  The magnetic properties of Ba3TiRu2O9 , whose crystal structure is based on
stacked triangular planar lattices of MO6 dimers and single MO6 octahedra, are
reported. The system is magnetically disturbed by a substantial amount of Ti/Ru
chemical disorder. The Weiss temperature and effective magnetic moment were
found to be -29.5 K and 1.82 {\mu}B/f.u. respectively, and a bifurcation in the
zero field cooled and field cooled magnetic susceptibility is observed below
4.7 K, suggesting that this is a compositionally-disordered spin-glass system.
The material is a semiconductor with an activation energy for charge transport
of approximately 0.14 eV.
