Luminescence of $Ce^{3+}$ -doped aluminoborates, $M_3Al_6B_8O_{24}$ (M = Mg, Ca, Sr, Ba)

Newer dielectric materials doped with appropriate impurities are often sought for tunable blue laser applications. Thus, the luminescence properties of $Ce^{3+}$ in the novel ternary borates, $M_3Al_6B_8O_{24}$ (M = Mg, Ca, Sr, Ba) have been investigated. The single excitation band centred around 310 nm and the broad emission band maximising around 400 nm are devoid of the characteristic $Ce^{3+}$ doublet and the vibrational fine structures, even at low temperatures. These luminescence features are due to the extensive crystal-field splitting of the 4f ground state. The large Stokes shift of $\sim7000cm^{-1}$ and the half-band-widths are influenced by $M^{2+}$ ions