, respectively, was confirmed by valence sum calculations. The structure of InGaO 3 (ZnO) 3 was refined from powder X-ray diffraction data. InGaO 3 (ZnO) 3 crystallises trigonal (R 3;¯m; No. 166; a = 3.2871(9) Å; c = 41.589(1) Å, R Bragg = 0.0506). The space group was confirmed by CBED. The structure of InGaO 3 (ZnO) 3 is similar to InGaO 3 (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 (ARO 3 )·(ZnO) m ) with m = integer.