Hybrid nanoparticles have diamonds on the inside

Researchers have discovered a cheap way to construct nanomaterials using one of the least inexpensive products in the world: diamonds. A team from the University of Maryland (UMD) has developed a method to build diamond-based hybrid nanoparticles in large quantities — a leap which could have a positive impact on the energy efficiency of electronics and the speed of computer chips.

They used tiny, nanoscale diamonds containing a specific type of impurity: a single nitrogen atom where a carbon atom should be, with an empty space next to it, resulting from a second missing carbon atom. This ‘nitrogen vacancy’ impurity gives each diamond special optical and electromagnetic properties.

By attaching other materials to the diamond grains, such as metal particles or semiconducting materials known as ‘quantum dots’, the researchers can create a variety of customisable hybrid nanoparticles, including nanoscale semiconductors and magnets with precisely tailored properties.

“If you pair one of these diamonds with silver or gold nanoparticles, the metal can enhance the nanodiamond’s optical properties. If you couple the nanodiamond to a semiconducting quantum dot, the hybrid particle can transfer energy more efficiently,” said Min Ouyang, an associate professor of physics at UMD and senior author on the study.

Evidence also suggests that a single nitrogen vacancy exhibits quantum physical properties and could behave as a quantum bit, or qubit, at room temperature, according to Ouyang. Qubits are the functional units of as-yet-elusive quantum computing technology, which may one day revolutionise the way humans store and process information. Nearly all qubits studied to date require ultracold temperatures to function properly.

A qubit that works at room temperature would represent a significant step forward, facilitating the integration of quantum circuits into industrial, commercial and consumer-level electronics. The new diamond-hybrid nanomaterials described in Nature Communications hold significant promise for enhancing the performance of nitrogen vacancies when used as qubits, Ouyang noted.

While such applications hold promise for the future, Ouyang and colleagues’ main breakthrough is their method for constructing the hybrid nanoparticles. Although other researchers have paired nanodiamonds with complementary nanoparticles, such efforts relied on relatively imprecise methods, such as manually installing the diamonds and particles next to each other onto a larger surface one by one. These methods are costly, time-consuming and introduce a host of complications, the researchers say.

“Our key innovation is that we can now reliably and efficiently produce these freestanding hybrid particles in large numbers,” explained Ouyang.

The method developed by Ouyang and his colleagues, UMD physics research associate Jianxiao Gong and physics graduate student Nathaniel Steinsultz, also enables precise control of the particles’ properties, such as the composition and total number of non-diamond particles. The hybrid nanoparticles could speed the design of room-temperature qubits for quantum computers, brighter dyes for biomedical imaging, and highly sensitive magnetic and temperature sensors, to name a few examples.

“Hybrid materials often have unique properties that arise from interactions between the different components of the hybrid. This is particularly true in nanostructured materials where strong quantum mechanical interactions can occur,” said Matthew Doty, an associate professor of materials science and engineering at the University of Delaware who was not involved with the study.

“The UMD team’s new method creates a unique opportunity for bulk production of tailored hybrid materials. I expect that this advance will enable a number of new approaches for sensing and diagnostic technologies.”

The paper, as published in Nature Communications, is available in full from www.nature.com.