Electrorheological Fluids Based on Bismuth Ferrites BiFeO3 and Bi2Fe4O9

• Published in: Russian journal of inorganic chemistry 2020-08, Vol.65 (8), p.1253-1263
• Main Authors: Egorysheva, A. V., Kraev, A. S., Gajtko, O. M., Baranchikov, A. E., Agafonov, A. V., Ivanov, V. K.
• Format: Article
• Language: English
• Subjects: Bismuth ferrite; Chemistry; Chemistry and Materials Science; Compressive properties; Dielectric loss; Dielectric properties; Dispersion; Electric fields; Electrorheological fluids; Frequency ranges; Inorganic Chemistry; Inorganic Materials and Nanomaterials; Permittivity; Polydimethylsiloxane; Yield point
• ISSN: 0036-0236; 1531-8613
• DOI: 10.1134/S0036023620080045

A comparative analysis has been made for the dielectric and electrorheological properties of suspensions of highly dispersed powders of bismuth ferrites BiFeO 3 and Bi 2 Fe 4 O 9 in polydimethylsiloxane PMS-300. Dielectric characteristics (dielectric constant, dielectric loss tangent) for the suspensions in frequency range 2.5–10 6 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 (ε 0 and ε ∞ ) are 150 and 59 for BiFeO 3 , 22 000 and 14 for Bi 2 Fe 4 O 9 , 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 BiFeO 3 suspensions in polydimethylsiloxane PMS-300 are small even at high concentrations of disperse phase (60 wt %). On the contrary, the suspensions of highly disperse Bi 2 Fe 4 O 9 exhibit distinct electrorheological effect. For 80 wt % Bi 2 Fe 4 O 9 suspension, the tensile yield point reached ~7 kPa in electric field of 5 kV, while compressive stress was 12 kPa.