Poling of ferroelectric composites

Abstract

In 0-3 nanocomposites of lead titanate (PT) in polivinylidenefluoride trifluoroethylene (PVDF-TrFE) it is possible to polarize the inclusions and the matrix separately. The pyroelectric coefficients of both components have the same sign, but the piezoelectric coefficients have the opposite sign. If matrix and inclusions of a composite of PT in PVDF-TrFE are polarized in the same direction, then the pyroelectric response of both components overlays constructively, the piezoelectric response destructively. By poling in opposite directions a material with reduced pyroelectric but increased piezoelectric sensitivity is produced. Under special poling conditions and for a certain ceramic volume fraction the pyroelectric coefficient vanishes completely for the antiparallel poled case but is piezoelectric with a piezoelectric coefficient of 20 pC/N. Such a material with internally compensated pyroelectricity is of high interest for the application in piezoelectric sensors were the cross sensitivity of piezoelectric sensors to temperature changes is often a large obstacle for their practical use.