Multiferroic Composite Of BFO Lab Report

Multiferroic composite of 0.2 LNMFO + 0.8 BFO with LNMFO as ferrimagnetic and BFO as ferroelectric phase were prepared by the standard solid state reaction method. To prepare BFO stoichiometric amounts of high purity Bi2O3, and Fe2O3 were weighed and mixed thoroughly in acetone media for 5–6 h. The mixed powder of BFO was calcined at 800 °C in a closed alumina crucible for 4 h and then pre-sintered at 850°C for 4 h. High purity Li2CO3, NiO, MnCO3 and Fe2O3 were mixed in stoichiometric amounts to prepare LNMFO by the same procedure as BFO. The well mixed powder was calcined at 800 °C and pre-sintered at 1200 °C for 4 h. After pre-sintering, powders were again grinded in an agate mortar. The obtained powders of BFO and LNMFO were mixed in weight …show more content…
Energy Dispersive X-ray Spectroscopy (EDX) analysis was done by using the EDX system supplied with the FESEM. The bulk density (ρB) of the composite was determined using the relation: ρ_B=m/(〖πr〗^2 t) where m is the mass, r is the radius and t is the thickness of the pellet. The X-ray density of the composite is given by the formula, ρ_x (composite)=(M_1+M_2)/(V_1+V_2 ) where M_1 is (1-x) times molecular weight of BFO and M_2 is x times molecular weight of LNMFO,〖 V〗_1=M_1/ρ_x (ferroelectric) and V_2=M_2/ρ_x (ferrite) x is the weight fraction of LNMFO in the composites [22]. The ρx is measured by the general formula,〖 ρ〗_x=nM/(N_(A ) V), where n is the number of atoms in a unit cell, M is the molar mass of the sample, NA is Avogadro's number and V is the volume of the unit cell. The porosity of the samples was calculated using the relation, P(%)=(ρ_x-ρ_B)/ρ_x ×100. The dielectric and magnetic properties were carried out using WAYNE KERR 6500B Impedance Analyzer. To measure dielectric properties the samples were painted by conducting silver paste on both sides. The dielectric constant (ε′) was calculated from the capacitance using the formula: ε^'=Ct/(ε_0 A), where C is the capacitance of the pellet, A is the cross-sectional area of the electrode and ε_0 ( = 8.85×10-12 F/m) is the permittivity in free space. The relation: σ_ac=ω〖ε^' …show more content…
1 shows the XRD pattern of 0.2BFO + 0.8LNMFO composite. It is observed from the XRD pattern that the composite confirms the presence of the ferrite and ferroelectric phases. The lattice parameter of ferroelectric phase is measured by solving different sets of three equations corresponding to three consecutive peaks. Then by taking the average the accurate value of the lattice parameter is obtained. The values of lattice parameter of all the peaks for the ferrite phase obtained for each reflected plane are plotted against the Nelson–Riley function [17]:F(θ)=1/2 ((〖cos〗^2 θ)/sinθ+(〖cos〗^2 θ)/θ), where θ is Bragg's angle. A straight line has been obtained and the accurate value of the lattice parameter has been determined from the extrapolation of these lines to