Precision Nanoparticles for High Performance Devices

Nanoparticle synthesis chemistry has developed tremendously over the last several decades, achieving great control over size, shape, and composition. This has led to much greater understanding of material optical, electronic, and surface properties, and myriad applications, from solar cells and photodetectors to medical therapy. Currently, processes for building nanoparticles are largely based on bottom‐up chemical syntheses in either batch or flow cell configurations, requiring high temperature and, in some cases, high pressure. Residual solvents from these processes adversely affect the environment and disposal is costly. By exposing single‐source precursors—molecules containing elements connected by a single chemical bond—to carbon dioxide in a supercritical state, DOE researchers have developed a process to produce uniform nanoparticles at desired sizes. Instead of using high temperature, the process takes place at around 65 degrees Celsius, saving significant amounts of energy. While the patented method using supercritical fluids was originally conceived as a process for making nanomaterials for cost‐effective and high‐efficiency photovoltaic cells, the process is recognized to have potential in producing nanoparticle‐based materials for microelectronics, magnets, and thermoelectric devices, as well as for catalysts in the advanced manufacturing of platform chemicals. To address a worldwide need for a wideband low‐loss radome to protect radio frequency (RF) emitters and receivers in harsh environments, Voxtel proposes to commercialize the DOE‐developed supercritical fluid extraction (SFE) methods of fabricating nanoferrite nanoparticles for use in the additive manufacture of high‐efficiency nanocomposite radomes for the 10MHz to 28 GHz band, including the emerging 5G spectrum. Ideally, radomes would be fabricated from a material that protects the antenna but does not suffer from reflectance and attenuation losses common to existing materials. Nanocomposite materials are advantageous because of the unique properties of nanoparticles, e.g., chemical, optical, thermal, electrical, magnetic, etc. In Phase I, we will perform technology transfer of the DOE technologies to build SFE fabrication equipment capable of meeting the program technical objectives. We will first synthesize and fabricate a series of common nanocrystal materials, such as PbS, to demonstrate the ability to make commercial quantities of high precision. We will compare our results to alternative methods, including continuous flow reactors and batch reactors. We will then synthesize a simple ferrite precursor to demonstrate the feasibility of using the SFE precision‐ nanoparticle process to produce simple ZnFe2O4 nanoferrites, sized 60  1nm. These nanoparticles will be incorporated in nanocomposite radome prototypes and tested. Finally, we will design a fully complex precursor for the more complex NiZnFe2O4 nanoparticles. In Phase II, we will: further refine the Phase I NiZnFe2O4 precursor chemistry; create a scaled‐up version of the SFE platform capable of generating kilograms/month of the precision nanoferrite; and, through careful process control, demonstrate those volumes of NiZnFe2O4 with  0.2nm control, which will be used in the fabrication of cost‐effective novel energy‐efficient all‐weather antenna system covers. Environmental and reliability testing will be performed.