An electrical field-induced structural effect in strontium titanate at room temperature

An electric field-induced reversible structural distortion at room temperature is observed at an as-cut single-crystalline SrTiO3 [001] wafer. The structural changes have been characterised in situ by means of X-ray diffraction. It is concluded that the effect requires a distortion of the cubic crystal structure, as it was present only at the rough unpolished side of the wafer. The appearance of the phenomenon was found to depend on the direction of the electric field. Structural changes, depending on the electric field strength, were completely reversible. Regarding the possible electromechanical coupling phenomena, the piezoelectric and electrostrictive effects have to be considered. Cubic SrTiO3 belongs to the centrosymmetric point group $m\overline{3}m$ ; hence, no piezoelectric effect is present, whereas second-order effects like electrostriction may occur. Peculiarities arising as a result of the special constraints are discussed.