[HN Gopher] Material made of carbon and nitrogen is nearly as ha...
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Material made of carbon and nitrogen is nearly as hard as diamond
Author : simonebrunozzi
Score : 16 points
Date : 2023-12-24 17:06 UTC (5 hours ago)
(HTM) web link (www.newscientist.com)
(TXT) w3m dump (www.newscientist.com)
| bell-cot wrote:
| > An elusive material that scientists have wanted to make for
| decades has finally been synthesised under tremendous heat and
| pressure...
|
| > The samples are just 5 micrometres across and 3 micrometres
| deep, and scaling-up production could be difficult...
|
| > ... much more expensive than diamond to buy. But Laniel says
| the material has benefits that diamond doesn't, such as
| generating an electrical signal under pressure, which could make
| it useful in sensors. Its high energy density could also make it
| a powerful explosive...
|
| Far more expensive than diamond, not as hard, and it's explosive
| to boot. I'm not seeing much reason to scale up production.
| contingencies wrote:
| 1. Lighter perhaps?
|
| 2. Useful as a pressure sensor in high force assemblies.
| aifooh7Keew6xoo wrote:
| I assume this is discussing
| https://en.wikipedia.org/wiki/%CE%92-Carbon_nitride but the
| article neglects to identify the carbon nitride compound and the
| journal article doesn't seem to be available.
| hinkley wrote:
| I was reacquainted with Titanium Nitride care of a woodworker
| on YouTube the other day. It's being used to protect tool
| surfaces from wear. Is that a coincidence or is there something
| special about nitrogen as a dopant?
| aifooh7Keew6xoo wrote:
| https://en.wikipedia.org/wiki/Nitride
|
| > Like carbides, nitrides are often refractory materials
| owing to their high lattice energy, which reflects the strong
| bonding of "N3-" to with metal cation(s). Thus, cubic boron
| nitride, titanium nitride, and silicon nitride are used as
| cutting materials and hard coatings. Hexagonal boron nitride,
| which adopts a layered structure, is a useful high-
| temperature lubricant akin to molybdenum disulfide.
|
| Beyond that, when it comes to cutting tools in particular,
| there's often interesting solid phase and surface chemistry
| with layered gradients of oxynitrides forming at depth from
| the working interface that have similar properties to the
| base nitride and absorb energy through multiple phase changes
| and chemical dissociations before ultimate mass reduction,
| extending the life of the working surface
| BobaFloutist wrote:
| I mean diamond is pure carbon, so if anything the nitrogen is
| making the substance in the article weaker.
| Someone wrote:
| > making the substance in the article weaker.
|
| Less hard, to be more precise [1]. "Strong" and "weak" are
| way imprecise terms in engineering.
|
| The simplest example is whether it's strong under pressure
| (a brick is, a rope isn't) or under tension (a rope is, a
| brick isn't), but there are tons of other properties that
| are an indicator of strength of a material
| (https://en.wikipedia.org/wiki/Strength_of_materials), and
| this may beat diamond in some of them.
|
| Reading https://en.wikipedia.org/wiki/Material_properties_o
| f_diamond, diamond isn't particularly tough, and we don't
| really know its tensile strength, so this is less hard, but
| may have higher toughness or higher tensile strength.
|
| [1] reading Wikipedia, even that isn't simple: _"There are
| three main types of hardness measurements: scratch,
| indentation, and rebound. Within each of these classes of
| measurement there are individual measurement scales. For
| practical reasons conversion tables are used to convert
| between one scale and another."_
| ThrowawayR2 wrote:
| The paper is available if you do a bit of digging. Following
| the name of the principal investigator goes to his site. The
| paper is not in his list of publications (one would think an
| academic would be a stickler about updating that?) but the news
| link leads to the institution's news story about that
| research1. It's worth a read since it's more detailed than the
| New Scientist article without being as dense as the paper
| itself. At the bottom of the institution's news story is a link
| to the paper2 which is freely available.
|
| So if anyone is wondering what the "more chemically accurate
| name would be a mouthful refers to" (oP8-CN, tI14-C3N4,
| hP126-C3N4, and tI24-CN2 were the carbon nitride forms
| produced) or what the "powerful explosive" mention refers to ("
| _Energy density calculations were performed for the four C-N
| compounds with respect to decomposition into graphite and
| molecular nitrogen, at ambient conditions. They revealed that
| they have a high gravimetric energy density, comparable to or
| higher than that of TNT for oP8-CN, tI14-C3N4, hP126-C3N4,and
| for tI24-CN2, a value even higher than for RDX..._ "), it's all
| there.
|
| 1 https://www.ph.ed.ac.uk/news/2023/breakthrough-in-
| synthesis-...
|
| 2
| https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202308...
| exabrial wrote:
| > It could potentially be used in cutting tools... and even as an
| explosive
|
| Nice! Would make for a exciting day on the milling machine
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