Spectral characteristics and energy transfer Ce$^{3+}$ $\to$ Tb$^{3+}$ $\to$ Eu$^{3+}$ in LuBO$_3$(Ce, Tb, Eu) compound

The structure, IR, luminescence, and luminescence excitation spectra of Ce$^{3+}$, Tb$^{3+}$, and Eu$^{3+}$ ions in Lu$_{1-2x}$Ce$_x$Eu$_x$BO$_3$ and Lu$_{0.91-2x}$Ce$_x$Tb$_{0.09}$Eu$_x$BO$_3$ solid solutions were studied. The minimum “threshold” distance between Ce$^{3+}$ и Eu$^{3+}$ ions was estimated, at which there is no charge transfer between these ions, leading to the quenching of Ce$^{3+}$ and Eu$^{3+}$ luminescence. It is shown that in Lu$_{0.91-2x}$Ce$_x$Tb$_{0.09}$Eu$_x$BO$_3$ compounds, the range of Ce and Eu concentrations of 0.2–0.25 at.% is optimal for obtaining the maximum luminous intensity of this compound.