Tungsten borides are among a distinct class of transition-metal light-element compounds with superior mechanical properties that rival those of traditional superhard materials. An in-depth understanding of these compounds, however, has been impeded by uncertainties regarding their complex crystal structures. Here, we examine a wide range of chemical compositions of tungsten borides using a recently developed global structural optimization approach. We establish thermodynamically stable structures and identify a large number of metastable phases. These results clarify and correct previous structural assignments and predict new structures for possible synthesis. Our findings provide crucial insights for understanding the rich and complex crystal structures of tungsten borides, which have broad implications for further exploration of this class of promising materials.

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A novel body-centered tetragonal CN(2) (4 units per cell), named as bct-CN(2), has been predicted here using our newly developed particle swarm optimization algorithm for crystal structure prediction. Bct-CN(2) is energetically much superior (3.022 eV per f.u.) to previously proposed pyrite structure and stable against decomposition into a mixture of diamond + N(2) or 1/3(C(3)N(4) + N(2)) above 45.4 GPa. No imaginary phonon frequencies in the whole Brillouin zone indicate bct-CN(2) is dynamically stable. The electronic calculations indicate that bct-CN(2) is a wide gap dielectric material with an indirect band gap of 3.6 eV. The ideal tensile, shear, and compressive strength at large strains of bct-CN(2) are examined to understand further the microscopic mechanism of the structural deformation. Strikingly, it is found that bct-CN(2) has high calculated ideal strength, bulk modulus, shear modulus, and simulated hardness, indicating its very incompressible and superhard nature. The results provide new thoughts for designing and synthesizing novel superhard carbon nitrides, and insights for understanding the mechanical properties.

In order to better utilize the superior transverse piezoelectric properties of [011] poled (1−x)Pb(Mg1∕3Nb2∕3)O3–xPbTiO3 single crystals with the composition near the morphotropic phase boundary, a complete set of elastic, dielectric, and piezoelectric constants of [011] poled 0.71Pb(Mg1∕3Nb2∕3)O3–0.29PbTiO3 single crystal was measured by ultrasonic and resonance methods at room temperature. The electromechanical coupling coefficient k32 and transverse piezoelectric constant d32 can reach 0.94 and −1883pC∕N, respectively. This complete set of material properties will provide convenience for device designs and fundamental theoretical studies.

A novel Co2P-3D PNC composite with Co2P NPs encapsulated in 3D porous N-doped carbon nanosheet networks was synthesized by a cobalt nitrate-induced PVP-blowing method combined with an in situ phosphidation process. The resultant Co2P-3D PNC anode delivers high specific capacity, enhanced rate capability, and improved cycling stability.

A series of anionic framework aluminophosphates, with different Al/P ratios, have been investigated by various solid-state NMR techniques, including 27Al, 31P magic angle spinning (MAS), 27Al-->31P cross polarization (CP), 27Al{31P} rotational echo double resonance (REDOR), and 31P{27Al} transfer of population double resonance (TRAPDOR). Different Al coordinations (AlO4b, AlO5b, and AlO6b) and P coordinations (PO4b, PO3bOt, PO2bO2t, and PObO3t), where b represents bridging oxygens and t represents terminal oxygens, can be unambiguously determined based on the solid-state NMR spectroscopy. Furthermore, a new method to determine the Al/P ratio of open-framework aluminophosphates has been established, which is useful for the understanding of unknown aluminophosphate structures.

A new spectrophotometric method using covalently attached capture antibody labeled with alkaline phosphatase is developed for the detection of fPSA.