  The fundamental aspects of relaxation dynamics in Bi0.9Gd0.1Fe0.9Mn0.1O3
multiferroic system have been reported. The study was carried out employing
dielectric relaxation spectroscopy covering eight decades in frequency 0.01
to106 Hz and in a wide range of temperature 423 K to 153 K, hydrostatic
pressure 0.1 MPa to 1765 MPa and aging time 0 s to 80000 s. The temperature
dependent dielectric response indicates three relaxations processes in the
dynamic window of modulus formalism. Variable range hopping model of small
polarons manifests the bulk conduction mechanism. The bulk and grain boundary
contributions have been estimated using impedance spectroscopy analysis and
reveal that localized process dominates the relaxation. The direct evidence of
glassy feature is established below 200 K by aging experiments. Our findings
provide a potential connection between nearly constant loss features appearing
below 200 K with fastest relaxation of magnitude 0.16 eV. We also discuss the
time temperature superposition behavior using modulus scaling. A pressure
driven normal ferroelectric to relaxor behavior is witnessed above a critical
pressure as a result of relative competition between short range and long range
forces. Our findings focus the role of high pressure as a fundamental bridge
between normal ferroelectrics and relaxors. Intriguingly, there exists a direct
connection between chemical pressure induced by substitution and external
hydrostatic pressure. These findings have robust fundamental importance on
theoretical elucidation of relaxation dynamics in perovskite systems.
