Crystal growth and optical properties of TbM3(BO3)4 (M=Al, Ga) crystals

$\mathrm{TbGa}_{3}\left(\mathrm{BO}_{3}\right)_{4}$ and $\mathrm{TbAl}_{3}\left(\mathrm{BO}_{3}\right)_{4}$ crystals were grown using the $\mathrm{Bi}_{2} \mathrm{Mo}_{3} \mathrm{O}_{12}: \mathrm{B}_{2} \mathrm{O}_{3}: \mathrm{Tb}_{2} \mathrm{O}_{3}$ and $\mathrm{K}_{2} \mathrm{Mo}_{3} \mathrm{O}_{10}: \mathrm{B}_{2} \mathrm{O}_{3}: \mathrm{Tb}_{2} \mathrm{O}_{3}$ flux, respectively. The produced compounds crystallize in the R32 space group. A strong green emission of the luminescence is primarily dominated by the ${ }^{5} \mathrm{D}_{4}$ to ${ }^{7} F_{5}$ transition in $\mathrm{Tb}^{3+}$. According to the data obtained, the SHG efficiency is higher for the $\mathrm{TbGa}_{3}\left(\mathrm{BO}_{3}\right)_{4}$ compound due to its higher molar mass.