Thee is a lot of published literature on PZT fibers regarding their preparation and the characterization of their dielectric properties. You can refer to these papers, and probably figure out hot to make the sample out of a fiber for the dielectric measurements. Maybe they have described how they made their samples.
cut a miniature cylinder out of your fiber. Make contact either end. Know the dimensions of your little tiny cylinder. Attach wires at both the contacts. and go ahead with the dielectric measurement.s
sir important factors involved for dielectric measurements are area and thickness of nanofibers, which seems difficult/not proper in case of nano fibers