A Novel Approach to Improve Properties of BiFeO3 Nanomultiferroics

In this study we report the synthesis of Bi1-xInxFe1-yTiyO3 (0x0.1, 0y0.05) nanoparticles by a simple cost effective solution combustion method. Pure BFO samples shows distorted rhombohedral perovskite structure with space group R3c which is also supported by Fourier transform infrared spectra study. The codoping of In and Ti at A-B sites of BFO (BIFTO) partially distorts the crystal structure, increases the lattice strain, reduces the average particle size (14nm), and increases the Fe3+/Fe2+ ratio which significantly affect the observed results. The saturation magnetization increases significantly upon codoping (4.60emu/gm) by about 12 times than that of pure BFO (0.4emu/gm). The improved ferromagnetic properties upon codoping is further manifestated in large value of linear magnetoelectric coupling coefficient (4.8mV/cmOe) which further provides an indirect evidence for the collapse of space modulated spin structure. The activation energy increases with codoping (0.68eV), although less than 1eV which indicates that the conduction is still dominated by charged defect

Multiferroic and magnetoelectric properties of MnFe2O4/(Pb0.8Sr0.2)TiO3 composite films

MnFe2O4/(Pb0.8Sr0.2)TiO3 (MFO/PST20) heterostructured composite films with three different structures have been grown on Pt/TiO2/SiO2/Si substrates by metal-organic decomposition processing via spin coating technique. The structural analysis revealed that the crystal axes of the MnFe2O4 are aligned with those of the PST20 ferroelectric matrix with obvious interfaces and no diffusions exist in all the three composite films. These composite films exhibit simultaneously multiferroic and magnetoelectric responses at room temperature. The growth structure of MFO and PST20 layers has an effect on multiferroic and magnetoelectric coupling behaviours of the composite films. The bi- and four-layered MFO/PST20 composite films exhibit superior ferroelectric properties compared to the tri-layered film. The increasing MFO and PST20 layers in the composite films enhance ferromagnetic properties and are closely related to the strain release in MnFe2O4 phase. The MFO/PST20 bi-layered composite film shows a high magnetoelectric voltage co-efficient (E) similar to 194 mVcm(-1)Oe(-1) at a dc magnetic field H-dc similar to 2.5 kOe. A significant decrease in (E) value has been observed for tri- and four- layered composite films. A close correlation between phase selective residual stress and magnetoelectric properties has been emerged. The results are reasonably encouraging for employing MnFe2O4 for growing multiferroic-magnetoelectric composite film

Induced magnetoelectric coupling and photoluminescence response in solution-processed CoFe2O4/Pb0.6Sr0.4TiO3 multiferroic composite film

CoFe2O4/(Pb0.6Sr0.4)TiO3 bi-layered composite film exhibits ferromagnetic and ferroelectric responses (M-s similar to 162 emu/cm(3), H-c similar to 1.8 kOe, 2P(r) similar to 8.6 mu C/cm(2) and 2E(c) similar to 634 kV/cm) at room temperature. The temperature dependent dielectric anomaly near magnetic phase transition temperature suggests magnetoelectric coupling effect in the composite film. The maximum MD effect can reach as high as similar to 49% at 3 kOe applied DC magnetic field. The composite film exhibits magnetoelectric voltage co-efficient alpha(ME) similar to 67 mV cm(-1) Oe(-1). The photoluminescence emission bands of the composite film have a significant blue shift as compared to those reported for CFO and PST nanostructures

Dielectric relaxation study of binary mixtures of ethyl alcohol and N, N-dimethylformamide in benzene solution from microwave absorption data

163-167Dielectric constant (Ɛ′) and dielectric loss (Ɛ″) of ethanol (C₂H₅OH) and binary mixtures of ethanol and N, N-dimethylformamide (DMF) in benzene solutions have been measured at microwave frequency 9.883 GHz at different temperatures 25, 30, 35 and 40ºC. Standing microwave techniques and Gopala Krishna’s [Trans Faraday Soc, 33 (1957)767.] single frequency concentration variation method have been used for above measurements. The measured values of Ɛ′ and Ɛ″ have been used to evaluate dipole moment (μ) and relaxation time (). Various thermodynamic parameters (ΔH ΔFand ΔS) for the dielectric relaxation process of binary mixtures containing 50% mole fraction of OH have been calculated using Eyring’s rate equations. Comparison has been made with the corresponding energy parameters for viscous flow process. It is found that the dielectric relaxation process can be treated as the rate process like the viscous flow process. Non-linear variation of relaxation time with molar concentration of ethanol in the whole concentration range of the binary mixture indicates the existence of solute-solute type of molecular association