Thermal Wave Induced Edge Electrical Field of Pyroelectric: Spatial Pattern Mapping and Effect of Ambient Conditions

TL;DR

This study experimentally and theoretically investigates the edge depolarizing electric field (EDEF) in pyroelectric LiTaO3 crystals induced by thermal waves, analyzing spatial patterns and the influence of ambient conditions like air pressure and surface coatings.

Contribution

It provides the first experimental validation of theoretical models of EDEF in pyroelectrics and explores how ambient conditions affect EDEF magnitude and distribution.

Findings

EDEF magnitude agrees with theoretical predictions

EDEF increases as air pressure decreases

Teflon coatings significantly enhance EDEF

Abstract

We have recently analyzed theoretically the main characteristics of the edge depolarizing electric field (EDEF), in the vicinity of a non-polar face of a pyroelectric. In this work we measured and characterized the EDEF, excited by a harmonical thermal wave. We present here experimental results obtained on a pyroelectric crystal LiTaO3, confirming our theoretical predictions. We present the theoretical analysis and description of the thermal wave and the induced harmonically varying EDEF. The calculations assume an equivalent circuit of a pyroelectric capacitive current source. The measured magnitude of the EDEF and its spatial variation agree well with the theoretical model. The effect of the air pressure at the pyroelectric/air interface, on the EDEF, was determined in the interval 10^3 - 10^-6 torr. We found that EDEF increases significantly with decreasing air pressure, presumably due to diminishing of adsorption screening at the polar faces. Teflon plates, covering the polar faces, prevent accumulation of screening charged particles, resulting in a drastic increase of EDEF.