Measuring the Permittivity of Ferroelectric Nanoparticles in an Epoxy Composite

Sandia National Laboratories

This project aims to measure the size dependence of the dielectric constant of barium titanate (BTO) nanoparticles in epoxy composites. To accomplish this, we developed improvements to an existing sample fabrication process to reduce defects within the composite and improve yield, as well as improved computational models of particle size, shape, and agglomeration. In previous years, HMC Sandia Clinic teams used a ball milling procedure to reduce particle agglomeration and fabricate composites containing nanoparticles with diameters ranging from 200-nm to 500-nm. However, the dielectric constants for many of these samples did not match the predictions made by computational models that assumed 0% particle agglomeration. We examined the particles at various stages throughout the manufacturing process using DLS and SEM, and used image analysis techniques to extract information on particle size, shape, and agglomeration from microscopy images. This information was then used to inform finite-element computational models. Additionally, we employed a new, low-viscosity epoxy and a rotary evaporator to improve particle dispersion and manufacturing yield. Next semester, we will use these improvements to fabricate composites of nanoparticles with diameters ranging from 50-nm to 500-nm at both 10-vol% and 20-vol% loading. We will measure the dielectric constant of these composites and compare those results with those from refined computational models to determine the dielectric constant of individual BTO nanoparticles.

Advisor(s): Albert Dato and Peter N. Saeta.

Team: Charles Burke Dawson ’19, Alejandro E Baptista ’18, Andrew Mather Bishop ’18, Benjamin I Lehman ’18, Richard Arthur Liu ’18, and Lupe Maria MacIntosh ’18.