Browsing by Author "Link, Lukas"

Filter results by typing the first few letters
Now showing 1 - 4 of 4
  • Thumbnail Image
    ItemOpen Access
    Diversity of strontium nitridogermanates(IV) : novel Sr4[GeN4], Sr8Ge2[GeN4], and Sr17Ge2[GeN3]2[GeN4]2
    (2020) Link, Lukas; Niewa, Rainer
    Single crystals of three new strontium nitridogermanates(IV) were grown in sealed niobium ampules from sodium flux. Dark red Sr4[GeN4] crystallizes in space group P21/c with a = 9.7923(2) Å, b = 6.3990(1) Å, c = 11.6924(3) Å and β = 115.966(1)°. Black Sr8Ge2[GeN4] contains Ge4- anions coexisting with [GeIVN4]8- tetrahedra and adopts space group Cc with a = 10.1117(4) Å, b = 17.1073(7) Å, c = 10.0473(4) Å and β = 115.966(1)°. Black Sr17Ge6N14 features the same anions alongside trigonal planar [GeIVN3]5- units. It crystallizes in P1 with a = 7.5392(1) Å, b = 9.7502(2) Å, c = 11.6761(2) Å, α = 103.308(1)°, β = 94.651(1)° and γ = 110.248(1)°.
  • Thumbnail Image
    ItemOpen Access
    Polynator : a tool to identify and quantitatively evaluate polyhedra and other shapes in crystal structures
    (2023) Link, Lukas; Niewa, Rainer
    Polynator is a Python program capable of identifying coordination polyhedra, molecules and other shapes in crystal structures and evaluating their distortions. Distortions are quantified by fitting the vertices of a model to a selected set of atoms. In contrast to earlier programs, models can be deformable, which allows them to represent a point group or a range of shapes such as the set of all trigonal prisms, rather than a specific, rigid shape such as the equilateral trigonal prism. The program comes with a graphical user interface and is freely available. This paper discusses its working principle and illustrates a number of applications.
  • Thumbnail Image
    ItemOpen Access
    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].
  • Thumbnail Image
    ItemOpen Access
    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].