Encapsulating Luminescent Materials in Zeolites. III. Crystal Structure and Scintillation Properties of Cs,Na-LTA Treated with Zirconium Chloride Vapor

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• 作者：Chung Woo Lee ; Joon Young Kim ; Hong Joo Kim ; Nam Ho Heo ; Karl Seff
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：August 25, 2016
• 年：2016
• 卷：120
• 期：33
• 页码：18682-18693
• 全文大小：694K
• 年卷期：0
• ISSN：1932-7455

文摘

With the purpose of developing a new zeolite scintillator, fully dehydrated Cs,Na-A was exposed to ZrCl<sub>4sub> (g, 3.7 × 10<sup>3sup> Pa) at 523 K. The crystal structures of Cs,Na-A and of the product, |Zr<sub>0.14sub>Cs<sub>5.69sub>Na<sub>4.13sub>Cl<sub>0.85sub>|[Si<sub>12sub>Al<sub>12sub>O<sub>48sub>]-LTA (Zr,Cs,Na,Cl-A), were determined by single-crystal crystallography using synchrotron X-radiation. The structure of Zr,Cs,Na,Cl-A was refined in the space group Pm3̅m (a = 12.230(1) Å) with all unique data to the final error index R<sub>1sub> = 0.069 for the 639 reflections for which F<sub>osub> > 4σ(F<sub>osub>). Its composition was confirmed by scanning electron microscopy energy-dispersive X-ray analysis (SEM-EDX). Octahedral ZrCl<sub>6sub><sup>2–sup> ions center 14% of the large cavities; each Cl<sup>–sup> ion bonds to an 8-ring Cs<sup>+sup> ion. These Cs<sup>+sup> ions bridge between ZrCl<sub>6sub><sup>2–sup> ions to form a continuum with unit cell formula Cs<sub>3sub>ZrCl<sub>6sub><sup>+sup> in the near-surface volume of the crystal. Other Cs<sup>+sup> ions lie opposite 6-rings in the sodalite and large cavities; Na<sup>+sup> ions occupy the remaining 6-rings. Upon X-irradiation, Zr,Cs,Na,Cl-A luminesces bright sky blue; the emission band is broad, ranging from 370 to 750 nm, peaking at 480 nm. The integrated intensity of the emission is ca. 16 times greater than that of anthracene, a well documented scintillator. This intense luminescence appears to result from charge transfer within the ZrCl<sub>6sub><sup>2–sup> ions.