KJ Ceramics 31

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Detailed Program

Paper Number : EL-I03

Time Frame : 17:20~17:45

Presentation Date : Thurseday, 27, November

Session Name : Electronic Ceramics

Session Chair 1# : Chae Il Cheon

Session Chair 2# : Hitoshi Ohsato

Investigation of the interaction between the dispersant molecule and the surface of BaCO3 particle

Koichiro TSUZUKU

Gunma University

Introduction
Electro-ceramics synthesized with various methods. Solid-state reaction method is applying widely to not only electro-ceramics but also other fine-ceramics. In the case of preparation of electro-ceramics such as BaTiO3 by solid-state reaction method, quality of resultant products is affected by size of raw materials, homogeneity of dispersion, condition of synthesis process, etc. For example of synthesis of 100nm BaTiO3 by solid-state reaction, several nm BaCO3 and TiO2 should be dispersed and mixed with uniformly. Normally small size particle are generally formed agglomeration because its higher surface energy. Dispersant such as poly-carboxylic acid is being used to disperse fine raw materials powder. Agglomeration of particles was prevented by electro-chemically and/or physically effects by adsorption of dispersant molecules at surface of each particle. The surface condition of different kind of particles is not same and resultant adsorption condition is also not same. Therefore choice of appropriate dispersant is one of important point to synthesize homogeneous products. However, adsorption state of dispersant molecules at surface of certain particles produced by different manufacturer was not enough investigated.
Result and discussion.
Seven kinds of different BaCO3 powder (reagent: R, four products of company S: S-1, S-2, S-3, S-4, two products of company N: N-1, N-2) were used. Ammonium citrate: AC was used as dispersant. Sample slurry was prepared by conventional wet mixing process. Clear parts obtained from centrifuged slurry were analyzed with 300MHz 1H-NMR spectrometer. The interaction between the dispersant molecule and the surface of particle has been estimated from the width of split of -CH2 quartet peak on 1H-NMR spectra.
Spin coupling constant: J and chemical shift: Δδ calculated from obtained spectra were shown in Fig. 1. J-values obtained from different BaCO3 products were almost same, however Δδ were different. This result is probably indicating that different BaCO3 products have different surface properties. Furthermore, SSA of the samples S-4 and N-2 were almost same, but Δδ of N-2 was larger than S-4. Interaction at the surface of N-2 powder seems to be stronger than that of S-4.

Figure 1 J-values and Δδ calculated from 1H-NMR spectra.

Acknowledgements :

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