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Local structural changes due to the electric field-induced migration of oxygen vacancies at Fe-doped SrTiO <sub/>3</sub> interfaces
摘要： We report on our study of dc voltage-induced structural changes at reduced and oxidized Fe-doped SrTiO3 (Fe:STO) electrode interfaces using second harmonic generation (SHG) together with photoluminescence (PL) method. We show that oxygen vacancy defects play a critical role in determining the local electrical and structural properties of interfacial depletion regions at Schottky junctions. The SHG results show that the dc electric field causes oxygen ions and vacancies to displace toward the anode and cathode in the low field regime, respectively. This process forms electrostrictive distortions within local interfacial depletion regions which are described by Fe:Ti-O bond stretching and bending. Differences in the EFISHG responses from the oxidized and reduced crystal interfaces are explained according to local oxygen vacancy concentrations and dynamics and their effects on the Schottky barrier heights and depletion region widths at each interface. These results are further supported by our PL measurements. Oxygen ion migration towards the Fe:STO surface leads to enhanced fluorescence intensities from in-gap acceptor states. We demonstrate that SHG and PL measurements are well suited for understanding and resolving the underlying causes of dielectric breakdown processes and device failure brought on by dc electric field and ionic defect migrations in perovskite-type electroceramics.
关键词： Photoluminescence,Oxygen Vacancy,Electroceramic,Second Harmonic Generation
更新于2025-09-23 15:23:52
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Structural, bulk permittivity and impedance spectra of electronic material: Bi(Fe0.5La0.5)O3
摘要： In the present paper, fabrication and characterization (structural, electrical and ferroelectric properties) of a lead-free lanthanum (La) modified bismuth ferrite electroceramic having composition Bi(Fe0.5La0.5)O3 (BFLO) using various experimental techniques have been reported. BFLO has been synthesized by means of a high-temperature inter-diffusion of oxides method. This investigation mainly aims to correlate the phase formation and physical properties while the Fe-site of bismuth ferrite has partially been replaced by La. The surface micrograph shows the formation of the high dense ceramic sample. Analysis of data of various complex spectroscopies related to modulus and impedance exhibits the relaxation mechanism in this sample is of non-Debye type. The combined effect of grains and grain boundaries has been depicted from the Nyquist plot through the least-squares fitting of suitable circuit model along with the experimental data. The remnant polarization and coercive field decreases as temperature rises which was discerned from the ferroelectric loop obtained at different temperatures. The existence of ferroelectric nature in the sample was postulated from the polarization versus electric field plot.
关键词： Ferroelectric properties,Non-Debye relaxation,Lanthanum modification,Bismuth ferrite,Electroceramic
更新于2025-09-10 09:29:36