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
Science News

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Scientific American·

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Nature Genetics·

Non-Mendelian inheritance of DNA methylation patterns in mice

Imagine your DNA is like a huge book of instructions. Mendel's laws are the normal rules for how chapters of that book get passed from parents to children. But there's also a layer of sticky notes on top of the book—called epigenetic marks—that tell cells which chapters to read and which to ignore. This study found that most of the time (about 93%), these sticky notes follow the normal inheritance rules. But about 7% of the time, they do something unexpected: new patterns appear that neither parent had, or a mark from one parent somehow silences the same mark from the other parent (called paramutation), or males and females end up with completely different sticky notes even when they inherit the same DNA. Scientists discovered this by using a new ultra-precise DNA reading technology in mice, and it opens the door to understanding hidden layers of how traits—and possibly diseases—are passed down through generations.

New England Journal of Medicine·

Digital twin–guided ablation for ventricular tachycardia

Imagine your heart is a city, and ventricular tachycardia is like a traffic jam caused by a broken road — electrical signals get stuck going in circles instead of flowing properly, causing the heart to beat dangerously fast. Doctors can fix this by burning away the broken road using a procedure called ablation. The problem is, finding the exact broken road inside a beating heart is like navigating a city you've never visited before, while driving, in the dark. What these researchers did is take detailed MRI pictures of each patient's heart, build a 3D computer copy — a 'digital twin' — and then simulate where the electrical problem was happening inside that virtual heart. They tested their fix on the computer model first, figured out exactly where to go, and THEN performed the real procedure. What used to take three hours of exploratory surgery was done in about 30 minutes, because the doctors already had a GPS map before they started.