All Research

Synthesis of bulk hexagonal diamond

NatureNature·
Read the paperDOI: 10.1038/s41586-025-09343-x

TL;DR

You know how carbon can be arranged in different ways — like graphite in your pencil or diamonds in jewelry? Scientists have long suspected there's a third arrangement of carbon atoms, shaped like hexagons instead of cubes, that might be even harder than regular diamond. The problem was nobody could make a piece big enough to actually study. This team took ultra-pure graphite crystals, squeezed and heated them under very carefully controlled conditions, and finally grew chunks of this hexagonal diamond big enough to see, hold, and test. Think of it like finally baking a cake you've only ever seen in a recipe book for 60 years — and discovering it tastes almost exactly like the cake you already knew, but slightly better.

Hexagonal diamond (HD), with anticipated physical properties superior than the known cubic diamond, has been pursued relentlessly since its inception 60 years ago. However, natural and synthetic HD has only been preserved as a highly disordered component in fragile, heterogeneous mixtures of other nanocarbon structures that precludes determination of bulk properties and identification of HD as a bona fide crystalline phase. Here we report the synthesis, recovery and extensive characterization of bulk HD by compressing and heating high-quality graphite single crystals under controlled quasi-hydrostatic conditions. We demonstrate the successful synthesis of 100-um-sized to mm-sized, highly ordered, bulk HD. We observed direct transformation of graphite (1010) orientation to HD (0002) and graphite (0002) to HD (1010). The bulk sample consists of threefold intergrowth of tightly knitted 100-nm-sized crystals, predominantly HD with trace imperfections of cubic diamond. The interlayer bonds in HD are shortened with respect to intralayer bonds to optimize the HD structure. Notably, the hardness of HD is only slightly higher than cubic diamond. We anticipate that purifying the precursor graphite carbon and fine-tuning the high pressure-temperature (P-T) synthesis conditions may lead to higher-quality HDs.

  • 1Successfully synthesized 100-micrometer to millimeter-sized bulk hexagonal diamond (HD) by compressing and heating high-quality graphite single crystals under controlled quasi-hydrostatic conditions
  • 2Demonstrated direct crystallographic transformation of graphite (1010) to HD (0002) and graphite (0002) to HD (1010), establishing an epitaxial relationship
  • 3Revealed that bulk HD consists of threefold intergrowth of 100-nm-sized crystals, predominantly HD with trace cubic diamond imperfections
  • 4Determined that interlayer bonds in HD are shortened relative to intralayer bonds, revealing the optimized structural configuration of HD
  • 5Measured that the hardness of bulk HD is only slightly higher than cubic diamond, providing the first reliable bulk mechanical property data for HD
Nature·

Over 20,000 precolonial earthworks in the Southwest Amazonia

Imagine flying a special laser scanner over the Amazon jungle that can 'see through' the treetops, like X-ray vision for the ground. When scientists did this, they found over 20,000 geometric shapes — ditches, mounds, and enclosures — built by ancient people long before Europeans arrived. These aren't small things: they're massive earthen structures, like monuments. This means the Amazon rainforest, which most people picture as empty wilderness, was actually home to millions of people who built cities and shaped the landscape. Think of it like discovering that a forest you thought was wild was actually someone's ancient garden on a continental scale.

Nature·

A digitally controlled silicon quantum processing unit

Imagine you want to build a super-powerful calculator that uses the weird rules of quantum physics to solve problems no regular computer can. The trouble is, the tiny quantum pieces — called qubits — are incredibly fragile and need to be kept colder than outer space. On top of that, you need wires and control signals going to every single qubit, and if you have thousands of them, the wiring becomes a nightmare. This team solved part of that puzzle by building their qubits out of silicon (the same stuff in your phone's chip), adding a tiny control computer that works at super-cold temperatures right next to the qubits, and using a special high-density cable to connect everything cleanly. They packed 54 tiny quantum dots onto a chip, arranged 18 of them into working qubits, and showed the qubits work about 10 times better than any previous silicon qubit of this type. They also ran basic error-correction experiments to prove the system is on track for real-world use.

Scientific American·

The 2026 World Cup's grass is an engineering problem

Imagine you're trying to play soccer in 16 different places across the United States, Canada, and Mexico — some in freezing cold, some blazing hot, some in stadiums with roofs that block sunlight. Half of those stadiums normally use fake grass. Now FIFA, the organization that runs the World Cup, wants every single pitch to feel and play exactly the same way, like a video game where every level has identical physics. To do that, they hired grass scientists — yes, that's a real job — who figured out how to grow special grass on thin mats with plastic underneath so it can be transported like a carpet, stitched with synthetic fibers so it doesn't rip when players sprint and tackle, and tested by literally shooting balls at it with a cannon to make sure it bounces right. Different grass species are used depending on whether a stadium is hot, cool, or dark. It's basically a giant, living, high-tech floor installation that has to survive the world's best athletes running on it.

Monthly Notices of the Royal Astronomical Society·

Remarks on the disproof of the unit distance conjecture

Imagine you scatter a bunch of dots on a piece of paper. The question is: how many pairs of those dots can be exactly 1 inch apart? The Erdős unit distance conjecture asked whether there's a specific mathematical formula that limits how often this can happen as you add more and more dots. Think of it like asking how many friendships can exist in a town where friends are defined as people who live exactly one mile apart — there's a suspected maximum, and Erdős guessed what that maximum should be. For decades, no one could prove or disprove his guess. Now, an AI apparently found a specific arrangement of dots (a 'counterexample') that breaks the expected limit, proving Erdős's conjecture was wrong. A team of elite mathematicians then checked and explained the AI's work in this paper.