“…ZrO 2 exists in three different phases namely room temperature stable monoclinic phase and high temperature stable tetragonal and cubic phases (metastable phases at room temperature). The metastable phase of zirconia (t-ZrO 2 ) is the focus of recent investigations due to their high hardness, chemical inertness and optical properties (Abbe number ≈ 35) make them important target materials for the fabrication of metal-halide lamps, solid state lasers, scintillators and bar-code scanners [3][4][5][6]. Recently, t-ZrO 2 has been proved to be a highly luminescent material, which is photochemically stable with low phonon energy (470 cm −1 ) [7].…”