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

Abstract

Laponite samples intercalated with <TEX>$Tb^{3+}$</TEX> or <TEX>$Tb^{3+},Ce^{3+}$</TEX> ions were prepared by exchange of Na+ ions in interlayers with <TEX>$Tb^{3+}$</TEX> or <TEX>$Ce^{3+}$</TEX> ions. Strong green and weak blue emissions under vacuum ultraviolet (VUV) excitation (<TEX>${\lambda}$</TEX> = 158 nm) were observed due to the <TEX>$^5D_4{\rightarrow}^7F_J$</TEX> and <TEX>$^5D_3{\rightarrow}^7F_J$</TEX> emission lines, respectively. <TEX>$Tb^{3+}$</TEX> ions in an interlayer of laponite mainly existed in ion pairs or clusters, as evidenced by the concentration-dependent luminescence of the <TEX>$Tb^{3+}$</TEX> ions on the relative intensities of the <TEX>$^5D_3{\rightarrow}^7F_J$</TEX> and the <TEX>$^5D_4{\rightarrow}^7F_J$</TEX> emission lines, due to the action of a cross-relaxation process. The addition of <TEX>$Ce^{3+}$</TEX> ions increased the thermal stability of <TEX>$Tb^{3+}$</TEX> intercalated laponite up to <TEX>$650^{\circ}C$</TEX> and quenched the <TEX>$^5D_3{\rightarrow}^7F_J$</TEX> emission lines, probably by promoting the formation of <TEX>$Tb^{3+}$</TEX> ion pairs at relatively low <TEX>$Tb^{3+}$</TEX> concentrations.