Discovery of hardest known oxide

Léger, Jean‐Michel; Haines, J.; Schmidt, Max W.; Petitet, Jean Pierre; Pereira, Altaïr Soria; Jornada, J. A. H. da

doi:10.1038/383401a0

Cited by 175 publications

(90 citation statements)

References 9 publications

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“…Later the same modification was synthesized by shock wave [2] and detonation [3] methods. The determined bulk modulus of c-Si 3 N 4 was about 300 GPa and the hardness exceeded 35 GPa [4] which is slightly higher than for SiO 2 -stishovite (about 33 GPa) [5] often referred to as the third hardest material after diamond and cubic boron nitride [4,5].…”

Section: Introductionmentioning

confidence: 86%

Porous silicon nitride under shock compression

Yakushev¹,

Уткин²,

Zhukov³

2012

AIP Conference Proceedings

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Abstract. The measurements of the Hugoniot and sound velocity pressure dependence in β-Si 3 N 4 porous samples under shock loading up to 55 GPa are presented. The Hugoniot and experimental particle velocity profiles demonstrate no peculiarities arising from the phase transition into high density c-Si 3 N 4 . Nevertheless, it follows from the comparison of measured Hugoniot with the Hugoniot for monolithic samples that phase transition does take place, starting at a much lower pressure of approximately 25 GPa, where the two Hugoniots intersect. The analysis of the positional relationship of the Hugoniots for monolithic and porous samples allowed us to confirm that the transformation pressure threshold decreases with the temperature increase due to a greater heating of porous material under loading. Measurements of sound velocity in shocked samples showed that sound velocity pressure dependence has a kink near 23 GPa, which is very close to the presumable pressure of the transition to c-Si 3 N 4 in porous samples.

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Section: Introductionmentioning

confidence: 86%

Porous silicon nitride under shock compression

Yakushev¹,

Уткин²,

Zhukov³

2012

AIP Conference Proceedings

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“…This material is harder than stishovite and boron oxide and much harder than alumina 3,10 . Polycrystalline cubic boron nitride and sintered diamond are approximately two-times softer than their corresponding single crystal equivalents 3,7 . This suggests that the cotunnite-type TiO 2 is among the hardest known polycrystalline materials.…”

mentioning

confidence: 93%

“…It has been recognized that the hardness of ionic and covalent materials is related to elastic properties and increases with bulk modulus (K T ) and shear modulus (G) 1,5,[7][8][9] ( Table 1). A number of experimental and theoretical studies [10][11] indicate that titanium dioxide could have a series of high-pressure phases with hardness possibly approaching that of diamond.…”

mentioning

confidence: 99%

The hardest known oxide

Dubrovinsky

Dubrovinskaia

Swamy

et al. 2001

Nature

322

237

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“…3͒. Cubic RuO 2 is thus among the hardest oxides, but it is not superhard and it is significantly less hard than stishovite (SiO 2 ), 17 which is the hardest oxide known with H ϭ33 GPa. The bulk modulus of cubic RuO 2 does not scale well with the measured hardness of this material and is very high with respect to the shear modulus.…”

mentioning

confidence: 99%