To exploit the potential applications of thermal neutron detection, yttrium aluminum garnet co-doped with 1 mol% Ce3+ and 5 mol% Li+ was vacuum sintered into a transparent ceramic through solid-state reaction. The transmittance of a 2 mm thick sample was measured to be as high as 80.3% in the visible range and the microstructural characterization indicated that Li ions could also act as a sintering aid. Excitation and emission spectra data further supported the assumption that the Li ions have substituted into the garnet lattice. Excitation and emission spectra data of the prepared ceramic were also obtained for use in the characterization of optical properties.