チタン酸ストロンチウムバリウム粒子分散系のエレクトロレオロジー効果と粒子表面状態の関係

概要

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Electrorheological response of barium strontium titanate (BST)/silicone oil suspension was experimentally studied with measurements of generated shear stress in a range of field frequency (200-4000 Hz) under steady shear. The BST particles were synthesized by the hydrolysis of complex alkoxide precursor that was prepared in a reflux of metallic barium, metallic and tetraethylorthotitanate in solvent. The hydrolysis was performed by the addition of water/ethanol solution to the precursor solution. Generated shear stress of as-prepared (unannealed) BST particles system decreased with an increase in frequency, while that for 1100 °C-annealed BST system increased with frequency. XPS measurements revealed that alkoxyl groups that were derived from unreacted alkoxide were on surface of the as-prepared BST particles, and the annealing at 1100 °C decomposed the alkoxyl groups to hydroxyl groups. Difference in electric conductivities of the surfaces is considered to be responsible for the different shear stress behaviors of the as-prepared and annealed particles.
日本レオロジー学会の論文