Synthesis, crystal structure and charge distribution of InGaZnO4. X-ray diffraction study of 20kb single crystal and 50kb twin by reticular merohedry

Synthesis of InGaZnO4 at 20Kb and 50Kb produced a single crystal and a twin ned crystal respectively. The X-ray diffraction crystal structure refinemen t (R1 = 0.015 and 0.019 respectively) and the Charge Distribution analysis are reported. Space group is R (3) over bar m; cell parameters in hexagonal axes are a = 3.2990(2)Angstrom, c = 26.1013(25)Angstrom (20kb single cryst al) and a = 3.3051(2)Angstrom, c = 26.1029(19)Angstrom (50kb twinned crysta l). The cell volume is 246.01(3)Angstrom(3) and 246.94(3)Angstrom(3) respec tively. The In is in regular octahedral coordination, whereas Ga/Zn are in trigonal bipyramid co-ordination. Charge Distribution on cations (2.94 and 2.95 respectively vs. 3.0 for In, and 2.53 vs. 2.5 for Ga/Zn) shows that th e structure is well refined. Charge Distribution on oxygens (-1.96 and -2.0 4 for O1 and O2, vs. -2.0) excludes the presence of valence unbalance effec ts. A possible structural role of the trigonal bipyramidal coordination is discussed.