THE CRYSTAL-STRUCTURE OF KGAO2 AND NAGAO2(II)

By annealing intimate mixtures of K2O, Na2O and beta-Ga2O3 (K : Na : Ga = 2.2 : 1.1 : 1) we obtained single crystals of K2Na4[(GaO3)2] and KGaO2 (Ag-cylinder; 600-degrees-C, 26 d). Structure refinement for KGaO2 (four-circle diffractometer data, Mo-K-alphaBAR, 1390 of 1390 I(o)(hkl); R = 5.55%, R(w) = 3.05%) confirms the spacegroup Pbca; a = 552.1 pm, b = 1107.5 pm, c = 1580.7 pm, Z = 16. According to K[GaO4/2] We have a stuffed cristobalite-related structure. Single crystals of NaGaO2(II) were grown by annealing intimate mixtures of Na2O2 and GaAs (Na2O2 : GaAs 4.1 : 1) in Ag-cylinders that were not completely closed (570-degrees-C, 6 weeks). Structure refinement for NaGaO2(II) (four-circle diffractometer data, Mo-K-alphaBAR, 588 of 616 10(hkl); R = 4.54%, R(w) = 4.06%) confirms the spacegroup Pna2(1); a = 549.8(1)pm, b = 720.6(1) pm, c = 529.8(1) pm, Z = 4. In NaGaO2(II) we have a wurtzite-related structure.