Advanced Materials Letters

Growing energy crisis and environmental issues demand alternative source of green energy. In recent years ferroelectrics and multiferroics have got renewed attention for the breakthrough in photovoltaic application. Multiferroic is an appealing class of material, having two or more ferroic properties intimately coupled to each other. Energy harvesting from ferroelectrics and multiferroics is a pioneering field of research by its own, combination of other ferroic properties is a value addition to it. The coupling of ferroic and optical properties has brought a revolution in the field of photovoltaics. This review highlights recent development in the field of ferroelectric-multiferroic photovoltaics and summarizes the electrical, optical and photovoltaic properties of various ferroelctric and multiferroic systems. The different mechanisms and factors that attribute to the photovoltaic phenomena in ferroelctrics and multiferroics are also described here.

LaxBi1-xFeO3 (LBFO) samples were prepared by sol-gel route using citric acid as chelating agent for x = 0.0 - 0.4. The structure, dielectric and magnetic properties of the LBFO compounds were studied and compared with the corresponding properties of the materials prepared by a conventional solid state reaction. The use of the sol–gel method in preparation lowered the reaction threshold temperature by 200 °C. Effects of the preparation routes and conditions on the phase and microstructures of the materials were investigated in this study using XRD and SEM. The pure BFO without bismuth loss, which cannot be prepared by the solid state reaction, was obtained by the sol–gel method. Sol-gel synthesis could yield a pure phase material at relatively lower temperatures while the solid state method yielded powder with a small amount of the secondary Bi25FeO40 phase. Single phase LBFO prepared by sol-gel method (SG) revealed huge value of dielectric constant than same obtained by the solid state reaction method (SS). Maxwell-Wagner type dielectric dispersion is observed in sol-gel method. Dielectric constant and loss tangent are found to be higher for SG as compared to SS. Huge coercivity (HC) of the order of ~ 15 kOe is observed in both SG and SS samples due to the high anisotropy in these samples. The increase in the magnetization is observed due to the destruction of spin cycloid structure. The enhanced properties made LBFO a promising candidate for the applications in novel memory devices and spintronics.

La/Pb co-doped BiFeO3 compounds were prepared by a solid-state reaction. X-ray diffraction of BiFeO3 (BFO), Bi0.725La0.1Pb0.175FeO3 [BLPFO] showed single phase in nature. BFO crystallize in the rhombohedral distorted perovskite structure (space group-R3c) while to that BLPFO crystallize in distorted pseudocubic (Pm-3m) symmetry which has been confirmed by the Rietveld refinement of the room temperature X-ray powder diffraction data. The effect of La/Pb substitution on dielectric constant, and loss tangent, of the samples was studied at room temperature in a wide range of frequency 10 Hz – 1 MHz. The room temperature dielectric constant of BFO (BLPFO) was 120 (200). Ferroelectric measurement reveals remnants polarization of BLPFO is about 0.24 μC/cm 2 at an applied field of 15 kV/cm. Weak ferroelectric effect is observed for co-doped BiFeO3 compound.