Researchers from the University of Wisconsin–Madison have discovered that a perovskite material could greatly enhance the technology of vacuum electronics. The material is capable of promoting the output power of the electron beam, and enables remote sensing and long-distance communications for a much lower energy cost than currently spent.

The researchers received a $1.3 million grant from the Defense Advanced Research Projects Agency. They aimed to synthesize large quantities of the material and additionally analyze its properties. They also hope to locate other applications where this concept can be utilized.

The devices that would rely on UW–Madison’s perovskite research would be able to take useful energy from electron streams flowing via a vacuum and are called vacuum electronics. Vacuum electronic devices may have a variety of functions, from spotting distant objects using radar, to speeding up particles in research reactors, to communicating with interstellar probes.

Since electrons moving within sealed vacuums do not meet any resistance, vacuum electronic devices are outstandingly efficient. The devices are driven by charged beams, which originate from sources called cathodes. The majority of cathodes are manufactured from metals that produce electrons from their surface when exposed to high temperature heat. The higher the emission level, the stronger the electron beam. However, a number of metals do not discharge large quantities of electrons from their surfaces, even at 1,000°C.

The power per unit volume required out of a satellite transmitter is huge. However, the size and power budget are both limited because payload is very expensive in a rocket, and you can only harness a meager amount of energy from the sun. The researchers aimed to obtain additional electronic bang for the input power investment, and therefore set out to discover novel materials that could behave as sources of electron.

Several of the vacuum electronic devices produce beams by heating tungsten to high temperatures, similarly to the way filaments in incandescent light bulbs generate light. In that case, the glow actually represents counterproductive energy loss for the functioning of an electron beam, so tungsten cathodes normally are given a thin coating of barium oxide, which helps them to emit electrons rather than just light up. Since barium oxide is volatile, the coating rips off from the surface when exposed to high temperatures, thus deforming the cathode over time.



Certain substitute cathode materials have been found in the past, but none of them can dependably perform better than existing technologies. The trial-and-error method of detecting and characterizing candidates from a wide range of probable combinations is a tiresome one, but the team in this study may have identified a glowing candidate.

Using a basic method known as density functional theory, the team solved quantum mechanical equations that manipulate the materials’ atomic properties. Advanced high-throughput computing permitted them to foretell the bulk performance of candidate compounds and quickly balance potential materials. This method - tough-force computational comparison informed by realistically chosen parameters - picked out a promising prospect that could be better than the state-of-the-art cathodes.

The team is involved in creating strategies to fabricate huge quantities of the pure material and additionally describe its properties. The researchers are also partnering with the Wisconsin Alumni Research Foundation to patent the material.

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