New materials from high-pressure experiments

McMillan, Paul F.

doi:10.1038/nmat716

Cited by 507 publications

(328 citation statements)

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“…These studies have enhanced our understanding of chemical bonds under compression and provide opportunities to seek additional novel materials; however, it has been difficult to retain these remarkable structures at the ambient conditions needed for most applications (9). For CO 2 , a 3D covalent network was synthesized (3) at high pressure (40 GPa) and temperature (1,800 K) that is isomorphic to the β-cristobalite phase of SiO 2 (10), with each carbon atom bonded tetrahedrally to four oxygen atoms.…”

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confidence: 99%

Formation of the –N(NO)N(NO)– polymer at high pressure and stabilization at ambient conditions

Xiao

Goddard

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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A number of exotic structures have been formed through highpressure chemistry, but applications have been hindered by difficulties in recovering the high-pressure phase to ambient conditions (i.e., one atmosphere and 300 K). Here we use dispersion-corrected density functional theory [PBE-ulg (Perdew-Burke-Ernzerhof flavor of DFT with the universal low gradient correction for long range London dispersion)] to predict that above 60 gigapascal (GPa) the most stable form of N 2 O (the laughing gas in its molecular form) is a one-dimensional polymer with an all-nitrogen backbone analogous to cis-polyacetylene in which alternate N are bonded (ionic covalent) to O. The analogous trans-polymer is only 0.03∼0.10 eV/ molecular unit less stable. Upon relaxation to ambient conditions, both polymers relax below 14 GPa to the same stable nonplanar trans-polymer. The predicted phonon spectrum and dissociation kinetics validates the stability of this trans-poly-NNO at ambient conditions, which has potential applications as a type of conducting nonlinear optical polymer with all-nitrogen chains and as a highenergy oxidizer for rocket propulsion. This work illustrates in silico materials discovery particularly in the realm of extreme conditions (very high pressure or temperature).DFT | high pressure physics and chemistry | prediction of novel materials W ith strong interplay between experiment and theory, such molecular crystals as N 2 (1, 2), CO 2 (3, 4), CO (5, 6), NH 3 (7), and benzene (8) have been transformed into extended solids (covalent and ionic bonded networks) under high pressures. These studies have enhanced our understanding of chemical bonds under compression and provide opportunities to seek additional novel materials; however, it has been difficult to retain these remarkable structures at the ambient conditions needed for most applications (9). For CO 2 , a 3D covalent network was synthesized (3) at high pressure (40 GPa) and temperature (1,800 K) that is isomorphic to the β-cristobalite phase of SiO 2 (10), with each carbon atom bonded tetrahedrally to four oxygen atoms. This phase of CO 2 was proposed to have potential applications as superhard (initial experiments estimated a bulk modulus of 365 GPa (11), but theory and experiment later found it to be 136 GPa (10, 12)), nonlinear optical, and high-energy density material, so efforts were made to quench this phase down to 1 atm and 300 K (3); however, it reverts back to the molecular phase at pressures lower than 1 GPa.Because it is isoelectronic to CO 2 but polar, attempts were made to form an extended solid from N 2 O using compression (above 20 GPa) and laser heating (above 1,000 K) in a diamond anvil (13). However, instead it decomposed into a mixture of an ionic crystal NO + NO 3 − and compressed N 2 molecules. No covalent extended framework similar to the polymeric CO 2 phase was found. Indeed, because the nitrogen atom forms one less covalent bond than the carbon atom, it is not obvious that it would be possible to construct a dense extended solid phase o...

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confidence: 99%

Formation of the –N(NO)N(NO)– polymer at high pressure and stabilization at ambient conditions

Xiao

Goddard

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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“…[1][2][3] The orthorhombic borides, formulated as XYB 14 where X and Y are metal atoms, have been of interest to scientists and engineers for the past decade due to a report [4,5] that AlMgB 14 prepared by mechanical milling can achieve a hardness between 32 and 46 GPa. The reason for the observed superhardness is not understood.…”

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confidence: 99%

Fracture Strength ofAlLiB14

Wan

Beckman

2012

Phys. Rev. Lett.

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“…CO is one of the most extensively studied molecular crystals [3][4][5][6][7][8][9][10][11][12]. Studies of polymerization of CO are motivated by the desire to understand the fundamental physics and chemistry of geological and planetary processes, where CO is present, and to search for new materials [13] exhibiting properties such as ''high energy density'' [10] and ''superhardness'' [14,15].…”

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confidence: 99%