A Novel Class of Ceramic-glass Nanocomposite Dielectric Materials for High-Energy-Density, High Temperature Capacitors
Funded by Simulation and Training Technology Center (STTC)
Project Summary
This SBIR project involved developing and demonstrating a novel class of ceramic-glass nanocomposite dielectric materials with a focus on the development of Ca(Ti, Zr)O3-glass nanocomposites, which will lead to the development of a new class of high energy density, high temperature stable multilayer ceramic capacitors (MLCCs). This class of materials is expected to offer better performance over currently used dielectric materials (e.g. BaTiO3), including higher breakdown strength (EB), higher energy density, better performance at elevated temperatures, lower sintering temperature, and potentially lower costs. Therefore, these dielectrics and the resultant MLCCs will be attractive for use in pulsed power and power conditioning applications in both military systems (such as new radar platforms, rail guns, and superconducting electromagnets for degaussing, ground/sea vehicles, and other weapon platforms) and commercial systems (such as regenerative breaking and other electrically-based energy recovery systems used in vehicles and trains).
The research conducted in Phase I has well demonstrated the technical feasibility of the proposed technology through material design, processing, optimization, and characterization. The key technical issues related to the material processing have been well addressed. Preliminary optimization on material composition and processing parameters has been conducted with an aim of achieving improved performance. Characterization on both microstructure and dielectric properties of the resultant materials has been well conducted. Microstructural analysis indicated the formation of submicron-, nano-scale CaTi0.8Zr0.2O3 particles. Dielectric testing and results showed that very promising performance has been successfully achieved, including high breakdown strength (EB > 0.68 MV/cm, which was achieved using disc samples with ~0.44 mm thickness; which further can be easily extended to EB > 1.10 MV/cm using thinner samples, e.g., ~ 10-50 µm), moderate dielectric constants (εr ~ 60 – 80), promising energy density (~1.36 J/cc at achieved EB, and > 4.8 J/cc if thinner samples are used), low losses (tan δ < 4 × 10-3), low temperature coefficient of capacitance (TCC within ±15% from -50°C to 200°C, which means the resultant MLCCs can be potentially qualified as X9R), and reduced sintering temperatures (~1050 °C). These results are among the best results as reported in the latest literature. It should be noted that the dielectric materials having been investigated can be produced through a cost-effective and scalable process, which is very suitable for a scaled-up mass production.
At the end of this Phase I project, our research has led to the feasibility demonstration of a novel class of ceramic-glass nanocomposite dielectric materials and the resultant MLCC power capacitors with very promising properties. In addition, Phase I research has set forth the direction for future material optimization (including refinement on both composition and processing) and scaled-up production. Consequently, the investigative study carried out in Phase I has established a solid technical basis for future Phase II of this project, which will focus on MLCC cell/pack demonstration based on further performance improvements, process optimization, and scale up.