Experimental determination of flexoelectric coefficients in SrTiO3, KTaO3, TiO2, and YAlO3 single crystals

We report experimental values for the flexoelectric responses of ${\mathrm{SrTiO}}_{3}, {\mathrm{KTaO}}_{3}, {\mathrm{TiO}}_{2}$, and ${\mathrm{YAlO}}_{3}$ single crystals using a three-point bending approach. We find all samples possess a linear flexoelectric response with effective short-circuit flexoelectric coefficients $\ensuremath{\sim}|1--10|\phantom{\rule{0.16em}{0ex}}\mathrm{nC}/\mathrm{m}$. Flexocoupling voltages computed from these measured effective flexoelectric coefficients are found to significantly vary across the investigated materials and refute the previous suggestions that they should be $\ensuremath{\sim}|1--10|$ V. Importantly, we find that low dielectric constant materials can have large flexocoupling voltages exceeding nominal expectations.