Browsing by Author "Pathak, Manisha"

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    Li16Sr6Ge6N, Li16Sr6Ge6.5 and related lithium alkaline‐earth metal tetrelides : alternative filling of voids by nitride or tetrelide ions
    (2022) Höhn, Peter; Pathak, Manisha; Prots, Yurii; Ovchinnikov, Alexander; Schmidt, Marcus; Bobnar, Matej; Krnel, Mitja; Ormeci, Alim; Niewa, Rainer
    Large black single crystals with a metallic luster of Li16Sr6Ge6N and several other representatives of the series Li16Ae6Tt6N and Li16Ae6Tt6.5 (Ae=Ca, Sr; Tt=Si, Ge, Sn, Pb) were grown from mixtures of the respective elements with addition of binary alkaline‐earth metal nitrides or lithium nitride in the case of the nitrides. For the synthesis a modified high‐temperature centrifugation‐aided filtration (HTCAF) technique using reactive lithium melts was employed. These metallic phases crystallize in an ordered defect‐variant of the Sc11Ir4 type with selective occupation of the smaller octahedral voids in the origin (000) with N and the larger rhombic dodecahedral voids in (00 1/2) with Tt. Charge balance assuming the presence of exclusively closed shell ions for all examples accounts for an electronic excess. Diamagnetism despite metallic properties is consistent with results from electronic structure calculations.
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    The reduced nitridogermanates(III) Ca6[Ge2N6] and Sr6[Ge2N6] with Ge-Ge bonds
    (2021) Link, Lukas; Pathak, Manisha; Jach, Franziska; Koželj, Primoz; Ormeci, Alim; Höhn, Peter; Niewa, Rainer
    The first nitridogermanates(III) Ca6[Ge2N6] and Sr6[Ge2N6] were synthesized from sodium flux and structurally characterized by powder and single crystal X‐ray diffraction, respectively. They crystallize isostructurally to each other and homeotypic to Ca6[Cr2N6]H in space group R3‾. They feature unprecedented, mutually isolated, ethane‐like [GeIII2N6]12- anions in a staggered conformation. The compounds are semiconductors according to resistivity measurements and electronic structure calculations, yielding band gaps of 1.1 eV for Ca6[Ge2N6] and 0.2 eV for Sr6[Ge2N6].
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    Die reduzierten Nitridogermanate(III) Ca6[Ge2N6] und Sr6[Ge2N6] mit Ge-Ge-Bindungen
    (2021) Link, Lukas; Pathak, Manisha; Jach, Franziska; Koželj, Primoz; Ormeci, Alim; Höhn, Peter; Niewa, Rainer
    Die ersten Nitridogermanate(III) wurden in Form der Verbindungen Ca6[Ge2N6] und Sr6[Ge2N6] mithilfe von Natrium als Flussmittel synthetisiert und durch Röntgenbeugung am Pulver beziehungsweise am Einkristall charakterisiert. Ca6[Ge2N6] und Sr6[Ge2N6] kristallisieren isostrukturell zueinander und homöotyp zu Ca6[Cr2N6]H in der Raumgruppe R-3. Sie weisen neuartige, voneinander isolierte, Ethan-analoge [GeIII2N6]12--Anionen in gestaffelter Konformation auf. Widerstandsmessungen und Berechnungen der elektronischen Struktur zufolge handelt es sich um Halbleiter mit Bandlücken von 1.1 eV für Ca6[Ge2N6] und 0.2 eV für Sr6[Ge2N6].