Synthesis of complex oxide compounds of strontium aluminogallonickelates with a perovskite-like structure was carried out by the standard solid state reactions using aqueous solutions of metal nitrates. The samples were investigated using powder X-ray diffraction on an HZG4A diffractometer (CuKα-radiation, Ni-filter).
The effect of direct (DC) and alternating (AC) electric fields on the rheological properties of electrorheological fluids has been studied. The ERF contained 20 wt % of the filler Sr₃Ga_0.5Al_0.5NiO₇ or Sr₃GaAl_0.8Ni_0.2O₇ as the dispersed phase. Mobil 22 synthetic oil was as the dispersion medium. To determine the effect of a DC electric field, a rotary viscometer “Rheotest 2.1” was used with a coaxially cylindrical cell modified for the electric field. The electric field strength varied from 0 to 4.0 kV/mm. The shear rate in all experiments was 17.2 s^-1, T = 20°C.
To determine the features of the ERF’s rheology in an AC electric field, various waveforms were set: sine wave, square wave with different duty cycles. The frequency of the AC field was 0.01–1000 Hz. The AC field strength was 1, 2, and 3 kV/mm, T = 20°C.
Analyzing the electrorheological behavior of the ERF with different compositions of perovskite-like oxides under the influence of DC and AC electric fields, we can conclude that the ERF containing the complex oxide Sr₃GaAl_0.8Ni_0.2O₇  has a higher ER-response in a DC field than in an AC one at any frequency and waveform. The ERF containing the complex oxide Sr₃Ga_0.5Al_0.5NiO₇ has a higher ER-response in an AC field than in a DC field. Possibly, such different ER activity in different electric fields is related to the different structure of the material.
The dielectric properties of the ERF were measured in the frequency range
0.1–1000 kHz. Dielectric spectra ε´(f), ε˝(f) of the ERF indicate structural polarization with a relaxation frequency f_rel < 0.1 kHz.
Thus, the results obtained require taking into account the influence of the structures of complex oxide compounds and the magnitude of the electric field when using controlled ERFs in dampers, precision instrumentation, hydraulic automation and vibration protection devices.

Electrorheological fluid;complex oxide;perovskite-like structure;rheological behavior;electric field strength