Novo triodo corona e sua aplicação no estudo das propriedades elétricas do polímero pvdf. / New corona triode and application at the study of electrical properties of pvdf polymer.

AUTOR(ES)
DATA DE PUBLICAÇÃO

1990

RESUMO

This work describes a corona triode setup which allows charging thin dielectric films with a constant current and the simultaneous measurement of the sample surface potential. The charge current is kept constant by controlling the gride voltage, from which the sample potential is also derived. With the experimental setup we were able to obtain charging currents from 1 nA to 1 μA and getting potential UP to ± 6 kV. The electric characteristics of the system and its performance is also shown and discussed. The corona triode was used to study the electric conduction and the ferro-electricity of the PVDF (polyvinylidene fluoride) polymer. The results show that the conduction is dominated by the transport of an excess of charge. Formation of a permanent polarization during charging may be deduced from the potential build up curve and confirmed by piezoelectric measurements. We also discuss the structural transitions due to the electric field showing that both reversible and irreversible transitions may occur. Together with ferro-electric components we infer that a reversible polarization is also occurring in the material. Finally we present a theoretical model describing the sample potential build up including in it the ferroelectric switching.

ASSUNTO(S)

corona triode triodo corona electrical properties propriedades elétricas polymer polímero

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