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Abstract: We have measured the electrical resistance of (Mg0.9Fe0.1)SiO3 perovskite with increasing pressure in a diamond-anvil cell (DAC). Results demonstrate that the electrical conductivity increased with pressure to about 70GPa, then conversely decreased to around 85GPa, and again increased mildly to 135GPa. As inferred from the previous studies of (Mg,Fe)O ferropericlase, the observed reduction in the conductivity of perovskite at 70–85GPa is most likely due to the high-spin to low-spin transition of iron; it decreases the number of unpaired electrons and therefore diminishes the conduction by electron hopping between the ferric and ferrous iron sites. Present conductivity data provide valuable implications for the pressure range of spin transition in (Mg,Fe)SiO3 perovskite, which has been highly controversial. The relatively abrupt reduction in the electrical conductivity above 70GPa is reconciled with the spin-pairing transition in ferric iron, which may occur rather sharply at this pressure range. [Copyright &y& Elsevier]

The crystallographic structure of anthracene is studied under high pressure up to 27 GPa using diamond anvil cells. Different pressure-transmitting media (helium, a methanol–ethanol mixture, a normal- and iso-pentane mixture and no medium) were used up to specific critical pressures where the hydrostatic conditions are lost. It is clearly observed that the loss of hydrostaticity is associated with a crystallographic phase-transition in anthracene. The phase-transition is observed as reversible, and it is accompanied by a large hysteresis. These observations clarify conflicting reports in the literature on the high-pressure phase-transition of anthracene. [Copyright &y& Elsevier]

Abstract: X-ray powder diffraction study of PbHPO4 was carried out under hydrostatic conditions at room temperature. We could not detect any difference in the diffraction patterns except peak shift with increasing pressures up to 6GPa. By further compression, a new pressure-induced phase appears at about 6.5GPa. We have determined that the structure of this high-pressure phase has a possible space group of Pmmm, and which is stable up to 17GPa. During decompression process, this phase is converted back to the original phase II at 0.7GPa. [Copyright &y& Elsevier]

Here we report on the effects of material strength factors on the generation of surface structure due to nonuniform laser irradiation. The influence of material strength on the generation of perturbation on a diamond surface subjected to nonuniform laser irradiation was experimentally investigated. Our previous investigations suggested that stiffer and denser materials reduce surface perturbation due to spatially nonuniform laser irradiation, which was reproduced well by calculations with multi-dimensional hydrodynamic simulation code. In this work, we found that local fractures due to yield strength failure are generated by high degrees of irradiation non-uniformity. A characteristic crack-like surface structure was observed, which was not reproduced by the 2D simulation code calculations at all. The 2D simulations showed that the pressure at the diamond surface locally exceeds the Hugoniot elastic limit due to nonuniform irradiation, implying the potential for development of surface perturbations. We also measured the areal-density distribution of perturbations for single-crystal diamond and diamond with a thin high atomic number (high-Z) coating on its surface. The experimental results imply that the combination of a stiff material and thin high-Z coating can suppress the solid-strength effects caused by large irradiation non-uniformity. The knowledge given here is applicable to inertial confinement fusion target design, laser material processing, and universal problems involving solids and high-energy-density plasmas. [ABSTRACT FROM AUTHOR]

Both micro-paired and conical support type double-stage diamond anvil cells (ds-DAC) were tested using a newly synthesized ultra-fine nano-polycrystalline diamond (NPD). Well-focused X-ray sub-micron beam and the conically supported 2nd stage anvils (micro-anvils) with 10 μm culet enable us to obtain good quality X-ray diffraction peaks from the sample at around 400 GPa. The relationship between confining pressure and sample pressure depends heavily on the initial height (thickness) of micro-anvils, the difference of a few micrometers leads to a quite different compression path. The conical support type is a solution to retain both enough thickness and strength of micro-anvils at higher confining pressure conditions. All conical support ds-DAC experiments terminated by the failure of the 1st stage anvil instead of 2nd one. The combination of ultra-fine NPD 2nd stage anvil and NPD 1st stage anvil opens a new frontier for measurement of the X-ray absorption spectrum above 300 GPa. [ABSTRACT FROM AUTHOR]

Highlights • DDR-type zeolite membrane with excellent CO 2 permselectivity was successfully developed. • The membrane durability was confirmed by 140 hrs gas permeation testing up to 8 MPa G. • Importance of high CO 2 permselective membrane was indicated for a CO 2 -EOR project. Abstract JGC Corporation (JGC) and NGK Insulators, Ltd. (NGK) have been developing the world's largest DDR-type zeolite membrane to meet the practical needs of CO 2 /hydrocarbon separation in the natural gas and CO 2 Enhanced Oil Recovery (CO 2 -EOR) industries. DDR-type zeolite has desirable nano-size pores for CO 2 /hydrocarbon separation. NGK has developed a thin, defect-free DDR-type zeolite membrane with a monolithic structure. This membrane is prepared onto the inner surface of a cylindrical monolithic alumina substrate having 30 channels with a diameter and length of 30 mm and 160 mm, respectively. CO 2 permselectivity over CH 4 of the monolithic membrane was investigated using the binary gas mixture of 61–67 mol% CO 2 and 33–39 mol% CH 4 at 44–46 °C with up to 8.0 MPa G as the feed pressure. The CO 2 permeability reached 1973 Barrer (6.6 × 10−13 mol m m−2 s−1 Pa−1) while the separation factor of CO 2 /CH 4 exceeded 140 at the transmembrane pressure difference of 2.5 MPa. This CO 2 permeability decreased to 1154 Barrer (3.9 × 10−13 mol m m−2 s−1 Pa−1) at the transmembrane pressure difference of 7.0 MPa; however, the separation factor of CO 2 /CH 4 was still as high as 90. In order to understand the stability of the monolithic membrane, the change in the permeability of CO 2 and CH 4 with time was measured at 58–60 °C with transmembrane pressure difference of 7.4–7.7 MPa using the binary gas mixture of 65–71 mol% CO 2 and 29–35 mol% CH 4 for 140 h. During the gas permeation test, the CO 2 permeability was almost constant while CH 4 permeability slightly decreased. As a result, the separation factor of CO 2 /CH 4 was maintained at the initial value. Based on the experimental results, we evaluated the potential applicability of the DDR-type zeolite membrane compared to the conventional polymer membrane for a CO 2 recovery process in a CO 2 -EOR project where CO 2 is often separated from the associated gas for re-use. We assumed that the associated gas contains 70 mol% CO 2 and 30 mol% CH 4 at a pressure of 4.0 MPa G while the specification of CO 2 purity in the permeate gas was 95 mol% at a pressure of 0.3 MPa G. When this associated gas is treated using a single-stage membrane process, only 49% of CO 2 was recovered by a membrane having a CO 2 /CH 4 separation factor of 12.5 like a typical polymer membrane. On the other hand, membranes having CO 2 /CH 4 separation factors of 80–100 could recover 98–99% of CO 2 while more than 96 mol% purity of CH 4 was obtained at the retentate side. This simulation study indicated that the highly selective membrane like the DDR-type zeolite membrane can recover not only high purity CO 2 for CO 2 -EOR projects, but also make available CH 4 for use or sale. This high purity CH 4 brings additional benefit to the CO 2 -EOR operators. [ABSTRACT FROM AUTHOR]

Polyhydrides of alkali metals under high pressures have been attracting great interests owing to the predicted pressure-stabilized untraditional stoichiometries and potential superconductivity. We have performed Raman scattering measurements of lithium polyhydrides synthesized under high pressure and high temperature conditions up to 182 GPa. Between 30 and 180 GPa, four phases appear, and they are tentatively named α (30-140 GPa), β (30-90 GPa), γ (90-140 GPa), and δ (140 GPa) phase. By observing the H2 vibrons at higher wavenumbers than pure H2 and their pressure dependence, it was revealed that the α phase contains electrically neutral H2 in its crystal lattice without electron transfer from Li atoms. The comparisons with H2-containing rare gas compounds Ar(H2)2, Kr(H2)4, and Xe(H2)8 suggest that a H2 molecule is surrounded by six to eight neighboring H2 molecules in the α phase. On the other hand, the Raman spectra of the β, γ, and δ phases suggest that they contain the elongated H2 that is negatively charged by the electron transferred from the surrounding matrices. All the α, β, γ, and δ phases were found to remain transparent insulators at pressures below 182 GPa. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Metal intercalation to graphite produces various types of superconductors. The highest superconducting transition temperature T c (onset temperature, T c onset , of 11.5 K) was found in Ca intercalated graphite, denoted CaC 6 . T c onset increased up to 15.1 K at 7.5 GPa, implying a positive pressure dependence. However, no new metal-intercalated graphite superconductors with T c onset higher than 11.5 K at ambient pressure have so far been reported. To search for new graphite superconductors, we successfully synthesized binary-element-intercalated graphite, Ca x K 1−x C y . Their structure resembles that of KC 8 . T c increased continuously with increasing x. Furthermore, the pressure dependence of T c in Ca 0.6 K 0.4 C 8 was investigated over a wide pressure range from 0–43 GPa. T c (= 9.6 K at 0 GPa) increased to 11.6 K at 3.3 GPa, and decreased to 2.0 K at 41 GPa. This behavior is similar to that of CaC 6 , albeit with a lower maximum T c . X-ray diffraction patterns were measured under high pressures of 0–24 GPa, and suggest a structural transition at 15 GPa. Evidence is given for superconducting graphite involving binary metal intercalation. [ABSTRACT FROM AUTHOR]

We have studied the superconducting properties of CeTIn5 (T=Rh, Ir) under high pressures by means of electrical resistivity measurements and determined the pressure–temperature phase diagrams for the superconducting transition. For both systems, the superconductivity exists in a wide pressure range, 1.5⩽P⩽6.5 GPa for CeRhIn5 and 0⩽P⩽5.2 GPa for CeIrIn5. [Copyright &y& Elsevier]

‘Aromatic hydrocarbon’ implies an organic molecule that satisfies the (4 n + 2) π-electron rule and consists of benzene rings. Doping solid aromatic hydrocarbons with metals provides the superconductivity. The first discovery of such superconductivity was made for K-doped picene (K x picene, five benzene rings). Its superconducting transition temperatures ( T c ’s) were 7 and 18 K. Recently, we found a new superconducting K x picene phase with a T c as high as 14 K, so we now know that K x picene possesses multiple superconducting phases. Besides K x picene, we discovered new superconductors such as Rb x picene and Ca x picene. A most serious problem is that the shielding fraction is ⩽15% for K x picene and Rb x picene, and it is often ∼1% for other superconductors. Such low shielding fractions have made it difficult to determine the crystal structures of superconducting phases. Nevertheless, many research groups have expended a great deal of effort to make high quality hydrocarbon superconductors in the five years since the discovery of hydrocarbon superconductivity. At the present stage, superconductivity is observed in certain metal-doped aromatic hydrocarbons (picene, phenanthrene and dibenzopentacene), but the shielding fraction remains stubbornly low. The highest priority research area is to prepare aromatic superconductors with a high superconducting volume-fraction. Despite these difficulties, aromatic superconductivity is still a core research target and presents interesting and potentially breakthrough challenges, such as the positive pressure dependence of T c that is clearly observed in some phases of aromatic hydrocarbon superconductors, suggesting behavior not explained by the standard BCS picture of superconductivity. In this article, we describe the present status of this research field, and discuss its future prospects. [ABSTRACT FROM AUTHOR]

Effects of high pressure exceeding 10 GPa on spin-driven ferroelectricity were investigated for a multiferroic, triangular-lattice antiferromagnet (TLA), CuCrO2. For this purpose, we developed a system which enables us to measure ferroelectric polarization under a pressure of 10 GPa by using a diamond anvil cell. We found that the magnetic transition temperature accompanying the ferroelectric one in CuCrO2 was remarkably enhanced by applying pressure. The result is simply explained by considering the pressure-induced enhancement of inter- and/or intralayer magnetic interaction due to the compression of the lattice. In addition, the coercive electric field for the polarization reversal was also increased with increasing pressure, while the amplitude of the ferroelectric polarization was steeply suppressed at around 8 GPa. A possible origin of the observed pressure effects on the ferroelectric property in the multiferroic TLA is discussed in terms of a ferroelectric-antiferroelectric transition and structural domain rearrangement by uniaxial stress. [ABSTRACT FROM AUTHOR]

Abstract: The electrical conductivities of natural pyrolitic mantle and MORB materials were measured at high pressure and temperature covering the entire lower mantle conditions up to 133GPa and 2650K. In contrast to the previous laboratory-based models, our data demonstrate that the conductivity of pyrolite does not increase monotonically but varies dramatically with depth in the lower mantle; it drops due to high-spin to low-spin transition of iron in both perovskite and ferropericlase in the mid-lower mantle and increases sharply across the perovskite to post-perovskite phase transition at the D″ layer. We also found that the MORB exhibits much higher conductivity than pyrolite. The depth–conductivity profile measured for pyrolite does not match the geomagnetic field data below about 1500-km depth, possibly suggesting the existence of large quantities of subducted MORB crust in the deep lower mantle. The observations of geomagnetic jerks suggest that the electrical conductivity may be laterally heterogeneous in the lowermost mantle with high anomaly underneath Africa and the Pacific, the same regions as large low shear-wave velocity provinces. Such conductivity and shear-wave speed anomalies are also possibly caused by the deep subduction and accumulation of dense MORB crust above the core–mantle boundary. [Copyright &y& Elsevier]

• Eu2+ and Eu3+ mixed-valence state phases were observed in EuH x for the first time. • Structural and valence phase diagram of EuH 2 and EuH x (2< x ≤ 3) compressed in H 2 is revealed. • Mössbauer spectroscopy can be a marker to estimate how much hydrogen is stored in some metal hydrides. • Ni 2 In-type structure of EuH 2 under compression allows the reaction with H 2. ga1 Raman scattering, Mössbauer spectroscopy, and X-ray diffraction measurements have revealed that EuH x compressed in high-pressure H 2 exhibits the crystal structure changes and the divalent (Eu2+) to trivalent (Eu3+) changes via two Eu2+/Eu3+ mixed-valence phases: EuH x -I (Pnma , x = 2, Eu2+) → EuH x -II (P 6 3 / mmc , x = 2, 7.0 GPa, Eu2+) → EuH x -III (I 4/ m , x ≃ 2.2, 7.0–9.0 GPa, Eu2+/Eu3+) → EuH x -V (x ≃ 2.8, 9.0–12.4 GPa, Eu2+/Eu3+) → EuH x -VI (x ≃ 3, 12.4–14.4 GPa, Eu3+) → EuH x -VII (x ≃ 3, 14.4–16 GPa, Eu3+) → EuH x -IV (I 4/ mmm , x ≃ 3, 16 GPa – , Eu3+). The EuH x -II transforms to EuH x -III at a constant pressure near 7.0 GPa due to the reaction with H 2. Our results also demonstrate that Mössbauer spectroscopy can be a useful marker to detect the hydrogen storing in metal hydrides. [ABSTRACT FROM AUTHOR]

Recent discovery of a phase transition from perovskite to post-perovskite suggests that the physical properties of Earth's Lowermost mantle, called the D′ Layer, may be different from those of the overlying mantle. We report that the electrical conductivity of (Mg0.9Fe0.1)SiO3 post-perovskite is >10² siemens per meter and does not vary greatly with temperature at the conditions of the D′ layer. A post-perovskite layer above the core-mantle boundary would, by electromagnetic coupling, enhance the exchange of angular momentum between the fluid core and the solid mantle, which can explain the observed changes in the length of a day on decadal time scales. Heterogeneity in the conductivity of the Lowermost mantle is likely to depend on changes in chemistry of the boundary region, not fluctuations in temperature. [ABSTRACT FROM AUTHOR]

Abstract: Thiospinel CuCrZrS4 exhibits ferromagnetic properties below its Curie temperature at . X-ray diffraction studies and the electrical resistance measurements were carried out on the thiospinel under high pressure up to 50 and 58GPa, respectively, at room temperature using a diamond-anvil cell. X-ray powder diffraction studies elucidated that a new high-pressure phase existed above 15Gpa. An anomaly in the electrical resistance was observed at around 15GPa, which is associated with structure transition to a high-pressure phase discovered by X-ray diffraction. Temperature dependence of the electrical resistance measurements revealed that CuCrZrS4 transforms from semi conductive to metallic compound under high pressure. [Copyright &y& Elsevier]

Abstract: We performed synchrotron X-ray powder diffraction experiments on the filled skutterudite at high pressure and low temperature to investigate the role of structural changes in the metallization and superconducting transition above 11GPa. We compared the structural parameters between the insulating and metallic phases. An anomalous enhancement of the P atomic displacement is observed at 17.0GPa and 10K away from the cubic sublattice are observed. This change may play a key role to the metallization at higher pressure. [Copyright &y& Elsevier]

Abstract: We have carried out electrical resistivity experiments on the non-centrosymmetric compound CeIrGe3 under high pressures up to 24GPa. CeIrGe3 is an antiferromagnet with the Néel temperature and a successive magnetic transition at at ambient pressure. With increasing pressure, and merge around 3GPa, becomes unchanged up to 10GPa, and indicates a step-like decrease up to 20GPa. Further increasing pressure, we have found superconductivity above 20GPa with a transition temperature of 1.6K at 24GPa. The upper critical field for the magnetic field along the tetragonal [001] direction is expected to be much larger than 15T. [ABSTRACT FROM AUTHOR]

In colloidal quantum dots (QDs), excitons are confined within nanoscale dimensions, and the relaxation of hot electrons occurs through Auger cooling. The behavior of hot electrons is evident under ambient pressure. Nanocrystal characteristics, including their size, are key to determining hot electron behavior because they serve as the stage. Applying pressure to materials can effectively modify this stage by providing a means to reversibly control interatomic distances. Unlike the behavior under ambient conditions, the pressure-dependent behavior remains unclear. In this study, InP/ZnS QDs were synthesized, and their pressure-dependent ultrafast carrier dynamics were analyzed using fs-transient absorption spectroscopy. The hot electron relaxation remained nearly constant up to the threshold pressure, suggesting constant interaction between electrons and holes. However, above this threshold, the hot electron relaxation was accelerated by trapping from higher excited states. This study contributes to establishing a fundamental understanding of the pressure-dependent behavior of hot electrons in QDs.

The search for high-temperature superconducting superhydrides has recently moved into a new phase by going beyond extensively probed binary compounds and focusing on ternary ones with vastly expanded material types and configurations for property optimization. Theoretical and experimental works have revealed promising ternary compounds that superconduct at or above room temperature, but it remains a pressing challenge to synthesize stoichiometric ternary compounds with a well-resolved crystal structure that can host high-temperature superconductivity at submegabar pressures. Here, we report on the successful synthesis of ternary LaBeH&#95;{8} obtained via compression in a diamond anvil cell under 110-130 GPa. X-ray diffraction unveils a rocksalt-like structure composing La and BeH&#95;{8} units in the lattice. Transport measurements determined superconductivity with critical temperature T&#95;{c} up to 110 K at 80 GPa, as evidenced by a sharp drop of resistivity to zero and a characteristic shift of T&#95;{c} driven by a magnetic field. Our experiment establishes the first superconductive ternary compound with a resolved crystal structure. These findings raise the prospects of rational development of the class of high-T&#95;{c} superhydrides among ternary compounds, opening greatly expanded and more diverse structural space for exploration and discovery of superhydrides with enhanced high-T&#95;{c} superconductivity.

A sharp focus of current research on superconducting superhydrides is to raise their critical temperature T c at moderate pressures. Here, we report a discovery of giant enhancement of T c in CeH 9 obtained via random substitution of half Ce by La, leading to equal-atomic (La,Ce)H 9 alloy stabilized by maximum configurational entropy, containing the LaH 9 unit that is unstable in pure compound form. The synthesized (La,Ce)H 9 alloy exhibits T c of 148-178 K in the pressure range of 97-172 GPa, representing up to 80% enhancement of T c compared to pure CeH 9 and showcasing the highest T c at sub-megabar pressure among the known superhydrides. This work demonstrates substitutional alloying as a highly effective enabling tool for substantially enhancing T c via atypical compositional modulation inside suitably selected host crystal. This optimal substitutional alloying approach opens a promising avenue for synthesis of high-entropy multinary superhydrides that may exhibit further increased T c at even lower pressures., (© 2022. The Author(s).)

Polyhydrides are a novel class of superconducting materials with extremely high critical parameters, which is very promising for sensor applications. On the other hand, a complete experimental study of the best so far known superconductor, lanthanum superhydride LaH 10 , encounters a serious complication because of the large upper critical magnetic field H C2 (0), exceeding 120-160 T. It is found that partial replacement of La atoms by magnetic Nd atoms results in significant suppression of superconductivity in LaH 10 : each at% of Nd causes a decrease in T C by 10-11 K, helping to control the critical parameters of this compound. Strong pulsed magnetic fields up to 68 T are used to study the Hall effect, magnetoresistance, and the magnetic phase diagram of ternary metal polyhydrides for the first time. Surprisingly, (La,Nd)H 10 demonstrates completely linear H C2 (T) ∝ |T - T C |, which calls into question the applicability of the Werthamer-Helfand-Hohenberg model for polyhydrides. The suppression of superconductivity in LaH 10 by magnetic Nd atoms and the robustness of T C with respect to nonmagnetic impurities (e.g., Y, Al, C) under Anderson's theorem gives new experimental evidence of the isotropic (s-wave) character of conventional electron-phonon pairing in lanthanum decahydride., (© 2022 Wiley-VCH GmbH.)

The discovery of superconductivity at 260 K in hydrogen-rich compounds like LaH 10 re-invigorated the quest for room temperature superconductivity. Here, we report the temperature dependence of the upper critical fields μ 0 H c2 (T) of superconducting H 3 S under a record-high combination of applied pressures up to 160 GPa and fields up to 65 T. We find that H c2 (T) displays a linear dependence on temperature over an extended range as found in multigap or in strongly-coupled superconductors, thus deviating from conventional Werthamer, Helfand, and Hohenberg (WHH) formalism. The best fit of H c2 (T) to the WHH formalism yields negligible values for the Maki parameter α and the spin-orbit scattering constant λ SO . However, H c2 (T) is well-described by a model based on strong coupling superconductivity with a coupling constant λ ~ 2. We conclude that H 3 S behaves as a strong-coupled orbital-limited superconductor over the entire range of temperatures and fields used for our measurements.

We have produced a superconducting binary-elements intercalated graphite, Ca x Sr 1-x C y , with the intercalation of Sr and Ca in highly-oriented pyrolytic graphite; the superconducting transition temperature, T c , was ~3 K. The superconducting Ca x Sr 1-x C y sample was fabricated with the nominal x value of 0.8, i.e., Ca 0.8 Sr 0.2 C y . Energy dispersive X-ray (EDX) spectroscopy provided the stoichiometry of Ca 0.5(2) Sr 0.5(2) C y for this sample, and the X-ray powder diffraction (XRD) pattern showed that Ca 0.5(2) Sr 0.5(2) C y took the SrC 6 -type hexagonal-structure rather than CaC 6 -type rhombohedral-structure. Consequently, the chemical formula of Ca x Sr 1-x C y sample could be expressed as 'Ca 0.5(2) Sr 0.5(2) C 6 '. The XRD pattern of Ca 0.5(2) Sr 0.5(2) C 6 was measured at 0-31 GPa, showing that the lattice shrank monotonically with increasing pressure up to 8.6 GPa, with the structural phase transition occurring above 8.6 GPa. The pressure dependence of T c was determined from the DC magnetic susceptibility and resistance up to 15 GPa, which exhibited a positive pressure dependence of T c up to 8.3 GPa, as in YbC 6 , SrC 6 , KC 8 , CaC 6 and Ca 0.6 K 0.4 C 8 . The further application of pressure caused the rapid decrease of T c . In this study, the fabrication and superconducting properties of new binary-elements intercalated graphite, Ca x Sr 1-x C y , are fully investigated, and suitable combinations of elements are suggested for binary-elements intercalated graphite.

A superconducting critical temperature above 200 K has recently been discovered in H 2 S (or D 2 S) under high hydrostatic pressure1, 2. These measurements were interpreted in terms of a decomposition of these materials into elemental sulfur and a hydrogen-rich hydride that is responsible for the superconductivity, although direct experimental evidence for this mechanism has so far been lacking. Here we report the crystal structure of the superconducting phase of hydrogen sulfide (and deuterium sulfide) in the normal and superconducting states obtained by means of synchrotron X-ray diffraction measurements, combined with electrical resistance measurements at both room and low temperatures. We find that the superconducting phase is mostly in good agreement with theoretically predicted body-centered cubic (bcc) structure for H 3 S (Ref.3). The presence of elemental sulfur is also manifest in the X-ray diffraction patterns, thus proving the decomposition mechanism of H 2 S to H 3 S + S under pressure4-6., Competing Interests: Competing financial interests The authors declare that they have no competing financial interests.

Earth continuously generates a dipole magnetic field in its convecting liquid outer core by a self-sustained dynamo action. Metallic iron is a dominant component of the outer core, so its electrical and thermal conductivity controls the dynamics and thermal evolution of Earth's core. However, in spite of extensive research, the transport properties of iron under core conditions are still controversial. Since free electrons are a primary carrier of both electric current and heat, the electron scattering mechanism in iron under high pressure and temperature holds the key to understanding the transport properties of planetary cores. Here we measure the electrical resistivity (the reciprocal of electrical conductivity) of iron at the high temperatures (up to 4,500 kelvin) and pressures (megabars) of Earth's core in a laser-heated diamond-anvil cell. The value measured for the resistivity of iron is even lower than the value extrapolated from high-pressure, low-temperature data using the Bloch-Grüneisen law, which considers only the electron-phonon scattering. This shows that the iron resistivity is strongly suppressed by the resistivity saturation effect at high temperatures. The low electrical resistivity of iron indicates the high thermal conductivity of Earth's core, suggesting rapid core cooling and a young inner core less than 0.7 billion years old. Therefore, an abrupt increase in palaeomagnetic field intensity around 1.3 billion years ago may not be related to the birth of the inner core.

Zoysiais a warm-season turfgrass, which comprises 11 allotetraploid species (2n= 4x= 40), each possessing different morphological and physiological traits. To characterize the genetic systems of Zoysia plants and to analyse their structural and functional differences in individual species and accessions, we sequenced the genomes of Zoysia species using HiSeq and MiSeq platforms. As a reference sequence of Zoysia species, we generated a high-quality draft sequence of the genome of Z. japonica accession 'Nagirizaki' (334 Mb) in which 59,271 protein-coding genes were predicted. In parallel, draft genome sequences of Z. matrella 'Wakaba' and Z. pacifica 'Zanpa' were also generated for comparative analyses. To investigate the genetic diversity among the Zoysia species, genome sequence reads of three additional accessions, Z. japonica'Kyoto', Z. japonica'Miyagi' and Z. matrella'Chiba Fair Green', were accumulated, and aligned against the reference genome of 'Nagirizaki' along with those from 'Wakaba' and 'Zanpa'. As a result, we detected 7,424,163 single-nucleotide polymorphisms and 852,488 short indels among these species. The information obtained in this study will be valuable for basic studies on zoysiagrass evolution and genetics as well as for the breeding of zoysiagrasses, and is made available in the 'Zoysia Genome Database' at http://zoysia.kazusa.or.jp., (© The Author 2016. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.)

S-band metals such as alkali and alkaline earth metals do not undergo a superconducting transition (SCT) at ambient pressure, but their high-pressure phases do. By contrast, room-temperature stable electride [Ca(24)Al(28)O(64)](4+)⋅4e(-) (C12A7:e(-)) in which anionic electrons in the crystallographic sub-nanometer-size cages have high s-character exhibits SCT at 0.2-0.4 K at ambient pressure. In this paper, we report that crystal and electronic structures of C12A7:e(-) are close to those of the high-pressure superconducting phase of alkali and alkaline earth metals and the SCT of both materials is induced when electron nature at Fermi energy (EF) switches from s- to sd-hybridized state., (© 2015 The Author(s) Published by the Royal Society. All rights reserved.)