Flexoelectric domains in a binary mixture of nematics

Flexoelectric domains formation in mixture of nematic liquid crystals (nlc) mbba and 5cb with anisotropy of dielectric permeability $\varepsilon_a\approx$ 0 under the action of dc electric voltage is investigated. threshold characteristics of flexoelectric domains formation (threshold voltage and spatial period) in the studied mixture are measured. the difference of flexoelectric coefficients $|e_1-e_3|$ is determined. it is shown that in the mixture of nematics with $\varepsilon_a \approx$0, the threshold voltage is determined only by the ratio $k/(e_1-e_3)$ ($k$ – average elastic constant), which allows to calculate the difference in flexocoefficients $|e_1-e_3|$ directly, excluding the properties of substrate surfaces. the definition method of the flexoelectric coefficients, proposed and approved in paper, can be useful for the new synthesized nlc with $\varepsilon_{a}<$ - 0.5.