Metallization of magnesium polyhydrides under pressure

Lonie, David; Hooper, James; Altıntaş, Bahadır; Zurek, Eva

doi:10.1103/physrevb.87.054107

Cited by 128 publications

(147 citation statements)

References 65 publications

(87 reference statements)

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“…This structure was optimized with fully relaxing the atoms and lattice parameters within firstprinciples electronic structure framework, which produces a body centered cubic (bcc) crystal structure and space group of Im-3m with 14 atoms per unit cell, in agreement with our previous work. 1), where previously predicted P6 3 /mmc Ni 2 In-type structure 21 was used for MgH 2 and C2/c and Cmca-12 structure 22 were used for solid hydrogen. 1), where previously predicted P6 3 /mmc Ni 2 In-type structure 21 was used for MgH 2 and C2/c and Cmca-12 structure 22 were used for solid hydrogen.…”

Section: Resultsmentioning

confidence: 99%

“…[11][12][13][14][15][16][17][18] At present, the superconducting mechanism of compressed H 2 S is not quite clear and remains elusive. 21 In this work, we study the stability of MgH 6 relative to MgH 2 and H 2 on the basis of first-principle density functional theory. Recently, CaH 6 has been predicted to have a good superconductivity of 235 K at 150 GPa.…”

Section: Introductionmentioning

confidence: 99%

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Compressed sodalite-like MgH₆ as a potential high-temperature superconductor

et al. 2015

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Recently, an experimental work reported a very high Tc of ~190K in hydrogen sulphide (H2S) at 200 GPa. The search of new superconductors with high superconducting critical temperatures in hydrogen-dominated materials has attracted significant attention. Here we predict a candidate phase of MgH6 with a sodalite-like framework in conjunction with firstprinciples electronic structure calculations. The calculated formation enthalpy suggests that it is thermodynamically stable above 263 GPa relative to MgH2 and solid hydrogen (H2). Moreover, the absence of imaginary frequency in phonon calculations implies that this MgH6 structure is dynamically stable. Furthermore, our electron-phonon coupling calculation based on BCS theory indicates that this MgH6 phase is a conventional superconductor with a high superconducting critical temperature of ~260 K under high pressure, which is even higher than that of the recently reported compressed H2S. The present results offer insights in understanding and designing new high-temperature superconductors.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Compressed sodalite-like MgH₆ as a potential high-temperature superconductor

et al. 2015

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“…Therefore, building on Ashcroft's proposals, density functional theory (DFT) calculations were carried out to predict the structures of hydrides with stoichiometries that are not stable at atmospheric conditions, in the hopes of uncovering hitherto unknown superconductors [19]. Since then, numerous theoretical studies have been performed that investigate the phase diagrams of hydrogen doped with the electropositive alkali metals or alkaline earth metals [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34], as well as the electronegative element iodine [35,36] under pressure. Experimental work on the hydrides of lithium and sodium confirmed that species with unique stoichiometries such as NaH 3 and NaH 7 can be synthesized in diamond anvil cells, but the phases that have been reported to date do not exhibit superconductivity [21,37].…”

Section: Introductionmentioning

confidence: 99%

Superconductivity in Hydrides Doped with Main Group Elements Under Pressure

Shamp¹,

Zurek²

2017

Novel Superconducting Materials

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A priori crystal structure prediction techniques have been used to explore the phase diagrams of hydrides of main group elements under pressure. A number of novel phases with the chemical formulas MHn, n > 1 and M = Li, Na, K, Rb, Cs; MHn, n > 2 and M= Mg, Ca, Sr, Ba; HnI with n > 1 and PH, PH 2 , PH 3 have been predicted to be stable at pressures achievable in diamond anvil cells. The hydrogenic lattices within these phases display a number of structural motifs including H δ− 2 , H − , H − 3 , as well as one-dimensional and three-dimensional extended structures. A wide range of superconducting critical temperatures, Tcs, are predicted for these hydrides. The mechanism of metallization and the propensity for superconductivity are dependent upon the structural motifs present in these phases, and in particular on their hydrogenic sublattices. Phases that are thermodynamically unstable, but dynamically stable, are accessible experimentally. The observed trends provide insight on how to design hydrides that are superconducting at high temperatures.

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“…New polyhydride phases are also anticipated for alkaline earth metals [24,72,73]. The theoretically predicted polyhydrides are not only stabilized by compression, but are expected to metalize and exhibit superconducting properties at lower pressures than the constituent parts -the monohydride and hydrogen.…”

Section: Polyhydrides Of Alkali and Alkaline Earth Metalsmentioning

confidence: 91%

Superconductivity in compressed hydrogen-rich materials: Pressing on hydrogen

Struzhkin

2015

Physica C: Superconductivity and its Applications

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a b s t r a c tPeriodic table of elements starts with hydrogen, a simplest element of all. The simplicity is lost when the element is compressed to high densities or participates in a chemical bonding in compounds, being subjected to ''chemical pressure'' of surrounding atoms or molecules. The chemical nature of hydrogen is dictated by its simplest electronic shell, which has only one electron. Hydrogen can donate this electron and behave like alkali metal, or accept an extra electron and form a hydride ion with closed shell resembling a group VII element. The complexity of hydrogen goes beyond these simplest configurations, when hydrogen is involved in a multicenter bonding or in hydrogen bonds. This complex behavior is tightly related to the ability of hydrogen to participate in the process of electronic transport in solids and potentially be able to contribute to the superconductivity in a material. Hydrogen by itself when compressed to immense pressures of 400-500 GPa may form a simple atomic phase with very high critical superconducting temperatures (T c ) well above room temperature. While this theoretical insight awaits confirmation at pressures at the limit of current experimental capabilities, a variety of other hydrogen-rich materials have been suggested recently to have record high T c values. The very existence of many of these materials still lacks experimental confirmation. In this review article, we will present an extensive list of such predicted materials. We will also review superconductivity in classical hydrides (mostly metal hydrides) and current theoretical understanding of relatively low T c 's in metal hydrides of transition and noble metals.

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Metallization of magnesium polyhydrides under pressure

Cited by 128 publications

References 65 publications

Compressed sodalite-like MgH₆ as a potential high-temperature superconductor

Compressed sodalite-like MgH₆ as a potential high-temperature superconductor

Superconductivity in Hydrides Doped with Main Group Elements Under Pressure

Superconductivity in compressed hydrogen-rich materials: Pressing on hydrogen

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Metallization of magnesium polyhydrides under pressure

Cited by 128 publications

References 65 publications

Compressed sodalite-like MgH6 as a potential high-temperature superconductor

Compressed sodalite-like MgH6 as a potential high-temperature superconductor

Superconductivity in Hydrides Doped with Main Group Elements Under Pressure

Superconductivity in compressed hydrogen-rich materials: Pressing on hydrogen

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Compressed sodalite-like MgH₆ as a potential high-temperature superconductor

Compressed sodalite-like MgH₆ as a potential high-temperature superconductor