The recent discovery of large magnetoresistance in tungsten ditelluride provides a unique playground to find new phenomena and significant perspective for potential applications. The large magnetoresistance effect originates from a perfect balance of hole and electron carriers, which is sensitive to external pressure. Here we report the suppression of the large magnetoresistance and emergence of superconductivity in pressurized tungsten ditelluride via high-pressure synchrotron X-ray diffraction, electrical resistance, magnetoresistance and alternating current magnetic susceptibility measurements. Upon increasing pressure, the positive large magnetoresistance effect is gradually suppressed and turned off at a critical pressure of 10.5 GPa, where superconductivity accordingly emerges. No structural phase transition is observed under the pressure investigated. In situ high-pressure Hall coefficient measurements at low temperatures demonstrate that elevating pressure decreases the population of hole carriers but increases that of the electron ones. Significantly, at the critical pressure, a sign change of the Hall coefficient is observed.

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Coexisting arsenic (As) and fluoride (F) in groundwater poses severe health risks worldwide. Highly efficient simultaneous removal of As and F is therefore of great urgency and high priority. The purpose of this study was to fabricate a novel composite adsorbent and explore the mechanism for concurrent removal of As(V) and F at the molecular level. This bifunctional adsorbent with titanium and lanthanum oxides impregnated on granular activated carbon (TLAC) exhibits a pronounced As(V) and F adsorption capacity over commercially available iron-and aluminumbased adsorbents for synthetic and real contaminated groundwater samples. Synchrotron-based X-ray microfluorescence analysis demonstrates that La and Ti were homogeneously distributed on TLAC. Extended X-ray absorption fine structure spectroscopic results suggest that As(V) formed bidentate binuclear surface complex as evidenced by an averaged Ti−As bond distance of 3.34 Å in the presence of F. Adsorption tests and Fourier transform infrared spectroscopy analysis indicate that F was selectively adsorbed on lanthanum oxides. The surface configurations constrained with the spectroscopic results were formulated in the charge distribution multisite complexation model to describe the competitive adsorption behaviors of As(V) and F. The results of this study indicate that TLAC could be used as an effective adsorbent for simultaneous removal of As(V) and F.

SignificanceHigh-entropy alloys (HEAs) are made from multiple transition-metal elements in equimolar or near-equimolar ratios. The elements in HEAs arrange themselves randomly on the crystallographic positions of a simple lattice. In addition to their excellent mechanical properties, one HEA has been reported to display superconductivity. In this work, we report that the Ta–Nb–Hf–Zr–Ti high-entropy alloy superconductor exhibits extraordinarily robust zero-resistance superconductivity under pressure up to 190.6 GPa. This is an observation of the zero-resistance state of a superconductor all the way from 1-bar pressure to the pressure of the earth’s outer core without structure phase transition, making the superconducting HEA a promising candidate for new application under extreme condition.

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