Investigation of Local Conduction Mechanisms in Ca and Ti-Doped BiFeO3 Using Scanning Probe Microscopy Approach

Abstract

In this work we demonstrate the role of grain boundaries and domain walls in the local transport properties of n- and p-doped bismuth ferrites, including the influence of these singularities on the space charge imbalance of the energy band structure. This is mainly due to the charge accumulation at domain walls, which is recognized as the main mechanism responsible for the electrical conductivity in polar thin films and single crystals, while there is an obvious gap in the understanding of the precise mechanism of conductivity in ferroelectric ceramics. The conductivity of the Bi0.95Ca0.05Fe1−xTixO3−δ (x = 0, 0.05, 0.1; δ = (0.05 − x)/2) samples was studied using a scanning probe microscopy approach at the nanoscale level as a function of bias voltage and chemical composition. The obtained results reveal a distinct correlation between electrical properties and the type of charged defects when the anion-deficient (x = 0) compound exhibits a three order of magnitude increase in conductivity as compared with the charge-balanced (x = 0.05) and cation-deficient (x = 0.1) samples, which is well described within the band diagram representation. The data provide an approach to control the transport properties of multiferroic bismuth ferrites through aliovalent chemical substitution.

Achieving high microscale photoconductivity in Gd-modified bismuth ferrite via modulating ferroelectric polarization

“…A similar behavior was observed from conductive atomic force microscopy (C-AFM) mapping of the Bi 0.95 Ca 0.05 FeO 2.975 ceramic. 42 This conduction behavior was reported to originate from electron hopping between defects associated with oxygen vacancies, 43 consistent with that of pure BFO. [44][45][46] The photocurrent maps from the unpoled specimen under dark condition and at 800 mW cm À2 and from the poled specimen at 800 mW cm À2 with a bias voltage from 0 V to 10 V are shown in Fig.…”