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Title: Synthesis and crystal structure characterization of InGaZnO{sub 4} with a new defect structure

Single crystals of InGaZnO{sub 4} were synthesized in a sealed Pt-tube at elevated temperatures under normal pressure without flux. InGaZnO{sub 4} has a trigonal crystal system (R3{sup ¯}m; No. 166) deduced from convergent beam electron diffraction (CBED). Single crystal structure refinement from XRD data at −150 °C (a=3.275(1) Å; c=25.99(1) Å; Z=3) revealed an alternate stacking of InO{sub 6/3}{sup −} and (Ga,Zn)O{sub 4/4}{sup +} layers, iso-structural to YbFe{sub 2}O{sub 4}. The cell parameters at room temperature were refined from powder X-ray diffraction data (a=3.284(3) Å and c=26.037(3) Å). The transparent crystals have a gray-bluish color and exhibit an excess of Ga expressed by the cation ratio of In:Ga:Zn=30.2(9):39(1):31(1) determined by energy dispersive X-ray spectroscopy (EDXS). While the isovalent substitution of In{sup 3+} by Ga{sup 3+} is known, an additional aliovalent substitution of Zn{sup 2+} by Ga{sup 3+} is observed. This results in the formula (In{sub 0.9}Ga{sub 0.1})Ga{sub 1.06}Zn{sub 0.91}□{sub 0.03}O{sub 4} where 3% of the cations in 4+1 coordination are vacant due to aliovalent substitution. Further evidence of that defect structure is found in the lattice parameter a which is substantially smaller than in stoichiometric InGaZnO{sub 4}, as well as in the strong absorption in the near-IR from transitions correlatedmore » with the defect structure. The bluish color of the crystals is due to an enhanced absorption in the red of the visible spectrum. For the first time, we achieved to image InGaZnO{sub 4} at atomic resolution in the electron microscope proving a perfect periodic stacking of atomic layers. - Graphical abstract: Single crystals of InGaZnO{sub 4} have been synthesized at ambient pressure and analyzed with X-ray diffraction, electron microscopy, and optical absorption. Optical band gap and optical transmission have been determined. - Highlights: • Preparation of single crystals of InGaO{sub 3}(ZnO){sub 1} at ambient pressure for the first time. • Non-stoichiometric compound (In{sub 0.9}Ga{sub 0.1})Ga{sub 1.06}Zn{sub 0.91}□{sub 0.03}O{sub 4} with defect structure, excess of Ga, depletion of Zn. • Real structure of InGaO{sub 3}(ZnO){sub 1} imaged by high resolution TEM for the first time. • Optical band gap and transmission of InGaO{sub 3}(ZnO){sub 1} single crystal.« less
Authors:
 [1] ;  [2] ;  [3] ;  [3] ;  [4] ;  [2]
  1. Institute for Inorganic Chemistry, University of Bonn, Römerstr. 164, 53117 Bonn (Germany)
  2. Institute for Inorganic Chemistry, University of Bonn, Roömerstr. 164, 53117 Bonn (Germany)
  3. National Institute for Materials Science (NIMS), Namiki, Tsukuba, Ibaraki 305-0044 (Japan)
  4. Department of Chemical Engineering and Materials Science, Yuan Ze University, 135, Yuan-Tung Road, Chung-Li, Taoyuan 32003, Taiwan (China)
Publication Date:
OSTI Identifier:
22334278
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 215; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION; CATIONS; CRYSTAL DEFECTS; ELECTRON BEAMS; ELECTRON DIFFRACTION; GALLIUM IONS; INDIUM IONS; INDIUM OXIDES; LATTICE PARAMETERS; MONOCRYSTALS; POWDERS; SYNTHESIS; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY; ZINC IONS; ZINC OXIDES