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Ammonothermal Synthesis and Crystal Structure of the Nitridoalumogermanate Ca 1– x Li x Al 1– x Ge 1+ x N 3 ( x ≈ 0.2)
Author(s) -
Häusler Jonas,
Eisenburger Lucien,
Oeckler Oliver,
Schnick Wolfgang
Publication year - 2018
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201701314
Subject(s) - chemistry , orthorhombic crystal system , crystallography , band gap , crystal structure , analytical chemistry (journal) , superstructure , spectroscopy , rietveld refinement , absorption spectroscopy , x ray crystallography , diffraction , materials science , optics , oceanography , physics , optoelectronics , chromatography , quantum mechanics , geology
The new nitridoalumogermanate Ca 1– x Li x Al 1– x Ge 1+ x N 3 ( x ≈ 0.2) was synthesized from supercritical ammonia at 925 K and 185 MPa starting from the intermetallic precursor Ca 3 Al 2 Ge 2 and Li as mineralizer. The crystal structure was refined by the Rietveld method; Ca 1– x Li x Al 1– x Ge 1+ x N 3 with x ≈ 0.2 [ a = 9.9822(5), b = 5.7763(2), c = 5.1484(1) Å, Z = 4, R wp = 0.0492] crystallizes in orthorhombic space group Cmc 2 1 (no. 36). Needle‐shaped crystals with up to 15 µm in length were detected by scanning electron microscopy. Possible cation ordering was analyzed by transmission electron microscopy. No superstructure reflections were observed in electron diffraction patterns and the structure model was confirmed by Z‐contrast imaging. The composition was verified by energy‐dispersive X‐ray spectroscopy on single crystals and inductively coupled plasma optical emission spectrometry. Optical properties were studied by diffuse reflectance spectroscopy, showing a broad absorption band between 250 and 300 nm. The optical band gap was estimated to be 4.3 eV at room temperature using the Tauc method.