  In this work, the potential to exploit Aurivillius higher order composition
(n=6) given by Bi4Ti3O12-3BiFeO3 as single phase and high temperature
magnetoelectric materials are well explored by elaborately studying the
concerned structure and physical properties. Bi4Ti3O12-3Bi1-xLaxFeO3 (x=0,
0.01, 0.05, 0.1, 0.2) was synthesized via solid-state reaction route and X-ray
diffraction data revealed that the lattice parameters associated with
orthorhombic cell (space group P21am) decrease with increase in La3+ content
confirming the incorporation of La. In the frequency dependent dielectric
measurements, the ferroelectric to paraelectric transition temperature (Tc)
corresponding to the parent (x=0) had two phase transitions vis., 803 K
(broader) and 983 K (sharper) whereas phase transitions are single that
progressively becomes sharper with increase in La substitution. Ferroelectric
switching behavior (polarization (P) versus electric field (E)) was
demonstrated for Bi4Ti3O12-3BiFeO3 and remnant polarization decreased
significantly for La substituted compositions reflecting weaker ferroelectric
ordering. In detailed Zero Field-cooled and Field cooled temperature dependent
magnetization measurements, Bi4Ti3O12-3BiFeO3 exhibited Tc around 296 K. Though
a marginal increase in the magnetization values for La substituted compositions
(x=0.1 and x=0.2), the overall temperature dependent magnetization curves
indicate overall paramagnetic nature. The results are more reflective of the
switching off of the possibilities of long range ferromagnetic ordering with
A-site rare earth doping in these Aurivillius layered compounds.
