The dielectric constant of PZT nanofiber at visible and NIR wavelengths

Dielectric constant measurements of PZT nanofiber were performed at visible and near infrared wavelengths using ellipsometry. The nanofibers, formed by electro-spinning with diameters ranging from 10 to 100 nm were collected on Si wafers for the measurement. A nominal 150 nm PZT thin film was also fabricated on Si and measured in parallel for comparison. Several models were developed to fit the ellipsometry measurements and the results show consistent values of dielectric constant in the range of −1 to 6 over the frequency range for both the fiber and the film. The complex dielectric properties are useful for matching optical impedances as well as analyzing the material for potential applications including combining with other materials to form metamaterials. At certain wavelengths negative permittivity and epsilon-near-zero characteristics are identified.