Self-Correcting Crystal May Unleash New Wave of Advanced Communications

A new, self-correcting crystal may just unleash a wave of next generation advanced communications. The nanostructured materials, a family of multilayered crystalline sandwiches, may just enable a new class of high-performance, high-efficiency components for devices such as cellular phones.

The new multilayer crystals are called "tunable dielectrics," the heart of electronic devices that enable cell phones to tune to a precise frequency, picking a unique signal out of the welter of possible ones. Tunable dielectrics that work well in the microwave range and beyond, though, have been difficult to make. Yet these new materials work well up to 100 GHz, which opens the door for the next generation of devices to advanced communications.

"People have created tunable microwave dielectrics for decades, but they've always used up way too much power," said Nathan Orloff, one of the researchers, in a news release.

Modern cellphone dielectrics use materials that suffer from misplaced or missing atoms called "defects" within their crystal structure. This interferes with the dielectric properties and can lead to power loss. The new materials, though, can self-correct.

"We refer to this material as having 'perfect faults,'" said Orloff in a news release. "When it's being grown, one portion accommodates defects without affecting the good parts of the crystal. It's able to correct itself and create perfect dielectric bricks that result in the rare combination of high tuning and low loss."

The new material is composed of layers of strontium oxide separating a variable number of layers of strontium titanate. On its own, strontium titanate is normally a pretty stable dielectric--not really tunable at all--but another bit of nanostructure working solves that. The sandwich layers of the material are grown as a thin crystalline film on top of a substrate material with a mismatched crystal spacing that produces strain within the strontium titanate structure that makes it a material that can be tuned.

"We were able to characterize the performance of these materials as a function of frequency running from 10 hertz all the way up to 125 gigahertz," said Orloff. "That's the equivalent of measuring wavelengths from kilometers down to microns all with the same experimental set-up. This material has a much lower loss and a much higher tenability for a given applied filed than any material that we have seen."

The details of the new material are published in the journal Nature.