Optical and Ferroelectric Properties of ${\hbox {Bi}}_{0.95}{\hbox {Gd}}_{0.05}{\hbox {Fe}}_{1-x}{\hbox {Cr}}_{x}{\hbox {O}}_{3}$

Abstract

In this paper, optical and ferroelectric properties were investigated for gadolinium, ${\hbox {Gd}}^{3+}$ (5 at.%) and chromium, ${\hbox {Cr}}^{3+}$ (0–8 at.%) co-doped of BiFeO$_3$. Chemical solution deposition (CSD) method was employed as compatible device fabrication technology to synthesize Gd and Cr co-doped multiferroic ${\hbox {BiFeO}}_{3}$ $({\hbox {Bi}}_{0.95}{\hbox {Gd}}_{0.05}{\hbox {Fe}}_{1-x}{\hbox {Cr}}_{x}{\hbox {O}}_{3}$ with ${\hbox {x}}$ = 0–0.08). X-ray diffraction (XRD) analysis confirmed a well-defined crystalline phase with a tendency towards structural change from rhombohedral to orthorhombic symmetry. Crystallite size was found to reduce substantially from 34 to 13.5 nm with increasing the doping concentration of ${\hbox {Cr}}^{3+}$. The field emission scanning electron microscopy (FESEM) demonstrated a significant reduction in grain size of doped ${\hbox {BiFeO}}_{3}$ compared to un-doped one following the trend obtained from XRD results. Ferroelectric nature of samples was obtained from polarization versus electric field measurements. Improved ferroelectric order was displayed in co-doped ${\hbox {BiFeO}}_{3}$ with a maximum remnant polarization of 0.23 μ${\hbox {C}}/{\hbox {cm}}^2$. Diffuse reflectance measurement by UV–Vis–NIR spectroscopy of Gd$^{3+}$ and ${\hbox {Cr}}^{3+}$ co-doped ${\hbox {BiFeO}}_{3}$ has shown a significant reduction in the optical band-gap energy $({\hbox {E}}_{g})$ to 1.71 eV compared to 2.03 eV of pure BiFeO$_{3}$ counterpart.