  This paper combines experimental and modelling studies to provide a detailed
examination of the influence of porosity volume fraction and morphology on the
polarisation-electric field response of ferroelectric materials. The broadening
of the electric field distribution and a decrease in the electric field
experienced by the ferroelectric ceramic medium due to the presence of
low-permittivity pores is examined and its implications on the shape of the
hysteresis loop, remnant polarisation and coercive field is discussed. The
variation of coercive field with porosity level is seen to be complex and is
attributed to two competing mechanisms where at high porosity levels the
influence of the broadening of the electric field distribution dominates, while
at low porosity levels an increase in the compliance of the matrix is more
important. This new approach to understanding these materials enables the
seemingly conflicting observations in the existing literature to be clarified
and provides an effective approach to interpret the influence of pore fraction
and morphology on the polarisation behaviour of ferroelectrics. Such
information provides new insights in the interpretation of the physical
properties of porous ferroelectric materials to inform future effort in the
design of ferroelectric materials for piezoelectric sensor, actuator, energy
harvesting, and transducer applications.
