More efficient charging of ferroelectrets via tuning of the Paschen breakdown Available to Purchase

Charging by means of dielectric barrier discharges (DBDs) is a critical step in the preparation of ferroelectrets (also called piezoelectrets). Triggering of the DBD charging in ferroelectrets is governed by Paschen's law. The Paschen-breakdown voltage $Vb$ of common gases exhibits a U-shaped dependence on the product of gas pressure p and electrode spacing d (internal-cavity height in the present ferroelectret context). This allows for a more efficient charging strategy for ferroelectrets whose pd value at atmospheric pressure is different from the $(pd)min$ value of the Paschen-breakdown curve. For easier triggering of the DBD charging, the pd is adjusted toward $(pd)min$ (corresponding to $Vb, min$ of the Paschen curve) by controlling the gas pressure in the cavity. Subsequently, pd is restored to its value at ambient pressure under the charging voltage in order to obtain a high remanent polarization. The proposed charging scheme is easy to operate and can significantly improve the charging efficiency of ferroelectrets with a wide range of cavity geometries.