Using were prepared by applying a uniaxially

Using standard solid
state reaction method, multiferroic composite of 0.2 LNMFO + 0.8
BFO with LNMFO as ferrimagnetic and BFO as ferroelectric phase were prepared.
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 BFO powder was calcined at 800°C for 4 h and then
pre-sintered at 850°C for 4 h. To prepare LNMFO high purity Li2CO3,
NiO, MnCO3 and Fe2O3 were mixed in stoichiometric
amounts by the same procedure as BFO. The mixed powder of LNMFO was calcined at
800 °C and pre-sintered at 1200 °C for 4 h. After pre-sintering, powders of BFO
and LNMFO were again grinded in an agate mortar. To prepare 0.2BFO + 0.8LNMFO
composite, the obtained BFO and LNMFO powders were mixed in weight proportions
in acetone media for 3–4 h. From the powders of composite pellet- and
toroid-shaped samples were prepared by applying a uniaxially pressure of 55MPa.
Finally at various sintering temperatures (Ts) the samples were
sintered for 4 h.

 

 

2.2 Characterizations

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X-ray
diffraction (XRD) was studied using a X-ray diffractometer with CuK?
radiation (?= 1.5418 Å). Surface morphology was studied by Field Emission
Scanning Electron Microscopy (FESEM, model JEOL JSM 7600F). Energy Dispersive
X-ray Spectroscopy (EDX) analysis was done using the EDX system supplied with
the FESEM. The formula:

 where m is the mass, r
is the radius and t is the thickness of the pellet, was used to obtain the bulk
density (?B) of the composite. The X-ray density of the
composite is given by the formula,

 where

 is 0.8 times molecular weight of BFO and

 is 0.2 times molecular weight of LNMFO,

(ferroelectric) and

 (ferrite) 22. The ?x was
measured using the formula,

, 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. Using the relation,

, the porosity of the composite
was calculated. The electric and magnetic properties were carried out using
WAYNE KERR 6500B Impedance Analyzer. The samples were painted by conducting
silver paste on both sides to measure dielectric properties. The dielectric
constant (??) was calculated using the formula:

, where C is the
capacitance of the pellet, A is the cross-sectional area of the electrode and

 (
= 8.85×10-12 F/m) is the permittivity in free space. To calculate
the ac conductivity (?ac), the relation:

, where, ? is the angular frequency and tan? is the dielectric loss, was used.
The Magnetic hysteresis loop was observed using a vibration sample magnetometer
(VSM, model Micro Sense, EV9). The real part of the complex initial
permeability

 was
calculated using the relation:

, where Ls is
the self-inductance of the sample and

 is derived geometrically. Here, L0 is the inductance of the winding
coil without the sample, N is the number of turns of the coil (N = 4), S is the
area of cross section and

 is the mean diameter of the toroidal sample,
where d1 and d2 are the inner and outer diameter of the
toroidal sample, respectively 15. The output
voltage generated from the composite was measured using a Keithley multimeter
(Model 2000) with of dc magnetic field. ME voltage coefficient (?ME) was calculated using
relation 16

, where

is the ME voltage across the
sample surface and h0 is
the amplitude of the ac magnetic field.