  Room temperature dielectric and magnetic properties of BiFeO$_3$ samples,
co-doped with magnetic Gd and non-magnetic Ti in place of Bi and Fe,
respectively, were reported. The nominal compositions of
Bi$_{0.9}$Gd$_{0.1}$Fe$_{1-x}$Ti$_x$O$_3$ (x = 0.00-0.25) ceramics were
synthesized by conventional solid state reaction technique. X-ray diffraction
patterns revealed that the substitution of Fe by Ti induces a phase transition
from rhombohedral to orthorhombic at x $>$ 0.20. Morphological studies
demonstrated that the average grain size was reduced from $\sim {~}$1.5 $\mu m$
to $\sim {~}$200 $nm$ with the increase in Ti content. Due to Ti substitution,
the dielectric constant was stable over a wide range of high frequencies (30
kHz to 20 MHz) by suppressing the dispersion at low frequencies. The dielectric
properties of the compounds are associated with their improved morphologies and
reduced leakage current densities probably due to the lower concentration of
oxygen vacancies in the compositions. Magnetic properties of
Bi$_{0.9}$Gd$_{0.1}$Fe$_{1-x}$Ti$_x$O$_3$ (x = 0.00-0.25) ceramics measured at
room temperature were enhanced with Ti substitution up to 20 $\%$ compared to
that of pure BiFeO$_3$ and Ti undoped Bi$_{0.9}$Gd$_{0.1}$FeO$_3$ samples. The
enhanced magnetic properties might be attributed to the substitution induced
suppression of spiral spin structure of BiFeO$_3$. An asymmetric shifts both in
the field and magnetization axes of magnetization versus magnetic field (M-H)
curves was observed. This indicates the presence of exchange bias effect in
these compounds notably at room temperature.
