Study on Electrorheological Fluids Dispersing Ferroelectrics in the Range of Size Dependence

* BaTiO_3和Ba_ Sr_TiO_3细粉的电流变效应与加热温度的关系水热合成<0.8>了粒径为0.1 μ m的<0.2>BaTiO_3和Ba_Sr_TiO_3的原始细粉<0.8><0.2>。将粉末在一定温度下加热以使其以10%的体积比完全分散在硅油中。用双圆筒流变仪测定了分散油的电流变性。人们注意到一个有趣的结果，电流效应--通过施加直流电场（在这种情况下为2 kV/mm）增加剪切应力--对于在特定温度下加热的粉末来说出现了奇异峰。BaTiO_3和Ba_ Sr_ TiO_3的温度分别<0.8><0.2>为700 ℃和900 ℃。X射线衍射表明，这两种粉末的200个峰正好在铁电体特有的200/002分裂之前。钛酸钡的胶体化学及表面处理钛酸钡的电流变性能钛酸钡分散在乙醇中的zeta电位为40 mV，十二烷基硫酸钠的吸附使其zeta电位降至16 mV，α-烯烃磺酸钠的吸附使其zeta电位降至-。分散油的表观粘度为未处理BaTiO_3的1/5。然而，ER效应也减少了一半。

* Electrorhelogical Effects as Functions of Heating Temperatures of Fine Powders of Barium Titanate and Ba_<0.8>Sr_<0.2>TiO_3The raw fine powders of BaTiO_3 and Ba_<0.8>Sr_<0.2>TiO_3 were hydrothermally synthesized with particle sizes of 0.1mum. The powders were heated at temperatures to thoroughly disperse in silicon oil with a volume ratio of 10%. Electrorheologies of dispersed oils were measured by using a double cylinder rheometer. An interesting result was noted that electrorhelogical effects -the increase in shear stress by applying a dc electric field, 2 kV/mm in this case - took singular peaks for powders heated at specific temperatures. The respective those temperatures for BaTiO_3 and Ba_<0.8>Sr_<0.2>TiO_3 were 700ﾟC and 900ﾟC.The X-ray diffractions revealed that the 200 peaks of those powers were just before 200/002 splittings which were characteristic to ferroelectrics.* Colloid Chemistry of Barium Titanate and Electrorheology of Surface Treated Barium TitanateThe zeta -potential of BaTiO_3 dispersed in ethanol was 40 mV.The adsorption of sodium dodecyl sulfate decreased the potential to 16 mV,and sodium alpha-olefin sulfonate decreased it down to minus.BaTiO_3 were mixed with toluene containing poly-buthyl metacrylate. The apparent viscosity of the dispersed oil was 1/5 of that containing non-treated BaTiO_3. However, the ER effect also decreased in half.