Near-surface structural changings in paratellurite crystals under external electric field
This work describes the results of the near-surface structural changes caused by the migration of oxygen vacancies in paratellurite (α-TeO2) single crystals obtained by the in situ X-ray diffraction technique under a constant electric field. This process has a reversible character  and its dynamics (duration is about tens of minutes) corresponds with the conductivity kinetics.
When the electric field is applied along the  and  directions, two types of processes occurs simultaneously which were recorded through measurement of the diffraction curve evolution . The first one is caused by the piezoelectric lattice deformation due to a sharp increase in the strength of the field near both surfaces. At the same time, the change in the lattice parameter near the anode (the surface of a crystal with a positive external charge) was revealed, that is caused by a local rearrangement of the crystal structure due to the counter migration of oxygen ions and oxygen vacancies in the external electric field and their accumulation at the dielectric-metal interface. The velocity of the process depends on the crystallographic direction, however the application of electric field in the non-piezoelectric direction  does not affect on the rocking curve shape.
This work was partially supported by the Russian Foundation for Basic Research (RFBR grant № 18-32-00410 mol_a, 16-32-60045 mol_a_dk) and by the Federal Agency of Scientific Organizations (Agreement № 007-ГЗ/Ч3363/26) in part of crystal growing and sample preparation.
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