Preparation and crystal structural properties of Er³⁺–exchanged GTS–type sodium titanosilicate

Abstract

Powder sample of GTS–type sodium titanosilicate (Na–GTS) was prepared using a hydrothermal method. The Er³⁺–exchanged forms [Na_4(1−x)Er_4x/3Ti₄O₄(SiO₄)₃·nH₂O] of Na–GTS with the compositions up to x = 0.96 were obtained by shaking the single–phase sample of Na–GTS in the ErCl₃ aqueous solutions (25 mL, 0.01–0.5 M) at 25 and 60 °C for 6 h. The Er³⁺–exchange experiments revealed that the Er³⁺–exchange amounts (x) increase with increasing the concentration of ErCl₃ aqueous solutions and the higher treatment temperature more effectively promotes ion–exchange. Thermogravimetry–differential thermal analysis (TG–DTA) measurements showed that the exchange of Na⁺ for Er³⁺ decreases the dehydration temperature and the H₂O content. The simulation of powder X–ray diffraction (XRD) patterns suggests that Er³⁺ ions occupy both 4e and 6g sites in the assumed psuedocubic structure.