51 research outputs found

    Pressure-Stabilized Semiconducting Electrides in Alkaline-Earth-Metal Subnitrides

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    High pressure is able to modify profoundly the chemical bonding and generate new phase structures of materials with chemical and physical properties not accessible at ambient conditions. We here report an unprecedented phenomenon on the pressure-induced formation of semiconducting electrides via compression of layered alkaline-earth subnitrides Ca<sub>2</sub>N, Sr<sub>2</sub>N, and Ba<sub>2</sub>N that are conducting electrides with loosely confined electrons in the interlayer voids at ambient pressure. Our extensive first-principles swarm structure searches identified the high-pressure semiconducting electride phases of a tetragonal <i>I</i>4̅2<i>d</i> structure for Ca<sub>2</sub>N and a monoclinic <i>Cc</i> structure shared by Sr<sub>2</sub>N and Ba<sub>2</sub>N, both of which contain atomic-size cavities with paring electrons distributed within. These electride structures are validated by the excellent agreement between the simulated X-ray diffraction patterns and the experimental data available. We attribute the emergence of the semiconducting electride phases to the p<i>–</i>d hybridization on alkaline-earth-metal atoms under compression as well as the filling of the p<i>–</i>d hybridized band due to the interaction between Ca and N. Our work provides a unique example of pressure-induced metal-to-semiconductor transition in compound materials and reveals unambiguously the electron-confinement topology change between different types of electrides

    Results of the incomplete factorial experiment evaluating dilute H<sub>2</sub>SO<sub>4</sub> pretreatment for <i>Triarrhena sacchariflora</i> (Maxim.) Nakai.

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    <p>K1 = Sum of index value of factor1, K2 =  Sum of index value of factor2, K1-bar = K1/2, K2-bar = K2/2.</p><p>Results of the incomplete factorial experiment evaluating dilute H<sub>2</sub>SO<sub>4</sub> pretreatment for <i>Triarrhena sacchariflora</i> (Maxim.) Nakai.</p

    Incomplete factorial experimental design of <i>Triarrhena sacchariflora</i> (Maxim.) Nakai with dilute sulfuric acid pretreatment.

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    <p>Incomplete factorial experimental design of <i>Triarrhena sacchariflora</i> (Maxim.) Nakai with dilute sulfuric acid pretreatment.</p

    Means and standards errors for lignocellulosic components and means for crystallinity for different digestion temperatures, N = 3<sup>1</sup>.

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    1<p>Means with larger standard errors in a column are based on a sample size of N = 2.</p>abcde<p>Means within a column with differing superscripts differ (P<0.05).</p><p>Means and standards errors for lignocellulosic components and means for crystallinity for different digestion temperatures, N = 3<sup><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114399#nt107" target="_blank">1</a></sup>.</p
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