Tb³⁺ and Ce³⁺ Intercalated Laponite Powder: The Influence of Ce³⁺ Ions on Thermal Stability and Optical Properties of Tb³⁺ Intercalated Laponite

Laponite samples intercalated with Tb³⁺ or Tb³⁺,Ce³⁺ ions were prepared by exchange of Na⁺ ions in interlayers with Tb³⁺ or Ce³⁺ ions. Strong green and weak blue emissions under vacuum ultraviolet (VUV) excitation (λ = 158 nm) were observed due to the ⁵D₄→⁷F_J and ⁵D₃→⁷F_J emission lines, respectively. Tb³⁺ ions in an interlayer of laponite mainly existed in ion pairs or clusters, as evidenced by the concentration-dependent luminescence of the Tb³⁺ ions on the relative intensities of the ⁵D₃→⁷F_J and the ⁵D₄→⁷F_J emission lines, due to the action of a cross-relaxation process. The addition of Ce³⁺ ions increased the thermal stability of Tb³⁺ intercalated laponite up to 650 .deg. C and quenched the ⁵D₃→⁷F_J emission lines, probably by promoting the formation of Tb³⁺ ion pairs at relatively low Tb³⁺ concentrations