Hardness of nano- and microcrystalline lonsdaleite

Xingshuo Huang; Alan Salek; Andrew G. Tomkins; Colin M. Macrae; Nicholas C. Wilson; Dougal G. McCulloch; Jodie E. Bradby

doi:10.1063/5.0138911

Hardness of nano- and microcrystalline lonsdaleite

Xingshuo Huang^*, Alan Salek, Andrew G. Tomkins, Colin M. Macrae, Nicholas C. Wilson, Dougal G. McCulloch, Jodie E. Bradby

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

2 Citations (Scopus)

Abstract

Lonsdaleite is a hexagonal allotrope of carbon found in nature in meteorites and at meteorite impact sites. It has been predicted to have an indentation hardness greater than cubic diamond by first principles calculations. However, this has not been demonstrated experimentally. Here, nanoindentation was used to measure the hardness of two different lonsdaleite samples. One contains nanocrystalline lonsdaleite synthesized by high pressure compression of glassy carbon. The other is from a ureilite meteorite that contains lonsdaleite crystals up to ∼1 μm. The hardness of these two samples was determined using both the Oliver-Pharr and Meyer methods. Our results show that the hardness of the lonsdaleite samples is similar to that of diamond; therefore, there is no evidence that these forms of polycrystalline lonsdaleite are significantly harder than similar forms of diamond.

Original language	English
Article number	081902
Journal	Applied Physics Letters
Volume	122
Issue number	8
DOIs	https://doi.org/10.1063/5.0138911
Publication status	Published - 20 Feb 2023

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title = "Hardness of nano- and microcrystalline lonsdaleite",

abstract = "Lonsdaleite is a hexagonal allotrope of carbon found in nature in meteorites and at meteorite impact sites. It has been predicted to have an indentation hardness greater than cubic diamond by first principles calculations. However, this has not been demonstrated experimentally. Here, nanoindentation was used to measure the hardness of two different lonsdaleite samples. One contains nanocrystalline lonsdaleite synthesized by high pressure compression of glassy carbon. The other is from a ureilite meteorite that contains lonsdaleite crystals up to ∼1 μm. The hardness of these two samples was determined using both the Oliver-Pharr and Meyer methods. Our results show that the hardness of the lonsdaleite samples is similar to that of diamond; therefore, there is no evidence that these forms of polycrystalline lonsdaleite are significantly harder than similar forms of diamond.",

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AU - Huang, Xingshuo

AU - Salek, Alan

AU - Tomkins, Andrew G.

AU - Macrae, Colin M.

AU - Wilson, Nicholas C.

AU - McCulloch, Dougal G.

AU - Bradby, Jodie E.

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AB - Lonsdaleite is a hexagonal allotrope of carbon found in nature in meteorites and at meteorite impact sites. It has been predicted to have an indentation hardness greater than cubic diamond by first principles calculations. However, this has not been demonstrated experimentally. Here, nanoindentation was used to measure the hardness of two different lonsdaleite samples. One contains nanocrystalline lonsdaleite synthesized by high pressure compression of glassy carbon. The other is from a ureilite meteorite that contains lonsdaleite crystals up to ∼1 μm. The hardness of these two samples was determined using both the Oliver-Pharr and Meyer methods. Our results show that the hardness of the lonsdaleite samples is similar to that of diamond; therefore, there is no evidence that these forms of polycrystalline lonsdaleite are significantly harder than similar forms of diamond.

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Hardness of nano- and microcrystalline lonsdaleite

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