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Compressed hydrogen-rich compounds have received extensive attention as appealing contenders for superconductors, and further challenges are maintaining the stability and superconductivity of hydrides at lower pressures. In this work, we found several novel hydrides YZrH6, YZrH8 and YZrH12 with excellent superconductivity in the Y-Zr-H ternary system. Interestingly, YZrH6 with an A15-type structure can maintain dynamic stability down to 0.01 GPa and still with a critical temperature (Tc) of 16 K. YZrH8 and YZrH12 have high Tc of 70 K and 183 K at 200 GPa and 160 GPa, respectively. The phonon modes associated with H atoms contribute significantly to the electron-phonon coupling, and the H-driven electronic density of states play an important role in superconductivity. These findings highlight relationship between the H-driven electronic density of states, electron-phonon coupling and the superconductivity in a distinct class of hydrides, opening new avenues for designing and optimizing new hydrogen-rich high temperature superconductors., 15 pages, 8 figures

Metal hydrides, generally formed by high pressure combined with high-temperature conditions, have attracted substantial interest due to their promising high-energy density and high-temperature supe...

Optical anti-counterfeiting and encryption have become a hotspot in information security. However, the advanced optical anti-counterfeiting technology still suffers from low security by single-luminescent mode. Herein, we present a novel multi-mode anti-counterfeiting strategy based on K3LuSi2O7: Tb3+/Bi3+ (KLSO: Tb3+/Bi3+) phosphors for the first time. KLSO not only provides various lattice sites for Bi3+ ions occupying to achieve tunable luminescence but can also be non-equivalently substituted by Tb3+ ions to produce persistent or thermo-luminescence. Furthermore, in the pattern "8888" constructed by the mixture of polyacrylic acid (PAA) with KLSO: Tb3+/Bi3+ phosphors, we selectively trigger the three luminescent modes of Bi3+ and Tb3+ ions to realize the design of differential display in the fields of thermal response, time resolution, and luminescence color for optical anti-counterfeiting. The differentiated display can only be presented under specific multi-stimuli response, which further improves the security of information. Our work provides a new insight for designing advanced materials and can be expected to inspire future studies to explore optical anti-counterfeiting technology.

The influence of doping on the high-Tc superconductor Im-3 m-H3S has attracted great attention since the addition of the external elements is expected to further increase the Tc value or lower the stable pressure of H3S. Here, we systematically investigated the electronic structures and superconductive properties of H6SX (X = N, P, As, O, Se, F, Cl, and Br) through first-principle calculations at 200 GPa. Only H6SP, H6SSe, and H6SBr are dynamically stable and the Tc of H6SSe can reach 182 K. The bonding analysis shows that stronger covalent interactions are beneficial for higher Tc values for these ternary metallic covalent superconductors. The improvement of Tc in doped H3S systems could be obtained through introducing stronger covalent interactions and light atomic massive. In addition, we found that the replacement of Br atoms can reduce the stable pressure of H3S to 150 GPa with Tc about 159–174 K.

Hydrogen-rich compounds have long been considered as one of the hotspot materials for achieving room-temperature superconductivity. We systematically investigate the high-pressure phase diagram of the K-H system and identified two unreported clathrate extreme superhydrides KH

Palladium hydrides (PdH

The connection between magnetism and superconductivity has long been discussed since the discovery of Fe-based superconductors. Here, we report the discovery of a pressure-induced transition from a spin to a superconducting state in novel MnN2 based on ab initio calculations. The superconducting state can be obtained in two ways: the first is the pressure-induced transition from an AFM-P21/m to an NM-I4/mmm phase at 30 GPa, while the other is the pressure-induced transition from an FM-I4/mmm phase to magnetic vanishing at 14 GPa, which leads to a structural transition with the distortion of octahedrons to tetragonal pyramids. NM-I4/mmm-MnN2 is superconductive with Tc ≈ 17.6 K at 0 GPa. In the second way, electronic structure calculations indicate that the system transforms from a high-spin state to a low-spin state due to increasing crystal-field splitting, causing disappearance of magnetism; more electron occupancy around the Fermi level drives the emergence of superconductivity. Remarkably, I4/mmm-MnN2 can achieve mutual spin-to-superconducting state transformation by pressure. Moreover, the AFM-P21/m-MnN2 phase is extremely incompressible with the hardness above 20 GPa. Our results provide a reasonable and systematic interpretation for the connection between magnetism and superconductivity and give clues for achieving spin-to-superconducting switching materials with certain crystal features.

Superionic states simultaneously exhibit properties of a fluid and a solid. Proton (H+) superionicity in ice, H3O, He-H2O, and He-NH3 compounds is well-studied. However, hydride (H-) superionicity in H-rich compounds is rare, being associated with instability and strongly reducing conditions. Silicon, sodium, and hydrogen are abundant elements in many astrophysical bodies. Here, we use first-principles calculations to show that, at high pressure, Na, Si, and H can form several hypervalent compounds. A previously unreported superionic state of Na2SiH6 results from unconstrained H- in the hypervalent [SiH6]2- unit. Na2SiH6 is dynamically stable at low pressure (3 GPa), becoming superionic at 5 GPa, and re-entering solid/fluid states at about 25 GPa. Our observation of H- transport opens up a new field of H- conductors. It also has implications for the formation of conducting layers at depth in exotic carbon exoplanets, potentially enhancing the habitability of such planets.

The ZnO-TiO

A new phase P3̄m1 of K2SiH6 was uncovered at ambient pressure by means of first-principles structure searches, which is a promising hydrogen storage material with high gravimetric and volumetric hydrogen densities.

The discovery of H3S and LaH10 is an important step towards the development of room temperature superconductors which fuels the enthusiasm for finding promising superconductors among hydrides at high pressure. In the present study, three new and stable stoichiometric MoH5, MoH6 and MoH11 compounds were found in the pressure range of 100–300 GPa. The highly hydrogen-rich phase of Cmmm-MoH11 has a layered structure that contains various forms of hydrogen: H, H2− and H3− units. It is a high-Tc material with an estimated Tc value in the range of 165–182 K at 250 GPa. The same structures are also found in NbH11, TaH11, and WH11, each material showing Tc ranging from 117 to 168 K. By combining the method of using two coupling constants λopt and λac, and two characteristic frequencies (optical and acoustic) with first-principle calculations, we found that the high values of Tc are mainly caused by the presence of high frequency optical modes, but the acoustic modes also play a noticeable role.

In this work, eight types of poly (ether-ether-ketone) (PEEK)/Ni foam co-continuous phase composites (PEEK–Nis) were fabricated by hot pressing. Unfilled PEEK polymer was also prepared in two different methods: P-1 was prepared by the same method with PEEK–Nis, and P-2 was synthesised via extrusion. The tensile properties and fracture processes of PEEK–Nis were investigated and compared with those of unfilled PEEK polymer. Results showed that the stress–strain curves of PEEK–Nis exhibited elastic deformation, yielding and necking. Nickel foam could improve the tensile toughness and elongation-at-break of PEEK–Nis by increasing the number of edges or decreasing the pore quantities of Ni foam. The Young's moduli of PEEK–Nis were related only to metal content. The Young's moduli of PEEK–Nis increased with Ni volume content, and this relationship showed a secondary upward trend. The fracture surfaces of 10 kinds of materials after tensile tests were observed through scanning electron microscopy. Mirror, mist and hackle zones were found on the fracture surfaces of PEEK–Nis and the unfilled PEEK polymer. Morphological analysis showed that a crack could begin in one site and propagate within the material. However, the Ni prism structure could effectively decelerate crack propagation and even stop the crack, causing the crack to restart in the mirror zone. Two main parameters influence the tensile behaviours of PEEK–Nis including the quantity of Ni edge (or PPI value) and edge thickness. The Ni edge quantity of the foam played a positive role in the tensile behaviour of PEEK–Nis. However the effect of edge thickness has two side effects. In Ni foam, intergranular fracture replaced plastic fracture and degraded tensile performance if edge thickness exceeded 70 μm. Amongst all PEEK–Nis studied in this work, PEEK–NiA-1 exhibits the best performance and its tensile toughness was more than 1.6 times that of P-1.

Following the discovery of high-temperature superconductivity in the La–H system, we studied the formation of new chemical compounds in the barium-hydrogen system at pressures from 75 to 173 GPa. Using in situ generation of hydrogen from NH3BH3, we synthesized previously unknown superhydride BaH12 with a pseudocubic (fcc) Ba sublattice in four independent experiments. Density functional theory calculations indicate close agreement between the theoretical and experimental equations of state. In addition, we identified previously known P6/mmm-BaH2 and possibly BaH10 and BaH6 as impurities in the samples. Ab initio calculations show that newly discovered semimetallic BaH12 contains H2 and H3– molecular units and detached H12 chains which are formed as a result of a Peierls-type distortion of the cubic cage structure. Barium dodecahydride is a unique molecular hydride with metallic conductivity that demonstrates the superconducting transition around 20 K at 140 GPa.

The discovery of the high-temperature superconducting state in the compounds of hydrogen, carbon and sulfur with a critical temperature (Tc) of 288 K at high pressure is an important milestone towards room-temperature superconductors. Here, we have extensively investigated the high-pressure phases of CS2H10, and found four phases Cmc21, P3m1, Pm1 and Pm. Among them, P3m1 can be dynamically stable at a pressure as low as 50 GPa, and Cmc21 has a high Tc of 155 K at 150 GPa. Both Cmc21 and P3m1 are host–guest hydrides, in which CH4 molecules are inserted into Imm-H3S and R3m-H3S sublattices, respectively. Their Tc is dominated by the H3S lattice inside. The insertion of CH4 molecules greatly reduces the pressure required for the stability of the original H3S lattice, but it has a negative impact on superconductivity which cannot be ignored. By studying the effect of CH4 insertion in the H3S lattice, we can design hydrides with a Tc close to that of H3S and a greatly reduced pressure required for stability.

Our paper is concerned with the specific hydrogen compound MoH

Stabilization of the pentazole anion only by acidic circumstances entrapment impedes the realization of a full-nitrogen substance; however, compression of nitrogen-rich nitrides has been recommend as an alternative way that has more controllable advantages to acquire the atomic nitrogen states. Through the structure searches are in conjunction with first-principle calculations, moderate pressure stabilized nitrogen-rich zinc nitrides with abundant extended nitrogen structures, e.g., cyclo-N5, infinite -(N4)n- chains, three-point stars N(N3), and N2 dumbbells, are predicted. The resonance between alternating σ bonds and π bonds in poly nitrogen sublattices takes charge of the coexistence of single and double bonds. The Zn(N5)2 salt has a noteworthy energy density (6.57 kJ/g) among the reported binary metal nitrides and synthesized pentazolate hydrates. An excellent Vicker's hardness (34 GPa) and detonation performance is unraveled. Although Zn(N5)2 salt is not expected to be recoverable at ambient conditions, it is worth noting that Zn(N5)2 is found to be stable at a very low pressure of ∼30 GPa, which is only half of those pressures required to synthesize CsN5. We clarified that the metal-centering octahedral pentazolate framework was entrapped by dual ionic-covalent bonds. More importantly, the covalent bonding can effectively enhance the chemical insensitivity and thermal stability, further preventing the autodecomposition of monatomic solid N5- anions into dinitrogen. Meanwhile, a unique topological pseudogap that attached to a metastable phase of ZnN4 salt is exposed for the first time, due to the dual effects of strong covalent sp2 hybridization interaction and the origin of ionic states.

Highly compressed hydrides have been at the forefront of the search for high-Tc superconductivity. The recent discovery of record-high Tc’s in H3S and LaH10±x under high pressure fuels the enthusia...

Strain engineering is a more effective and green method to achieve the nonmetal-to-metal transition than metal doping. The elastic strain field can effectively change the atomic orbital interaction, achieving the metallization of materials. Taking IrAs3 as a prototype, the strain–stress behaviors of binary skutterudite are investigated. A reversible semiconductor-to-metal (SM) transition can be easily achieved by only an ∼9% strain. The strain-induced Jahn–Teller effect of IrAs6 octahedra and the breakage of As4-rings dominate the metallization. Unexpectedly, the metal element Ir in IrAs3 becomes an electron acceptor due to its higher electronegativity and the effect of the octahedral field.

Lanthanum (La), the first member of the lanthanide elements, recently aroused interests due to the discovery of high-T c superconductor LaH10 under high pressures and its unique superconducting properties. Here, we study the phase transitions, superconductivity and mechanical properties of metallic La under high pressures by first-principle calculations. The known face-centered cubic (fcc) phase with space group F m 3 ¯ m still exists above 100 GPa. And it transforms into an unprecedented body-centered tetragonal (bct) phase with space group I4/mmm above 180 GPa, which expands the high pressure phase transition sequence. Further calculations show that the superconducting transition temperature T c of fcc phase decreases with increasing pressure with the rate of −0.13 K GPa−1, in good agreement with the experimental results. For the bct phase, the estimated superconducting transition temperature is very low with T c of 0.7 K at 200 GPa. The calculations of mechanical properties show that both of fcc and bct phases are compressible and brittle.

Room-temperature superconductivity has been a long-held dream and an area of intensive research. The discovery of H3S and LaH10 under high pressure, with superconducting critical temperatures (T c) above 200 K, sparked a race to find room temperature superconductors in compressed superhydrides. In recent groundbreaking work, room-temperature superconductivity of 288 K was achieved in carbonaceous sulfur hydride at 267 GPa. Here, we describe the important attempts of hydrides in the process of achieving room temperature superconductivity in decades, summarize the main characteristics of high-temperature hydrogen-based superconductors, such as hydrogen structural motifs, bonding features, electronic structure as well as electron–phonon coupling etc. This work aims to provide an up-to-date summary of several type hydrogen-based superconductors based on the hydrogen structural motifs, including covalent superhydrides, clathrate superhydrides, layered superhydrides, and hydrides containing isolated H atom, H2 and H3 molecular units.

The combination of electride state and superconductivity within the same compound, e.g., ${[{\mathrm{Ca}}_{24}{\mathrm{Al}}_{28}{\mathrm{O}}_{6}]}^{4+}(4{e}^{\ensuremath{-}})$, opens up a new category of conventional superconductors. However, neither the underlying causations to explain superconducting behaviors nor effects of interstitial quasiatoms (ISQs) on superconductivity remain unclear. Here we have designed an efficient and resource-saving method to identify superconducting electrides only by chemical compositions and bonding characteristics. A representative superconducting electride ${\mathrm{Li}}_{6}\mathrm{C}$ with a noteworthy ${T}_{c}$ of 10 K below 1 Mbar among the known binary electrides has been revealed. Our first-principles studies unveil that the anomalous $sp$-hybridized cage-state ISQs, as a guest in ${\mathrm{Li}}_{6}\mathrm{C}$, exhibit unexpected ionic and covalent bonds, which act as a chemical precompression to lower dynamically stable pressure. More importantly, we uncover that, contrary to common expectations, the high ${T}_{c}$ is attributed to the strong electron-phonon coupling derived from the synergy of interatomic coupling effect, phonon softening caused by Fermi surface nesting, and phonon-coupled bands, which are mainly dominated by host $sp$-hybridized electrons, rather than the ISQs. Our present results elucidate a new superconducting mechanism of electrides and shed light on the way for seeking a high-${T}_{c}$ superconductor at lower pressures in cage-state electrides.

The discovery of the high-temperature superconducting state in the compounds of hydrogen, carbon and sulfur with a critical temperature (

Invigorated by the high-temperature superconductivity in ternary hydrogen-dominated compounds under high pressures, we systematically explored high-pressure phase diagrams, electronic properties, lattice dynamics, and superconductivity of ternary Na-Al-H systems using ab initio methods. We found three stable compounds of ${\mathrm{NaAlH}}_{4}$, ${\mathrm{NaAlH}}_{6}$, and ${\mathrm{NaAlH}}_{8}$, as well as a metastable compound of ${\mathrm{NaAlH}}_{7}$ under high pressures. Except for ${\mathrm{NaAlH}}_{4}$, they all containing ${\mathrm{H}}^{\ensuremath{-}}$ and ${\mathrm{H}}_{2}$ units. Electronic structure calculations reveal that ${\mathrm{NaAlH}}_{7}$ and ${\mathrm{NaAlH}}_{8}$ are metallic, while ${\mathrm{NaAlH}}_{4}$ and ${\mathrm{NaAlH}}_{6}$ are semiconductors. In addition, ${\mathrm{NaAlH}}_{8}$ exhibits a phonon anomaly (dip) in multiple phonon branches along the A-M direction. The phonon anomaly induced by Fermi-surface nesting boosts the electron-phonon coupling strength, and as a result, a superconducting transition temperature ${T}_{c}$ of 55 K was produced at 300 GPa.

The discoveries of high-temperature superconductivity in ${\mathrm{H}}_{3}\mathrm{S}$ and ${\mathrm{LaH}}_{10}$ have excited the search for superconductivity in compressed hydrides, finally leading to the first discovery of a room-temperature superconductor in a carbonaceous sulfur hydride. In contrast to rapidly expanding theoretical studies, high-pressure experiments on hydride superconductors are expensive and technically challenging. Here, we experimentally discovered superconductivity in two new phases, $Fm\overline{3}m\text{\ensuremath{-}}{\mathrm{CeH}}_{10}$ (SC-I phase) and $P{6}_{3}/mmc\text{\ensuremath{-}}{\mathrm{CeH}}_{9}$ (SC-II phase) at pressures that are much lower ($l100\text{ }\text{ }\mathrm{GPa}$) than those needed to stabilize other polyhydride superconductors. Superconductivity was evidenced by a sharp drop of the electrical resistance to zero and decreased critical temperature in deuterated samples and in external magnetic field. SC-I has ${T}_{c}=115\text{ }\text{ }\mathrm{K}$ at 95 GPa, showing an expected decrease in further compression due to the decrease of the electron-phonon coupling (EPC) coefficient $\ensuremath{\lambda}$ (from 2.0 at 100 GPa to 0.8 at 200 GPa). SC-II has ${T}_{c}=57\text{ }\text{ }\mathrm{K}$ at 88 GPa, rapidly increasing to a maximum ${T}_{c}\ensuremath{\sim}100\text{ }\text{ }\mathrm{K}$ at 130 GPa, and then decreasing in further compression. According to the theoretical calculation, this is due to a maximum of $\ensuremath{\lambda}$ at the phase transition from $P{6}_{3}/mmc\text{\ensuremath{-}}{\mathrm{CeH}}_{9}$ into a symmetry-broken modification $C2/c\text{\ensuremath{-}}{\mathrm{CeH}}_{9}$. The pressure-temperature conditions of synthesis affect the actual hydrogen content and the actual value of ${T}_{c}$. Anomalously low pressures of stability of cerium superhydrides make them appealing for studies of superhydrides and for designing new superhydrides with stability at even lower pressures.

Hydrogen-rich compounds are being extensively explored theoretically and experimentally as potential hydrogen storage materials. In this work, we predicted a hydrogen-rich compound rhodium trihydride ($\mathrm{Rh}{\mathrm{H}}_{3}$) with a high volumetric hydrogen density of 212.5 g/L by means of ab initio calculations. The $\mathrm{Rh}{\mathrm{H}}_{3}$ with Pnma symmetry is thermodynamically stable and accessible through synthesis above 40 GPa. The compound is dynamically and mechanically stable at ambient pressure. Further calculation suggests a probable dehydrogenation temperature ${T}_{\mathrm{des}}$ of $65{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$ at ambient pressure with decomposition route to $\mathrm{Rh}+{\mathrm{H}}_{2}$. High volumetric hydrogen density and moderate dehydrogenation temperature place $\mathrm{Rh}{\mathrm{H}}_{3}$ as one of the best hydrogen storage materials. Our work encourages the experimental synthesis of $\mathrm{Rh}{\mathrm{H}}_{3}$ at high pressure.

Optical anti-counterfeiting and encryption have become a hotspot in information security. However, the advanced optical anti-counterfeiting technology still suffers from low security by single-luminescent mode. Herein, we present a novel multi-mode anti-counterfeiting strategy based on K

Superionic states simultaneously exhibit properties of a fluid and a solid. Proton (H

Hydrogen-based superconductors provide a route to the long-sought goal of room-temperature superconductivity, but the high pressures required to metallize these materials limit their immediate application. For example, carbonaceous sulfur hydride, the first room-temperature superconductor, can reach a critical temperature (Tc) of 288 K only at the extreme pressure of 267 GPa. The next recognized challenge is the realization of room-temperature superconductivity at significantly lower pressures. Here, we propose a strategy for the rational design of high-temperature superconductors at low pressures by alloying small-radius elements and hydrogen to form ternary hydride superconductors with alloy backbones. We identify a hitherto unknown fluorite-type backbone in compositions of the form AXH8, which exhibit high temperature superconductivity at moderate pressures. The Fm-3m phase of LaBeH8, with a fluorite-type H-Be alloy backbone, is predicted to be metastable and superconducting with a Tc ~ 191 K at 50 GPa; a substantially lower pressure than that required by the geometrically similar clathrate hydride LaH10 (170 GPa). Our approach paves the way for finding high-Tc ternary hydride superconductors at conditions close to ambient pressures., 11 pages, 4 figures

All elements that form diatomic molecules, such as ${\mathrm{H}}_{2}$, ${\mathrm{N}}_{2}$, ${\mathrm{O}}_{2}$, ${\mathrm{Cl}}_{2}$, ${\mathrm{Br}}_{2}$, and ${\mathrm{I}}_{2}$, are destined to become atomic solids under sufficiently high pressure. However, as revealed by many experimental and theoretical studies, these elements show very different propensity and transition paths due to the balance of reduced volume, lone pair electrons, and interatomic bonds. The study of F under pressure can illuminate this intricate behavior since F, owing to its unique position on the periodic table, can be compared with H, with N and O, and also with other halogens. Nevertheless, F remains the only element whose solid structure evolution under pressure has not been thoroughly studied. Using a large-scale crystal structure search method based on first principles calculations, we find that, before reaching an atomic phase, F solid transforms first into a structure consisting of ${\mathrm{F}}_{2}$ molecules and F polymer chains and then into a structure consisting of F polymer chains and F atoms, a distinctive evolution with pressure that has not been seen in any other elements. Both intermediate structures are found to be metallic and become superconducting, a result that adds F to the elemental superconductors.

In this study, we prepared eight types of polyetheretherketone/nickel (PEEK/Ni) foam co-continuous phase composites (named “PEEK-Nis”) in which virgin PEEK was infiltrated into homologous hollow Ni structures by using hot pressing. Their Charpy impact behavior was investigated in accordance with ISO: 179-1, and the effect of the structure of the foam Ni on the impact properties of the PEEK-Nis was also studied. Compared with unfilled PEEK, the Ni prisms can effectively disperse, transfer, and absorb the energy of the pendulum, further improve the impact toughness of the PEEK-Nis and eventually lead to different fracture modes. The impact toughness of PEEK-Nis was mainly affected by Ni volume fraction, coating thickness, and pores per inch (PPI) value, which are mutually restricted. When the Ni content was less than 8.5%, the impact toughness of PEEK-Nis increased with an increase in PPI value. When the Ni content was between 8.5 and 18%, the impact toughness of PEEK-Nis increased with the coating thickness. When the Ni content exceeded 18%, the impact toughness decreased dramatically possibly because of the mechanical mismatch of the two-phase materials in PEEK-Nis. For further optimization, PEEK-NiB-2 was fabricated and had the most reasonable structure of the reinforcing phase. Among all PEEK-Nis, PEEK-NiB-2 exhibited the best impact toughness, with a value over two times that of unfilled PEEK.

Compression of hydrogen-rich hydrides has been proposed as an alternative way to attain the atomic metallic hydrogen state or high-temperature superconductors. However, it remains a challenge to get access to these states by synthesizing novel polyhydrides with unusually high hydrogen-to-metal ratios. Here we synthesize a series of cerium (Ce) polyhydrides by a direct reaction of Ce and H2 at high pressures. We discover that cerium polyhydride CeH9, formed above 100 GPa, presents a three-dimensional hydrogen network composed of clathrate H29 cages. The electron localization function together with band structure calculations elucidate the weak electron localization between H-H atoms and confirm its metallic character. By means of Ce atom doping, metallic hydrogen structure can be realized via the existence of CeH9. Particularly, Ce atoms play a positive role to stabilize the sublattice of hydrogen cages similar to the recently discovered near-room-temperature lanthanum hydride superconductors., Obtainment of hydrogen-rich metal hydrides that are high-temperature superconductors has been demonstrated under very high pressure, but is still largely unexplored. Here the authors synthesize CeH9, with a structure related to solid metallic hydrogen, at relatively low pressure and without need for heating.

The ab initio evolutionary algorithm is used to search for all thermodynamically stable ZnOS alloys at extreme pressure. Our calculations enable the discovery of a new stable structure at high pressure, namely, P21/m Zn8O2S6, as well as several metastable structures. We find that pressure can be used as an effective approach to forming stable ZnOS alloys. The variation in band gap of P21/m Zn8O2S6 is calculated using a hybrid functional, which shows that P21/m Zn8O2S6 initially increases and then decreases. We also believe that P21/m Zn8O2S6 may be a potential material for increasing the efficiency of solar cells.

The search for high-temperature superconductivity is one of the research frontiers in physics. In the sulfur hydride system, an extremely high Tc (∼200 K) has been recently developed at pressure. However, the Meissner effect measurement above megabar pressures is still a great challenge. Here, we report the superconductivity identification of sulfur hydride at pressure, employing an in situ alternating-current magnetic susceptibility technique. We determine the superconducting phase diagram, finding that superconductivity suddenly appears at 117 GPa and Tc reaches 183 K at 149 GPa before decreasing monotonically with increasing pressure. By means of theoretical calculations, we elucidate the variation of Tc in the low-pressure region in terms of the changing stoichiometry of sulfur hydride and the further decrease in Tc owing to a drop in the electron–phonon interaction parameter λ. This work provides a new insight into clarifying superconducting phenomena and anchoring the superconducting phase diagram in the hydrides.