A new ternary oxide was synthesized from Yb2O3, TiO2 and MnO in an Ar atmosphere containing 1% H-2 at 1523K, The compound was characterized using a powder X-ray diffractometer (XRD), an electron probe microanalyzer (EPMA), and a transmission electron microscope (TEM), The oxide with the composition, Yb1.8Ti1.3Mn0.7O6.0 had a hexagonal cell with lattice parameters a = 0.6137(1) nm and c = 1.1794(2) nm, The nonstoichiometric oxide was unstable following electron irradiation, The electron beam irradiation for 3-20 minutes changed the structure of the oxide. The selected area electron diffraction (SAD) patterns showed the changes, in which superlattice reflections vanished or new extra reflections appeared. The changed material had a domain structure composed of two types of structures, one structure had a basic cell with the a/3 dimension and the other one had a new structure with the 2a/root3 dimension.