Synthesis and Crystal Structures of InGaO₃(ZnO)_m (m = 2 and 3)

Isabelle Keller (1) , Wilfried Assenmacher (1) , Gregor Schnakenburg (1) , Werner Mader (2)

1 Institut für Anorganische Chemie
2 Institut für Anorganische Chemie [Bonn]

An optimized high temperature route in sealed platinum tubes was used for synthesis of pure powders of members of the homologues series InGaO3(ZnO)m. Single crystals of InGaO3(ZnO)2 were grown from a K2MoO4 flux. InGaO3(ZnO)2 crystallises in the hexagonal crystal system (P63/mmc; No. 194), deduced from convergent beam electron diffraction (CBED). Single crystal structure refinement from XRD data (a = 3.2909(2) Å; c = 22.485(2) Å; Z = 2; 1603 data, R1 = 0.0237) revealed a compound which consist of an alternate stacking of and corresponding to CdI2 and wurtzite type structure motifs, respectively. Inversions of the ZnO4 tetrahedra occurs (i) at the InO6 octahedral layer and (ii) halfway in the wurtzite type region where the inversion boundary is built by Ga3+ in trigonal bipyramidal co-ordination with a long Ga-Oapical distance of 2.138 Å. The site occupation of Zn2+ and Ga3+, respectively, was confirmed by valence sum calculations. The structure of InGaO3(ZnO)3 was refined from powder X-ray diffraction data. InGaO3(ZnO)3 crystallises trigonal (R3¯m; No. 166; a = 3.2871(9) Å; c = 41.589(1) Å, RBragg = 0.0506). The space group was confirmed by CBED. The structure of InGaO3(ZnO)3 is similar to InGaO3(ZnO)2, however, the wurtzite type part of the structure has an even number of closed packed oxygen layers and thus the inversion boundary within this area is different. The compounds described here have the structural charactistics as other known members with general formula (ARO3)·(ZnO)m) with m = integer.

Mots clés: Physical Sciences

Isabelle Keller, Wilfried Assenmacher, Gregor Schnakenburg, Werner Mader. Synthesis and Crystal Structures of InGaO₃(ZnO)_m (m = 2 and 3). Journal of Inorganic and General Chemistry / Zeitschrift für anorganische und allgemeine Chemie, 2009, 635 (12), pp.2065. ⟨10.1002/zaac.200900199⟩. ⟨hal-00509230⟩