New Army Antiferroelectric Research Offers Breakthrough Energy Storage Potential

U.S. Army Combat Capabilities Development Command, known as DEVCOM, recently announced researchers from the Army Research Laboratory had demonstrated a new antiferroelectric material process that could revolutionize the way technologies store and release large amounts of electrical power. 

The process involved developing a new method of antiferroelectric thin film called “lead hafnate,” or PbHf03. According to Army Research Labs, the breakthrough represents the first time researchers have ever produced a thin antiferroelectric film from the relatively obscure chemical element hafnium. 

“When you need a burst of electrical power like in a defibrillator or a railgun, antiferroelectrics are a good way to get raw watts of pulse power out,” said Army materials engineer, Dr. Brendan Hanrahan, in a press release. “Anti-ferroelectrics also naturally absorb oscillating signals, which make them excellent electronic filters.”

Compared to the atomic-scale pattern of a non-polar dielectric material (left) and a polarized dielectric material (right), the atomic-scale pattern of an antiferroelectric material (center) demonstrates an alternating pattern in terms of the charge’s orientation. (Image Source: Army Research Labs)


Ferroelectricity relates to certain materials that have a spontaneous electric polarization that can be reversed by applying an external electric field. 

A ferroelectric material consists of an ordered crystalline array of electric dipoles, which all point in the same direction. In contrast, an antiferroelectric material is one in which the structure of adjacent dipoles is oriented in opposition directions, roughly analogous to a checkerboard pattern. Since adjacent dipoles cancel each other out, the macroscopic spontaneous polarization of antiferroelectric materials is zero. 

The antiferroelectric properties of lead hafnate were first theorized in 1953, when researchers identified lead zirconate, or PbZr03, as an antiferroelectric material. However, at the time, due to the high cost of hafnium, lead zirconate became the prevailing antiferroelectric material used in the manufacture of a wide range of electronics. 

“Lead hafnate is almost absent from the literature, because getting pure enough hafnium at the time was incredibly difficult,” a statement by Hanrahan reads. “Lead zirconate and lead hafnate were almost in equal esteem at the very outset, but lead zirconate was the only one anyone ever used because zirconium was a lot easier to come by than hafnium.”

In the early 2000s, hafnium became more readily available when the material became an important component of gate insulators in integrated circuits and semiconductor devices. Hafnium was finally confirmed to have antiferroelectric properties by a team of Russian scientists in 2019. 

With hafnium no longer scarce, Army researchers began examining how it could be employed to produce new materials that could open the door for a host of novel high-energy technologies.

Using atomic layer deposition, a process commonly used by companies like Intel and Samsung to create an antiferroelectric thin film for silicon wafers, Army researchers began testing the possibility of developing a thin antiferroelectric film made from hafnium.

The researcher’s efforts paid off when they demonstrated the ability to produce a thin layer of antiferroelectric lead hafnate successfully. Hanrahan says he and his colleagues will continue to fine-tune the unique properties of lead hafnate to transition the technology to small businesses.

Army Research Lab says the breakthrough could allow engineers to take advantage of the widespread availability of hafnium to produce a more powerful antiferroelectric material. Ultimately, this could lead to the development of technologies capable of maintaining and controlling more significant amounts of energy than devices in use today.

“We have proven the antiferroelectric property, but now there is a lot of application-specific tuning that needs to happen,” said Hanrahan in the ARL release. “Lead hafnate can be used for applications in energy storage, thermal sensors, radio and more. It all depends on how we want to use it.”

Follow and connect with author Tim McMillan on Twitter: @LtTimMcMillan

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