The Nature of Pyroelectric Polarity

Abstract

The concept of spontaneous polarization in the pyroelectrics is called into a question, since omnipresent free electric charges make impossible to maintain any equilibrium and time-stable polarized state. We conjecture in this paper that pyroelectricity in polar crystals and piezoelectricity in polar-neutral crystals are due to hybridized ionic-covalent polarity-activating bonds. When they are in non-excited state, these bonds do not produce electric field, yet they are capable of generating the electric response to uniform non-electric influence, e.g., heat, pressure, etc. This response is described by some models of different electric moments. Different contributors to these moments can be measured using partial limitation of crystal thermal strain. In fact, the proposed approach modifies and extends the known concept of spontaneous polarization. In this context, ferroelectrics are distinguished by the fact that, in the electric field, they reorient their polarity-activating inter-atomic bonds with a non-linear response and hysteresis.