Abstract

A comparative analysis has been made for the dielectric and electrorheological properties of suspensions of highly dispersed powders of bismuth ferrites BiFeO₃ and Bi₂Fe₄O₉ in polydimethylsiloxane PMS-300. Dielectric characteristics (dielectric constant, dielectric loss tangent) for the suspensions in frequency range 2.5–10⁶ Hz have been determined and non-Debye character of relaxation processes in these systems has been revealed. The measured values of dielectric constant for the disperse bismuth ferrites at zero and infinite frequency (ε₀ and ε_∞) are 150 and 59 for BiFeO₃, 22 000 and 14 for Bi₂Fe₄O₉, respectively. Electrorheological properties of bismuth ferrite suspensions in static electric field (up to 5 kV) in tension, compression, and shear modes have been analyzed. It has been found that the values of electrorheological effect for BiFeO₃ suspensions in polydimethylsiloxane PMS-300 are small even at high concentrations of disperse phase (60 wt %). On the contrary, the suspensions of highly disperse Bi₂Fe₄O₉ exhibit distinct electrorheological effect. For 80 wt % Bi₂Fe₄O₉ suspension, the tensile yield point reached ~7 kPa in electric field of 5 kV, while compressive stress was 12 kPa.

中文翻译：

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基于铋铁氧体BiFeO 3和Bi 2 Fe 4 O 9的电流变流体

摘要

已对聚二甲基硅氧烷PMS-300中高分散性铋铁氧体BiFeO ₃和Bi ₂ Fe ₄ O ₉的悬浮液的介电和电流变特性进行了比较分析。已经确定了频率范围为2.5–10 ⁶ Hz的悬浮液的介电特性（介电常数，介电损耗正切），并且揭示了这些系统中弛豫过程的非德拜特性。在零和用于分散铋铁氧体介电常数的测量值无限频率（ε ₀和ε _∞）为150和59，用于的BiFeO ₃，22 000和14的Bi ₂铁₄ O ₉。分析了铋铁氧体悬浮液在静电场（高达5 kV）中的拉伸，压缩和剪切模式下的电流变特性。已经发现，即使在高分散相浓度（60重量％）下，聚二甲基硅氧烷PMS-300中的BiFeO ₃悬浮液的电流变效应值也很小。相反，高度分散的Bi ₂ Fe ₄ O ₉的悬浮液表现出独特的电流变效应。对于80 wt％的Bi ₂ Fe ₄ O ₉悬浮液，在5 kV电场中的拉伸屈服点达到〜7 kPa，而压缩应力为12 kPa。