Low-temperature Magnesiothermic Synthesis of Mesoporous Silicon Carbide from an MCM-48/Polyacrylamide Nanocomposite Precursor

Available online at SciVerse ScienceDirect

J. Mater. Sci. Technol., 2013, -(-), 1e6

Low-temperature Magnesiothermic Synthesis of Mesoporous Silicon Carbide

from an MCM-48/Polyacrylamide Nanocomposite Precursor

Zahra Saeedifar1)*, Amir Abbas Nourbakhsh2), Roozbeh Javad Kalbasi2), Ebrahim Karamian1)

1) Department of Materials Engineering, Najafabad Branch, Islamic Azad University, P.O. Box 517, Isfahan, Iran2) Department of Materials Engineering, Shahreza Branch, Islamic Azad University, Isfahan, Iran

[Manuscript received October 23, 2012, in revised form December 14, 2012]

* Corressaeedifar1005-03JournalLimited.http://dx

Please c

Mesoporous silicon carbide with high specific surface area was successfully synthesized from an MCM-48/polyacrylamide nanocomposite precursor in the temperature range of 550e600 �C (below the melting point ofMg) by means of a magnesiothermic reduction process. The MCM-48/polyacrylamide precursornanocomposite was prepared by in-situ polymerization of acrylamide monomer in the presence of mesoporousMCM-48 synthesized by sol-gel method. The physicochemical properties and microstructures of thenanocomposite precursor and the low-temperature SiC product were characterized by X-ray diffraction (XRD),differential scanning calorimetry-thermo gravimetric analysis (DSC-TGA), transmission electron microscopy(TEM) and N2 adsorptionedesorption. TEM micrographs and BrunauereEmmetteTeller (BET) gas adsorptionstudies showed that the SiC powder was nanocrystalline and had a specific surface area of 330 m2/g anda mesoporosity in the range of 2e10 nm. The presence of an exothermic peak in the DSC trace correspondsto the self-combustion process of the SiC magnesiothermic synthesis. The results also show that the carbonin excess to that required to produce SiC plays a role in the reduction of the SiO2. The mechanism ofmagnesiothermic synthesis of mesoporous SiC is discussed.

KEY WORDS: Silicon carbide; Nanocomposite; Mesoporous; Magnesiothermic reduction; In-situ polymerization

1. Introduction

The high thermal conductivity, oxidation resistance, mechan-ical strength and chemical inertness of silicon carbide make itsuitable for a variety of applications as a biomaterial, in semiconductive devices for high temperature use and as a light-weight/high strength catalyst[1,2]. If it can be prepared with anaverage surface area of 20e100 m2/g and appropriate pore sizedistribution, it would be an excellent candidate for heteroge-neous catalysis. Thus, in recent years research on the synthesis ofSiC with a high specific surface area has been of high priority.An ordered mesoporous silicate with large pores (2e50 nm),high volume and surface area and a narrow pore size distributionwould be an ideal precursor for porous SiC with a high specificsurface area[1,3,4]. MCM-48 is a mesoporous silica with theadvantage of cubically-ordered pores and a three-dimensionalstructure providing inner surfaces with improved exposure toguest molecules and less pore faces to be clogged[3,5].

ponding author. Tel.: þ98 9132084405; E-mail address: [email protected] (Z. Saeedifar).02/$e see front matter Copyright� 2013, The editorial office ofof Materials Science & Technology. Published by ElsevierAll rights reserved..doi.org/10.1016/j.jmst.2013.01.007

ite this article in press as: Z. Saeedifar, et al., Journal of Materials Scie

Currently, several different methods are used for the synthesisof mesoporous SiC from mesoporous precursors. These includedirect reaction of silicon with mesoporous carbon at>1200 �C[6,7], penetration of preceramic polymers (e.g. poly-carbosilanes) into mesoporous SiO2 followed by pyrolysis at1000e1400 �C[8], and carbothermal reduction of mesoporousSiO2 at about 1400 �C[9,10]. Because of problems associated withprecise control of grain growth and sintering of the product SiCit is difficult to produce porous SiC structures at high tempera-tures and the production of fully ordered mesoporous SiCstructures has not yet been fully achieved[11].Another method for synthesizing mesoporous SiC is the low-

temperature direct conversion of SiO2/C nanocomposite struc-tures into related SiC materials without destroying their struc-tural morphology. This low-temperature reaction can be achievedby magnesiothermic reduction by using Mg[11,12]. Shi et al.demonstrated the magnesiothermic reduction method for nano-structured SiC materials using a SiO2/carbon nanocomposite asthe precursor and Mg as the reducing agent at 600e900 �C[12].Zhao et al. synthesized mesoporous SiC by magnesiothermicreduction of a sacharose/SBA-15 composite at 650 �C[11].Polymer/mesoporous silica nanocomposite precursors can be

prepared by several methods, including sol-gel processing,blending and in-situ polymerization. In-situ polymerization inthe presence of a mesoporous matrix is an appropriate method

nce & Technology (2013), http://dx.doi.org/10.1016/j.jmst.2013.01.007

mailto:[email protected]

mailto:[email protected]

http://dx.doi.org/10.1016/j.jmst.2013.01.007

www.sciencedirect.com/science/journal/10050302

Fig. 1 X-ray diffraction pattern in low angles of MCM-48 (a),polyacrylamide/MCM-48 nanocomposite (b).

2 Z. Saeedifar et al.: J. Mater. Sci. Technol., 2013, -(-), 1e6

for increasing the contact surface between the mesoporousmatrix and carbon, and the resulting uniform distribution ofcarbon and silica retains porous structure of the resultingSiC[13,14]. Kalbasi and Mosadegh[15] prepared poly(4-vinylpyridine)/MCM-48 nanocomposites by in-situ polymeriza-tion of 4-vinylpyridine monomers inside the pores of MCM-48silica.In the present study we utilize magnesiothermic reduction to

synthesize mesoporous SiC from a precursor nanocomposite ofMCM-48 with polyacrylamide at 550e600 �C (below themelting point of Mg). The MCM-48/polyacrylamide precursornanocomposite was prepared by in-situ polymerization ofacrylamide monomer in the presence of mesoporous MCM-48synthesized by sol-gel method. The mechanism of mesoporousSiC synthesis is also discussed.

2. Experimental

Mesoporous MCM-48 was synthesized by dissolving 2.4 ghexadecyltrimethylammonium bromide in 50 ml deionized waterand adding 50 ml ethanol and 12 ml 32 wt% ammonia. Aftermixing for 10 min, 3.4 g tetraethyl orthosilicate (TEOS) wasadded and mixed for 2 h at room temperature. The resulted solidproduct was filtered, washed with deionized water, dried atambient temperature and calcined at 550 �C for about 5 h.This mesoporous MCM-48 product was used to prepare the

MCM-48 /polyacrylamide nanocomposite by mixing 0.5 g ofMCM-48 with 0.3944 g acrylamide monomer, 12 ml tetrahy-drofuran and 0.0403 g of 3 mol% benzoyl peroxide in a round-bottom flask. The mixture was refluxed at 65e70 �C for 5 h andthe resulted MCM-48/polyacrylamide nanocomposite wasfiltered, washed with tetrahydrofuran and dried at roomtemperature.Mesoporous SiC was then prepared from this MCM-48/

polyacrylamide nanocomposite precursor by carbonizing in anAr atmosphere at 700 �C at a heating rate of 5 �C/min anda holding time of 3 h. The resulted MCM-48/C nanocompositewas mixed with Mg powder in the molar ratio (SiO2:Mg ¼ 1:2)and heated in Ar at 550e600 �C at a heating rate of 5 �C/min anda soaking time of 6 h to synthesize mesoporous b-SiC. Theproduct powder was freed from unwanted impurities by room-temperature acid treatment in a mixture of 10 wt% HF and4 mol/l HNO3 for 5 h, filtered, washed with distilled water anddried at room temperature.The nanocomposite precursor and low-temperature SiC

product were characterized by X-ray diffraction (XRD, PhilipsPW3040, copper radiation, wavelength 0.15406 nm, nickelfilter), transmission electron microscopy (TEM, Zeiss EM10C,Germany), N2 adsorptionedesorption (BEL InceBelsorp,Japan), differential scanning salorimetry (DSC, DSC-302, Bähr-Thermoanalyse GmbH, Hüllhorst Germany), and thermogravi-metric analysis (TGA, Kimia Sanaat Ara, TG10).

3. Results and Discussion

Fig. 2 N2 adsorptionedesorption isotherm of mesoporous MCM-48.

3.1. Characterization of MCM-48 and MCM-48/polyacrylamidenanocomposite precursors

Fig. 1(a) shows the low-angle XRD pattern of mesoporousMCM-48 after calcination. The diffraction pattern from MCM-48 contains reflections from the 211 and 220 planes in theangular range w2q ¼ 3� and a broad feature from the 332 plane

Please cite this article in press as: Z. Saeedifar, et al., Journal of Materials Scie

at w2q ¼ 5�. The presence of a separate diffraction peak at2q ¼ 3.5� indicates a highly ordered type of mesoporous MCM-48; thus, the XRD pattern includes peaks associated with thespace group Ia3d and an ordered cubic structure[16e18].Fig. 1(b) shows the low-angle XRD pattern of MCM-48/

polyacrylamide nanocomposite, containing a strong (211)diffraction peak at w2q ¼ 3�, indicating that the polymerizationof acrylamide in the presence of the MCM-48 has not signifi-cantly degraded the porous structure. Decreased intensities of theMCM-48/polyacrylamide nanocomposite peaks indicatea decrease in the order of the guest MCM-48 structure[15,17].According to Bragg’s law, the d-space of (211) plane increasedby addition polyacrylamide to MCM-48, therefore the peakposition moved to lower angle.Fig. 2 shows the N2 adsorptionedesorption isotherm of the

mesoporous MCM-48. According to the IUPAC nomenclature,the sample displays a typical type IV isotherm with steep risesdue to capillary condensation, which is characteristic of themesoporous materials[19e21]. Table 1 shows the BET porosityresults of the MCM-48 precursor. The specific BET surface areaof the MCM-48 sample is 1237 m2/g.

3.2. Characterization of carbonized polyacrylamide/MCM-48nanocomposite and Mg reaction mixture

DSC-TGA curves of the carbonized polyacrylamide/MCM-48nanocomposite and Mg (Fig. 3) show an exothermic peak at590 �C (below the melting point of Mg at 650 �C) resulting fromthe reduction of the silica by Mg[22]. This is the temperaturerange at which chemical reaction in the starting mixture and


Table 1 BET data for MCM-48 precursor

BET surface area,aS,BET (m2 g�1)

Total pore volume (p/p0¼0.99)(cm3 g�1)

Mean porediameter (nm)

1237 0.6764 2.1855

Z. Saeedifar et al.: J. Mater. Sci. Technol., 2013, -(-), 1e6 3

formation of b-SiC begin. The TGA curves show a mass loss ofabout 2% at <150 �C due to moisture release, and a mass gain ofabout 5% at 150e300 �C related to the facile adsorption of theAr carrier gas resulted from the high specific surface area of thecarbonized MCM-48/polyacrylamide. At 300e450 �C all poresin the sample are filled with Ar and the rate of weight increasewill be closed to zero. In addition, at 450e600 �C there is a massloss due to fragmentation of the mesoporous structure and theinitiation of the reduction reaction. Therefore, in addition to masschanges due to the fragmentation of the structure and the releaseof Ar, Mg sublimation also contributes to a mass loss in thistemperature range. In this case, reduction by the Mg is a solid-gas reaction that proceeds much more rapidly than a solid-solid reaction[22] facilitating the low-temperature formation ofb-SiC. In addition, due to high specific surface of precursor andthe Mg rapid penetration, silica could be reduced by mostmagnesium gas and the removal of gaseous magnesium mayresult in a few mass losses (300e450 �C). When reaction (1) isalmost completed, and Mg sublimation is also occurring, morethan the stoichiometric amount of Mg is required[11,12,23,24].

SiO2ðsÞ þ CðsÞ þ 2MgðsÞ ¼ SiCðsÞ þ 2MgOðsÞ (1)

However, XRD results (Fig. 4) show that when the stoichio-metric amount of Mg is used, no SiO2 remains and completeoxidation occurs, but Mg2Si is formed, suggesting the presenceof extra Mg[25]. However, although the amount of carbon in thesystem is based on stoichiometry, the presence of Si in thesample with the molar ratio C:SiO2:Mg ¼ 1:1:2 suggestsa carbon deficiency due to the formation of CO[24]. Thus, it ispossible that both Mg and C are acting as reducing agents forSiO2 reduction. The likelihood of carbon participation inreduction with the formation of CO would also explain the 10%weight loss in the samples (C:SiO2:Mg ¼ 1:1:2, 2:1:2, 2.5:1:2)after heat treatment at 550e600 �C for 6 h and the misidentifi-cation of carbon in X-ray diffraction pattern, since SiO2 reduc-tion by Mg should not produce a mass change[22].

Fig. 3 DSC-TG curves of carbonized polyacrylamide/MCM-48 nano-composite and Mg with molar ratio C:SiO2:Mg ¼ 2:1:2, heatingrate 5 �C/min up to 600 �C then held at this temperature for30 min in Ar.


3.3. Characterization of mesoporous SiC

Fig. 4 shows X-ray diffraction patterns of the carbonizedmixtures of polyacrylamide/MCM-48 nanocomposite with Mgin the molar ratios C:SiO2:Mg ¼ 1:1:2, 2:1:2, 2.5:1:2 heated at550e600 �C for 6 h. Each of the samples of the three molarcompositions before acid etching (Fig. 4(a)) contains b-SiC. Asthe carbon content is increased, the contact distance between theSiO2 and Mg is increased by dilution with the carbon in themixture, and therefore causes a decrease of the diffraction peakintensity of the b-SiC product. However, when the carboncontent was increased, some exceeding carbon would remain inthe final product, which could also make the intensity of the SiCdiffraction peaks decrease. The XRD pattern peak of the sampleof molar ratio 1:1:2 contains Si and Mg2Si peaks of approxi-mately similar intensity. These reflections, together the gradualdisappearance of reflection from Mg2SiO4 in samples of higherC:SiO2 molar ratio, support the evidence of the DSC-TGAresults that the carbon not only forms SiC but also is partici-pating in the reduction of the SiO2. The elimination of the Mg2Siphase while increasing the C:SiO2 molar ratio could be due tothe absence of residual Si in samples because of its reaction withthe additional carbon. Meanwhile, increasing the C:SiO2 molarratio would decrease the intervention of carbon in the silicareduction due to the weakening of magensiothermic self-combustion processes (lower access of magnesium to silica).The XRD patterns of the acid-leached samples (Fig. 4(b))contain only the (111), (220) and (311) reflections of cubic b-SiCand no evidence of Mg2Si, Mg2SiO4 or carbon.Fig. 5(a) and (b) present TEM images of mesoporous SiC in

the temperature range 550e600 �C showing SiC particles ofabout 230 nm in diameter. The crystallite size of synthesized SiCwas calculated by Williamson-Hall relation[26] which is shown inEq. (2).

bhklcos qhkl ¼ ½kl=t� þ 4εsin qhkl (2)

where t ¼ crystallite size, k ¼ 0.9 is a correction factor toaccount for particle shapes, bhkl ¼ full width at half maximumof the peaks ((111), (220), (311)) in the XRD pattern,l ¼ wavelength of Cu target (0.15405 nm), qhkl ¼ Braggangle is related to (hkl) plane and ε ¼ lattice strain. Plottingthe value of bhkl cosqhkl as a function of 4sin qhkl thecrystallite size may be estimated from the intersection with thevertical axis[26].Analysis of XRD patterns by Williamson-Hall relation[26] and

TEM image (Fig. 5(b)) indicates that the average size of the SiCcrystallites is approximately 20 nm. Although the SiC producthas the same structure as the mesoporous MCM-48 template, it isless ordered than the silica template, possibly due to fragmen-tation of the latter during the synthesis reaction[11].Fig. 6(a) and (b) show the N2 adsorptionedesorption isotherm

and BET plot of the SiC sample. The N2 adsorptionedesorptionisotherm is of type-IV curve shape confirming its mesoporousnature and the type-H3 hysteresis loop does not exhibit anylimiting adsorption at high values of p/p0 typical of aggregates ofplate-like particles giving rise to slit-shaped pores[27,28]. Table 2shows the BET data for the SiC sample, which has a specificBET surface area of about 330 m2/g.Fig. 7 shows the pore size distribution of SiC derived from (a)

a BarreteJoynereHalenda (BJH) plot and (b) an Micropore(MP) plot. The pore size distributions determined by both BJHand MP analysis indicates that the SiC has very narrow size


Fig. 4 X-ray diffraction pattern of mesoporous b-SiC synthesized at 550e600 �C: (a) before acid etching, (b) after acid etching.

Fig. 5 TEM images of synthesized mesoporous SiC in temperature range 550e600 �C (a) 63000 �, (b) 100000 �.


distribution of about 2 nm. Table 3 shows the results of the BJHplot and MP plot for the SiC sample.

3.4. Suggested mechanism of SiC synthesis by magnesiothermicreduction

Possible chemical reactions between SiO2, Mg and C in themagnesiothermic synthesis mixture are shown in Eqs. (3)e(9)below[23,24].

SiO2ðsÞ þ 2MgðsÞ ¼ SiðsÞ þ 2MgOðsÞ (3)

Fig. 6 (a) N2 adsorptionedesorption iso


SiðlÞ þ CðsÞ ¼ SiCðsÞ (4)

SiO2ðsÞ þ CðsÞ ¼ SiOðgÞ þ COðgÞ (5)

SiOðgÞ þ 2CðsÞ ¼ SiCðsÞ þ COðgÞ (6)

2MgOðsÞ þ SiO2ðlÞ ¼ Mg2SiO4ðsÞ (7)

therm of SiC, (b) BET plot of SiC.


Table 2 BET data for SiC

BET constant (C) Volume of gas absorbedin monolayer

Vm (cm3 (STP) g�1)

BET surfacearea aS,BET (m2 g�1)

Total porevolume (p/p0 ¼ 0.99)

(cm3 g�1)

Mean porediameter (nm)

289.36 76.116 331.29 0.4809 5. 8058

Fig. 7 Pore size distribution of SiC derived from the BJH plot (a) and the MP plot (b).

Table 3 Results of the BJH and MP analysis of SiC

BJH plot MP plot

BJH > 2 nm adsorption BJH > 2 nm desorption MP ¼ 0.42e2 nm

Mesopore area(m2 g�1)

Mesoporevolume

(cm3 g�1)


Mesoporevolume

(cm3 g�1)


Micropore area(m2 g�1)

Total surface area(m2 g�1)

Microporevolume

(cm3 g�1)

209.37 0.4150 164.73 0.3819 151.89 206.96 353.85 0.1296

Z. Saeedifar et al.: J. Mater. Sci. Technol., 2013, -(-), 1e6 5

2MgðgÞ þ SiðsÞ ¼ Mg2SiðsÞ (8)

The overall chemical reaction is then:

SiO2ðsÞ þ CðsÞ þ 2MgðsÞ ¼ SiCðsÞ þ 2MgOðsÞ (9)

According to the DSC-TGA curves the Mg powder sublimesat 450 �C. The C and SiO2 are surrounded by Mg. However,because the Gibbs free energy of reaction (3) is less than that ofthe other reactions, the SiO2 will be reduced preferentially, withthe exothermic formation of MgO. The resulting release of heatwill melt Si which then coats the C in the system by capillaryaction. Following the rapid penetration of C by Si, a solid-liquidreaction occurs between these two reactants, forming SiCaccording to Eq. (4). Thus, MgO and SiC will be formedsimultaneously[23,24]. The presence of Mg2SiO4 in the reactionproducts suggests incomplete reaction during the rapidcombustion processes[23], while the formation of Mg2Si is sug-gested to result from the presence of a significant excess of Mgin the reaction mixture[25].The initiation temperature of the reaction is expected to be

affected by the particle size of the Mg reducing agent, smaller Mgparticle sizes initiating the reaction below the melting point of theMg, because its vapor pressure increases with smaller Mg particlesizes. The amount of carbon in the system also influences the


initiation temperature of the reaction; the C acts as a filler materialand with increasing C content, the contact distance between theSiO2 and Mg is increased by dilution, increasing the initiationtemperature of the reaction[29]. These mechanistic deductions arefully consistent with the XRD results.

4. Conclusion

Mesoporous SiC with high specific surface area (330 m2/g) wassynthesized by magnesiothermic reduction from MCM-48/polyacrylamide nanocomposite precursors at 550e600 �C(below the melting point of Mg). The MCM-48/polyacrylamideprecursor nanocomposite was prepared by in-situ polymerizationof acrylamide monomer in the presence of mesoporous MCM-48.A 10% reduction in sample weight after heat treatment determinedby DSC-TGA and the presence of an unwanted Mg2Si phaseshown by XRD suggested that both C (from the decomposition ofthe polymer) andMg were acting as reducing agents. XRD resultsfor samples of differing C content indicated that the increase in Ccontent increased the separation distance between Mg and SiO2

particles by a dilution effect, and therefore decreased the diffrac-tion peak intensity of the b-SiC product. TEM images showed thatthe resulted SiC possesses a structure similar to its mesoporousMCM-48 precursor and N2 adsorptionedesorption isothermsconfirmed its mesoporosity. The lowering of the synthesistemperature by using magnesiothermic reduction was an impor-tant factor in securing a mesoporous SiC structure.



REFERENCES

[1] J. Parmentier, J. Patarin, J. Dentzer, C.V. Guterl, Ceram. Int. 28(2002) 1e7.

[2] G. Zheng, X. Yin, J. Wang, M. Guo, X. Wang, J. Mater. Sci.Technol. 28 (2012) 745e750.

[3] J.C. Vartuli, W.J. Roth, J.S. Beck, S.B. McCullen, C.T. Kresge, MolSieves 1 (1998) 97e119.

[4] I. Vida-Simiti, N. Jumate, V. Moldovan, G. Thalmaier, N. Sechel, J.Mater. Sci. Technol. 28 (2012) 362e366.

[5] R. Köhn, M. Fröba, Catal. Today 68 (2001) 227e236.[6] Z. Liu, W. Shen, W. Bu, H. Chen, Z. Hua, L. Zhang, L. Li, J. Shi,

S. Tan, Micropor. Mesopor. Mater. 82 (2005) 137e145.[7] Y. Shi, Y. Wan, D. Zhao, Chem. Soc. Rev. 40 (2011) 3854e3878.[8] Y.F. Shi, Y. Meng, D.H. Chen, S.J. Cheng, P. Chen, T.F. Yang, Y.

Wan, D.Y. Zhao, Adv. Funct. Mater. 16 (2006) 561e567.[9] G.Q. Jin, X.Y. Guo, Micropor. Mesopor. Mater. 60 (2003) 207e212.[10] Z.X. Yang, Y.D. Xia, R. Mokaya, Chem. Mater. 16 (2004) 3877e

3884.[11] B. Zhao, H. Zhang, H. Tao, Z. Tan, Z. Jiao, M. Wu, Mater. Lett. 65

(2011) 1552e1555.[12] Y. Shi, F. Zhang, Y.S. Hu, X. Sun, Y. Zhang, H.I. Lee, L.D. Chen,

G. Stucky, J. Amer. Chem. 132 (2010) 5552e5553.[13] P. Gómez-Romero, C. Sanchez, Functional Hybrid Materials,

Wiley-VCH, Weinheim, 2003, pp. 86e121.[14] L. Wei, N. Hu, Y. Zhang, Materials 3 (2010) 4066e4079.


[15] R.J. Kalbasi, N. Mosaddegh, Catal. Commun. 12 (2011) 1231e1237.[16] S.E. Dapurkar, S.K. Badamali, P. Selvam, Catal. Today 68 (2001)

63e68.[17] A.M. Doyle, E. Ahmed, B.K. Hodnett, Catal. Today 116 (2006)

50e55.[18] K. Wang, Y. Lin, M.A. Morris, J.D. Holmes, J. Mater. Chem. 16

(2006) 4051e4057.[19] R.J. Kalbasi, N. Mosaddegh, A. Abbaspourrad, Appl. Catal. 423

(2012) 78e90.[20] X. Luo, Zh. Wang, L. Chen, X. Wang, B. Wu, Catal. Lett. 132

(2009) 450e453.[21] K. Schumacher, M. Grun, K.K. Unger, Micropor. Mesopor. Mater.

27 (1999) 201e206.[22] H.D. Banerjee, S. Sen, Mater. Sci. Eng. 52 (1982) 173e179.[23] R. Gerhardt, Properties and Applications of Silicon Carbide,

InTech, 2011, pp. 411e425.[24] S. Niyomwas, J. Metal. Mater. Min. 19 (2009) 21e25.[25] W. Chen, Z. Fan, A. Dhanabalan, C. Chen, C. Wang, J. Electro-

chem. Soc. 158 (2011) 1055e1059.[26] V. Biju, N. Sugathan, V. Vrinda, S.L. Salini, J. Mater. Sci. 43 (2008)

1175e1179.[27] K. Kaneko, J. Memb. Sci. 96 (1994) 59e89.[28] K.S.W. Sing, D.H. Everett, R. Haul, L. Moscou, R.A. Pierotti, J.

Rouquerol, T. Siemieniewska, Pure Appl. Chem. 54 (1982)2201e2218.

[29] R.A. Cutler, K.M. Rigtrup, J. Am. Ceram. Soc. 75 (1992) 36e43.


Documents

Low-temperature Magnesiothermic Synthesis of Mesoporous Silicon Carbide from an MCM-48/Polyacrylamide Nanocomposite Precursor