Synthesis, crystal structure and photoluminescence of Eu³⁺ or Tb³⁺ doped solid solutions (Y_1-xRE_x)₄S₃(Si₂O₇)

Y₄S₃(Si₂O₇) and its solid solutions (Y_1-xRE_x)₄S₃Si₂O₇ (RE = Eu x = 0.010–0.085, RE=Tb x = 0.010–0.500) were quantitatively prepared by reaction of starting compounds in molten CsCl. Single crystal X-Ray analysis revealed the difference in preference Eu³⁺ occupancy for two independent RE-sites coming from volume difference of these sites. This effect is negligible for the Tb-containing solid solution due to smaller difference in radii Tb³⁺ and Y³⁺ ions. Tb³⁺-containing samples are luminescent with typical emission of Tb³⁺, while Eu³⁺-containing samples are not luminescent. The 1%Tb³⁺-containing sample emits in blue or in green color depending on the excitation wavelength. Measured melting points are 1545 ± 15 °С for all investigated samples (Y_1-xRE_x)₄S₃Si₂O₇.