We report on the preparation of novel electrorheological (ER) fluids based on a nanocrystalline ceria suspension in polydimethylsiloxane (PMS-20 silicone oil). Dielectric relaxation spectra of ER fluids were analyzed in the frequency range from 25 Hz to 106 Hz; the values of dielectric permittivity, dielectric loss tangents and tensile strengths of the prepared ER fluids in applied external electric fields up to 5 kV mm−1 were measured. Relaxation characteristics of the dielectric spectra were interpreted in terms of the Cole–Davidson model. The results obtained indicate that the ceria-based materials exhibit excellent ER performance, which depends strongly on the CeO2 concentration in the fluids. High tensile stress values (more than 20 kPa) were registered for ceria-based ER fluids in 5 kV mm−1 static electric fields.
