, R. V.; Mahajan, Y. R.

doi:10.1016/0272-8842(95)00084-4

Cited by 45 publications

(33 citation statements)

References 20 publications

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“…It can be found that the SiC-PRHs and SiC-crucible display strong blue light emission at 446 and 448 nm, respectively. Compared with that of bulk ¢-SiC (519 nm), 17) the PL Journal of the Ceramic Society of Japan 120 [8] 338-340 2012 peak position is considerable blue-shifted, which is attributed to the quantum confinement effect of nanomaterials and involved defects. 18) Furthermore, the SiC-crucible shows higher peak intensity, indicating that the ¢-SiC whiskers have a better light emission performance than the ¢-SiC particles.…”

Section: )16)mentioning

confidence: 99%

Fabrication of nanostructured silicon carbide from rice husks and its photoluminescence properties

Shirai

Fuji

2012

J. Ceram. Soc. Japan

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Nanostructured silicon carbide (SiC) particles and whiskers have been fabricated by pyrolysis of rice husks (RHs) in argon atmosphere. The results revealed that a complete carbothermal reduction of silica was achieved at 1600°C for 2 h and the final product was ¢-SiC. The ¢-SiC obtained on the bodies of pyrolyzed rice husks (PRHs) was mainly particles having diameters of 100200 nm and the wool-like product formed on the inner walls of the graphite crucible was ¢-SiC whiskers with diameter of around 170 nm and tens of micrometers in length. Compared to bulk ¢-SiC, down-shifts and asymmetric broadening were observed on both transverse optical (TO) and longitudinal optical (LO) phonon peak in Raman scattering spectra of the nanostructured SiC. The photoluminescence (PL) spectra revealed that the nanostructured ¢-SiC, especially the ¢-SiC whiskers, showed excellent blue light emission property. The PL emission peak was considerable blue-shifted relative to that for the bulk ¢-SiC. ©2012The Ceramic Society of Japan. All rights reserved.Key-words : Rice husks, ¢-SiC, Particles, Whiskers, Blue light emission [Received April 23, 2012; Accepted May 28, 2012] Recently, the photoluminescence properties of SiC have received considerable attention. Compared with bulk crystal SiC, SiC nanostructures show more excellent optical performance because of their low dimensionality, quantum confinement and shape effects. 1)3) Up to now, much effort has been devoted to fabricate various kinds of SiC nanostructures with special optical properties. For example, Xi et al. synthesized ¢-SiC nanorods, nanoneedles by a magnesium-catalyzed co-reduction route, displaying excellent and shape-dependent optical properties. 4)Wu et al. synthesized twinned zigzag SiC nanoneedles with SiC nanoparticles aggregates as byproducts via silicon evaporation onto multiwall carbon nanotubes and this kind of nanostructured SiC showed considerable blue shifts of multi-PL peaks relative to the bulk ¢-SiC.5) Niu et al. employed thermal evaporation of ZnS and carbon on silicon wafer to produce ¢-SiC nanowires arrays and show a blue emission luminescence at 430 nm. 6) Li et al. synthesized ¢-SiC nanospheres and nanowires by a metal coreduction method, showing a wide blue emission luminescence centered at 443 nm.7) Even though they were basically successful, most of them involve complex procedures, extra metal catalyst or expensive precursors.As we known, huge amounts of rice husks (RHs) are produced annually in the world as an agricultural byproduct of rice threshing. RHs have been proved to be an economical and promising raw material for producing SiC, due to high surface area and intimate contact available for carbon and silica. 8)12) However, few literatures are accessible about optical properties of SiC that fabricated by pyrolysis of RHs. In this study, nanostructured ¢-SiC particles and whiskers were prepared by using RHs as precursors. The microstructure and optical properties of the ¢-SiC were studied.RHs were collected from a local rice mill factory o...

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Section: )16)mentioning

confidence: 99%

Fabrication of nanostructured silicon carbide from rice husks and its photoluminescence properties

Shirai

Fuji

2012

J. Ceram. Soc. Japan

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“…The SiC whiskers are then used to reinforce ceramic cutting tools, increasing their strength tenfold [9].…”

Section: Sic Productionmentioning

confidence: 99%

Rice Husk Ash

Ramezanianpour

2013

Springer Geochemistry/Mineralogy

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IntroductionRice-husk (RH) is an agricultural by-product material. It constitutes about 20 % of the weight of rice. It contains about 50 % cellulose, 25-30 % lignin, and 15-20 % of silica. When rice-husk is burnt rice-husk ash (RHA) is generated. On burning, cellulose and lignin are removed leaving behind silica ash. The controlled temperature and environment of burning yields better quality of rice-husk ash as its particle size and specific surface area are dependent on burning condition. For every 1000 kg of paddy milled, about 200 kg (20 %) of husk is produced, and when this husk is burnt in the boilers, about 50 kg (25 %) of RHA is generated. Completely burnt rice-husk is grey to white in color, while partially burnt ricehusk ash is blackish [1][2][3].Rice-husk ash (RHA) is a very fine pozzolanic material. The utilization of rice husk ash as a pozzolanic material in cement and concrete provides several advantages, such as improved strength and durability properties, reduced materials costs due to cement savings, and environmental benefits related to the disposal of waste materials and to reduced carbon dioxide emissions. Reactivity of RHA is attributed to its high content of amorphous silica, and to its very large surface area governed by the porous structure of the particles [1,2]. Generally, reactivity is favored also by increasing fineness of the pozzolanic material. However, Mehta [1] has argued that grinding of RHA to a high degree of fineness should be avoided, since it derives its pozzolanic activity mainly from the internal surface area of the particles. ProductionRice is the seed of the monocot plants Oryza sativa or Oryzaglaberrima. As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East and South Asia, the Middle East, Latin America, and the West Indies. It is the grain with the second-highest worldwide production, after corn.

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“…Therefore, SiC nanowires have a great potential to be used as reinforcing element in ceramic, metal and polymer-matrix composites. There are several routes to synthesize SiC nanowires, such as chemical vapor deposition, through reaction of silica and carbon solid mixtures, by reduction of methyl trichlorosilane, by reaction of Si 3 N 4 with carbon, and by thermal decomposition of rice husk [27][28][29][30]. It can be concluded that the porous bodies can provide enough growth space for nanowires [31,32].…”

Section: Introductionmentioning

confidence: 99%