Towards a better understanding of dielectric barrier discharges in ferroelectrets: Paschen breakdown fields in micrometer sized voids
- Department of Physics and Science of Advanced Materials Program, Central Michigan University, Mount Pleasant, Michigan 48859 (United States)
Charged cellular polypropylene foams (i.e., ferro- or piezoelectrets) demonstrate high piezoelectric activity upon being electrically charged. When an external electric field is applied, dielectric barrier discharges (DBDs) occur, resulting in a separation of charges which are subsequently deposited on dielectric surfaces of internal micrometer sized voids. This deposited space charge is responsible for the piezoelectric activity of the material. Previous studies have indicated charging fields larger than predicted by Townsend's model of Paschen breakdown applied to a multilayered electromechanical model; a discrepancy which prompted the present study. The actual breakdown fields for micrometer sized voids were determined by constructing single cell voids using polypropylene spacers with heights ranging from 8 to 75 μm, “sandwiched” between two polypropylene dielectric barriers and glass slides with semi-transparent electrodes. Subsequently, a bipolar triangular charging waveform with a peak voltage of 6 kV was applied to the samples. The breakdown fields were determined by monitoring the emission of light due to the onset of DBDs using an electron multiplying CCD camera. The breakdown fields at absolute pressures from 101 to 251 kPa were found to be in good agreement with the standard Paschen curves. Additionally, the magnitude of the light emission was found to scale linearly with the amount of gas, i.e., the height of the voids. Emissions were homogeneous over the observed regions of the voids for voids with heights of 25 μm or less and increasingly inhomogeneous for void heights greater than 40 μm at high electric fields.
- OSTI ID:
- 22273532
- Journal Information:
- Journal of Applied Physics, Vol. 115, Issue 16; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
BREAKDOWN
CAMERAS
CHARGE-COUPLED DEVICES
ELECTRETS
ELECTRIC DISCHARGES
ELECTRIC FIELDS
ELECTRODES
ELECTRONS
FOAMS
PASCHEN LAW
PHOTON EMISSION
PIEZOELECTRICITY
POLYPROPYLENE
SPACE CHARGE
VISIBLE RADIATION
VOIDS
WAVE FORMS