The incorporation of alkali cations into the tunneled structure of Ga4TiO8 was investigated and compared to predictions based on atomistic computer simulations. Samples were prepared as A(x)Ga(4-x)Ti(1-x)O(8), A=Li, Na, and K, x <= 0.7, and as NaxGa4+xTi2-xO8, (x=0.7, 0.85, and 1.0) using solid-state reactions at 1050-1350 degrees C. The sodium-containing tunneled structure, NaxGa4-xTi1-xO8, formed via solid-state reaction, but the potassium and lithium analogs did not. Instead, these systems formed mixed-phase assemblages, which are discussed in reference to compatibility triangles in the Li2O-Ga2O3-TiO2 and K2O-Ga2O3-TiO2 systems. Experimental results were compared to the results of energy minimization calculations using the General Utility Lattice Program (GULP). For the lithium-containing system, the computer simulations correctly predicted the formation of a mixed-phase assemblage containing LiGa5O8, Ga2O3, and TiO2. For the sodium- and potassium-containing system, the computer simulations suggested that mixtures of the single-cation oxide components should be the stable phase assemblages, in contradiction with experimentally observed results. Energy minimization calculations conducted on structurally different NaxGa4+xTi2-xO10 and NaxGa4+xTi3-xO12 phases indicated that those based on the n = 6 and n = 7 beta-gallia rutile intergrowth structures have lower lattice energies than the experimentally observed sodium titanogallate structures reported previously in literature. (c) 2005 Elsevier B.V. All rights reserved.