Crystal structure and X-ray luminescence of zeolite Y (Si/Al = 1.69) containing extraframework hafnium(IV)

Abstract Hafnium(IV) was introduced into zeolite Y by allowing anhydrous Cs,Na–Y (|Cs 43 Na 28 |[Si 121 Al 71 O 384 ]-FAU) to react with HfCl 4 ( g , 3.2 × 10 3  Pa) at 503 K for 48 h. The crystal structures of Cs,Na–Y and of the product, Hf,Cl,Cs,Na–Y (|(HfCl) 1.5 (NaCl) 4.5 Cs 43 Na 23.5 |[Si 121 Al 71 O 384 ]-FAU), were determined by single-crystal crystallography at 293 K using synchrotron X-radiation. They were refined in the space group Fd 3 ¯ m ( a  = 24.808(1) A and 24.735(1) A) with all unique data to the final error indices R 1  = 0.062 and 0.067 for the 1572 and 1413 reflections for which F o  > 4σ( F o ), respectively. Their compositions were confirmed by energy-dispersive X-ray analyses. The Hf 4+ ions occupy 6-rings in the supercages; each is tetrahedral with three bonds to 6-ring oxygen atoms and one to a Cl − ion. Per unit cell, 4.5 Na + ions do that also. The remaining Na + and Cs + ions occupy well established cation positions near 6- and 12-rings. The sky-blue X-ray induced luminescence spectrum of Hf,Cl,Cs,Na–Y is a broad band from 300 to 650 nm with peaks at 380 nm and 490 nm. This luminescence is blue-shifted compared to that of zeolite Hf,Cl,Cs,Na-A.