Photonic crystals in biology - NanoTR-VI

PPoster Session, Thursday, June 17Theme F686 - N1123Alternative Method to Production of Nano-Sized -SiAlON Powders111Onur EserP P, USemra KuramaUP P* and Göktug GünkayaP1PDepartment of Materials Science and Engineering, Anadolu University, Eskisehir, TurkeyAbstract-In this study, the optimum milling system was investigated by using sedimentation method. The effect of type of mediums anddispersants were researched by using sedimentation tests. After the optimization of milling medium wet milling system was used to decreasingparticle size of starting powders. All the milling time results were discussed related with the particle size of milled powder.There are some routes to prepare nano-sized SiAlONpowders such as plasma-chemical and laser synthesis [1], solgeland as a top-to-bottom process high-energy mechanicalmilling [2]. Although, this method promises very low particlesizes (~40 nm), would increase the cost of the initial powder[3]. In this study -SiAlON described as SiR4RAlR2ROR2RNR6R, anddoped with 5 wt.% YR2ROR3R. The weighed powders wereplanetary ball milled (Pulverisette 6 Fritsch, Germany) withSiR3RNR4R balls for 2 h in different solvent compositions (toluene,methyl ethyl keton, ethanol) and in different ratios. Thesolvent ratios were determined as given in the literature [4].The level of agglomeration, a critical parameter for theefficiency of the milling process, was determined using thesedimentation method. As explained in our previous study [5],the most dispersed solvent composition was determined for-SiAlON system in three kinds of dispersant (oleic acid,polyethyleneglicol, sodium tripolyphosphate). In the presentstudy polyvinylpyrrolidon was also investigated as analternative to the other three in the -SiAlON system. Theoptimum solvent ratio was investigated in an ethanol:toluenesystem of 70:30 vol. ratio with the highest sedimentationheight. The effect of the dispersant in the selected solventcomposition was investigated by addition of oleicacid, STPP(sodium tripolyphosphate), PEG (polyethyleneglicol) and PVP(polyvinylpyrrolidon) as dispersants (Figure 1).Sediment height (mm)130125120115110105100950 0.5 1 1.5 2 2.5 3PVP(wt. %)Time (h)Figure 1. Effect of amount of (a) PVP on sedimentation heightAccording to the result, the binary solvent system of ethanoland toluene (at a volume ratio 70:30) with 3 wt.% addition ofPVP shows the most dispersed behavior and is used as amilling medium for milling studies. The first powder producedby conventional method which has a powder:ball:alcohol ratioof 1:1.5:2 and the other powder produced by high-energymechanical milling in wet medium at 450 rpm for differenttimes up to 40 hours. For the characterization of the particlesize of the milled powders, two different types of method wereused in this study. One of these is the dynamic light scatteringmethod, and the average particle size of the milled powders isgiven in Fig. 2-3.The second method, BET, was used tomeasure the surface area of the powders an the mean particlesize of (DRBETR). Comparison of the results of both methodsshows that even though the particle size of powders decrease0.51.02.52.01.53.0by increasing milling time, from sample C to N50. There wasobserved differences in results. These differences can beexplained by the formation of agglomerates which are difficultto deform, even using ultrasonic treatment in the dynamic lightscattering method. However, in the BET method the diffusionof NR2R gas into agglomerates is possible, giving more realisticresults than the dynamic light scattering method.Particle Size (nm)7006005004003002001000Conventional51020Time (h)Figure 2. Particle size analyse of powder by dynamic light scatteringmethodParticle Size (nm)250200150100500Conventional51020Time (h)Figure 3. Particle size analyse of powder by BETAs a consequence, the high energy milling in a wet mediumsystem is an effective way to produce nano- -SiAlONstarting powders. The most efficient milling medium for the-SiAlON suspensions is investigated as 70 vol. % Ethanol-30vol. % Toluen with the addition of 3 wt% PVP. The minimum-SiAlON powder size was obtained as 92 nm after 50 hmilling in this medium.This work was supported by TUBITAK under Grant No.108T661.*Corresponding author: skurama@anadolu.edu.tr[1]. Bulic, F., Zalite, I., Zhilinska, N., 2004. Comparison of plasma-chemicalsynthesised SiAlON nano-powder and conventional prepared SiAlONpowder, Journal of the European Ceramic Society, 24: 3303-3306.[2]. Li, Q., Zhang, C., Komeya, K., Tatami, J., Meguro, T., Gao, L., 2003.Nano powders of -SiAlON carbothermally produced via a sol-gel process,Journal of Materials Science Letters, 22: 885-887.[3]. Xu, X., Nishimura, T., Hirosaki, N., Xie, R., Yamamoto, Y., Tanaka, H.,2005. Fabrication of -SiAlON nanoceramics by high-energy mechanicalmilling and spark plasma sintering, Nanotechnology, 16 : 1569-1573.[4] Eser, O. and Kurama, S., (2010). The effect of the wet-milling process onsintering temperature and the amount of additive of SiAlON ceramics,Ceramics International, doi:10.1016/j.ceramint.2009.12.025.[5] Eser, O., Kurama, S. and Gunkaya, G., 2010. The production of -SiAlON ceramics with low amount of additive, at low sintering temperature,J. The European ceram. Soc,. doi: 10.1016/j.jeurceramsoc.2010.01.024.3030404050506th Nanoscience and Nanotechnology Conference, zmir, 2010 655