doi:10.1002/adfm.201901984engFerreiro-Vila, E.Blanco-Canosa, S.Lucas del Pozo, I.Vasili, H.B.Magén, C.Ibarra, A.Rubio-Zuazo, J.Castro, G.R.Morellón, L.Rivadulla, F.Room-Temperature AFM Electric-Field-Induced Topotactic Transformation between Perovskite and Brownmillerite SrFeOx with Sub-Micrometer Spatial ResolutionART-2019-115887Reversible structural transformations between perovskite (PV) ABO3- d and brownmillerite (BM) ABO2.5 (A = Ca2+, Sr2+; B = Fe4+/3, Co4+/3+) oxides can be induced by topotactic oxygen exchange at moderate temperatures under reducing/oxidizing conditions. The combination of a large oxide-ion conductivity and a small free energy difference between the 4+/3+ oxidation states of many 3d transition metal ions enables these topotactic transformations. Herein, it is demonstrated that the electric field produced by a voltage-biased atomic force microscopy tip can induce such transformation between PV SrFeO3- d and BM SrFeO2.5 at room temperature and with sub-micrometer spatial resolution. Interestingly, the structural transformation is kept after the electric field is removed, allowing a nonvolatile control of the local chemical, electrical, optical, and magnetic properties. Thus, the results presented in this paper open the door for the fabrication of stable ionic-based devices through the electric field patterning of different crystallographic phases.2019http://zaguan.unizar.es/record/8849310.1002/adfm.201901984http://zaguan.unizar.es/record/88493oai:zaguan.unizar.es:88493info:eu-repo/grantAgreement/EC/H2020/734187/EU/Spin conversion, logic storage in oxide-based electronics/SPICOLOSTThis project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No H2020 734187-SPICOLOSTinfo:eu-repo/grantAgreement/ES/MINECO/MAT2016-80762-Rinfo:eu-repo/grantAgreement/ES/MINECO/MAT2017-82970-C2-2-RAdvanced Functional Materials 29, 48 (2019), 1901984 [8 pp]by-nchttp://creativecommons.org/licenses/by-nc/3.0/es/info:eu-repo/semantics/openAccess