High-pressure behavior of a<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Si</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>clathrate observed by using various pressure media

Yagi, T.; Iida, Etsuko; Hirai, Hisako; Miyajima, Nobuyoshi; Kikegawa, Takumi; Bunno, Michiaki

doi:10.1103/physrevb.75.174115

Cited by 32 publications

(35 citation statements)

References 17 publications

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“…However, it should be used with caution. In fact, it is well known that gas atoms penetrate into microporous crystals (that is, crystals having larger voids with a diameter up to 20 Å), such as fullerenes 31 , zeolites 32 , and clathrates 33 , and affect their compression behaviour. Our results suggest the possibility that helium may cause (or may have caused) some problems also in experiments on ordinary materials with voids.…”

Section: Discussionmentioning

confidence: 99%

Helium penetrates into silica glass and reduces its compressibility

2011

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SiO 2 glass has a network structure with a significant amount of interstitial voids. Gas solubilities in silicates are expected to become small under high pressure due to compaction of voids. Here we show anomalous behaviour of SiO 2 glass in helium. Volume measurements clarify that SiO 2 glass is much less compressible than normal when compressed in helium, and the volume in helium at 10 GPa is close to the normal volume at 2 GPa. X-ray diffraction and Raman scattering measurements suggest that voids are prevented from contracting when compressed in helium because helium penetrates into them. The estimated helium solubility is very high and is between 1.0 and 2.3 mol per mole of SiO 2 glass at 10 GPa, which shows marked contrast with previous models. These results may have implications for discussions of the Earth's evolution as well as interpretations of various high-pressure experiments, and also lead to the creation of new materials.

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Section: Discussionmentioning

confidence: 99%

Helium penetrates into silica glass and reduces its compressibility

2011

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“…The formation of neon‐bearing network solids can give several insights into the properties of the empty and filled network states. For example, pore dimensions can be rigorously evaluated as a function of temperature from the decapsulation peak profiles of He and Ne, the thermodynamic stability may be increased as found in neon clathrate hydrates, and the mechanical properties of the filled and empty network states can be drastically different, as known with other inclusion species . A combination of structural and computational investigations on the neon‐bearing network solids can provide fundamental information on neon‐neon and neon‐network interactions, which may be used towards synthesis strategies that aim to stabilise exotic chemically‐bound neon compounds as known with the heavier noble gases …”

Section: Figurementioning

confidence: 99%

Neon‐Bearing Ammonium Metal Formates: Formation and Behaviour under Pressure

et al. 2016

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The incorporation of noble gas atoms, in particular neon, into the pores of network structures is very challenging due to the weak interactions they experience with the network solid. Using high-pressure single-crystal X-ray diffraction, we demonstrate that neon atoms enter into the extended network of ammonium metal formates, thus forming compounds Ne [NH ][M(HCOO) ]. This phenomenon modifies the compressional and structural behaviours of the ammonium metal formates under pressure. The neon atoms can be clearly localised within the centre of [M(HCOO) ] cages and the total saturation of this site is achieved after ∼1.5 GPa. We find that by using argon as the pressure-transmitting medium, the inclusion inside [NH ][M(HCOO) ] is inhibited due to the larger size of the argon. This study illustrates the size selectivity of [NH ][M(HCOO) ] compounds between neon and argon insertion under pressure, and the effect of inclusion on the high-pressure behaviour of neon-bearing ammonium metal formates.

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“…It is interesting to note that the volume expands very fast with increasing temperature and then saturates at around 700 K, which is typical of the α-β transition such as that in quartz and cristobalite. 10,[15][16][17][18][19][20][21][22] The experimental studies have found the low-temperature phase as tetragonal for guest-bearing melanophlogite, whereas a lower symmetry (probably, an orthorhombic phase) was reported for guestfree melanophlogite. 3), which is also in agreement with experiments.…”

Section: A Temperature-induced Symmetrizationmentioning

confidence: 99%

“…10,[15][16][17][18][19][20][21][22] The experimental studies have found the low-temperature phase as tetragonal for guest-bearing melanophlogite, whereas a lower symmetry (probably, an orthorhombic phase) was reported for guestfree melanophlogite. 10,[15][16][17][18][19][20][21][22] However, such small differences (e.g., 0.1 o in angles or 0.3% in lengths at 300 K) can hardly be resolved by x-ray diffraction patterns as discussed in Ref. 3).…”

Section: A Temperature-induced Symmetrizationmentioning

confidence: 99%

“…Therefore we have studied the highpressure behavior of a SiO 2 clathrate called melanophlogite, which is an aluminum-free prototype of zeolite, 9-25 by using molecular dynamics simulations. 9,10,12,[18][19][20][21][22] In the past, many studies have been performed in order to understand the guest molecules trapped in the clathrates 23,24 and the role of the guest for the response of the host framework to pressure. Melanophlogite (type I SiO 2 clathrate) is a rare mineral first described by Lasulx in 1876, 11 known from only five volcanic areas.…”

Section: Introductionmentioning

confidence: 99%

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Structural properties and phase transitions in a silica clathrate

Liang

Ogundare

Miranda

et al. 2011

The Journal of Chemical Physics

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Melanophlogite, a low-pressure silica polymorph, has been extensively studied at different temperatures and pressures by molecular dynamics simulations. While the high-temperature form is confirmed as cubic, the low-temperature phase is found to be slightly distorted, in agreement with experiments. With increasing pressure, the crystalline character is gradually lost. At 8 GPa, the radial distribution function is consistent with an amorphous state. Like pristine glass, the topology changes, plastic behavior, and permanent densification appear above ∼12 GPa, triggered by Si coordination number changes. We predict that a partial crystalline and amorphous sample can be obtained by recovering the sample from a pressure of ∼12-16 GPa.

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High-pressure behavior of aSiO2clathrate observed by using various pressure media

Cited by 32 publications

References 17 publications

Helium penetrates into silica glass and reduces its compressibility

Helium penetrates into silica glass and reduces its compressibility

Neon‐Bearing Ammonium Metal Formates: Formation and Behaviour under Pressure

Structural properties and phase transitions in a silica clathrate

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