X-ray excited photoluminescence near the giant resonance in solid-solution Gd1−xTbxOCl nanocrystals and their retention upon solvothermal topotactic transformation to Gd1−xTbxF3. Issue 2 (14th December 2015)

• Record Type: Journal Article
• Authors: Waetzig, Gregory R.; Horrocks, Gregory A.; Jude, Joshua W.; Zuin, Lucia; Banerjee, Sarbajit
• Is Part Of: Nanoscale. Volume 8:Issue 2(2016)
• Page Start: 979
• Page End: 986
• Publication Date: 2015-12-14
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c5nr07819a
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : A topotactic transformation route is developed for converting Tb-incorporated GdOCl to GdF3 with preservation of the X-ray and optically stimulated luminescence. Abstract : Design rules for X-ray phosphors are much less established as compared to their optically stimulated counterparts owing to the absence of a detailed understanding of sensitization mechanisms, activation pathways and recombination channels upon high-energy excitation. Here, we demonstrate a pronounced modulation of the X-ray excited photoluminescence of Tb 3+ centers upon excitation in proximity to the giant resonance of the host Gd 3+ ions in solid-solution Gd1− x Tb x OCl nanocrystals prepared by a non-hydrolytic cross-coupling method. The strong suppression of X-ray excited optical luminescence at the giant resonance suggests a change in mechanism from multiple exciton generation to single thermal exciton formation and Auger decay processes. The solid-solution Gd1− x Tb x OCl nanocrystals are further topotactically transformed with retention of a nine-coordinated cation environment to solid-solution Gd1− x Tb x F3 nanocrystals upon solvothermal treatment with XeF2 . The metastable hexagonal phase of GdF3 can be stabilized at room temperature through this topotactic approach and is transformed subsequently to the orthorhombic phase. The fluoride nanocrystals indicate an analogous but blue-shifted modulation of the X-ray excited optical luminescence of the Tb 3+ centers upon X-ray excitation near the giant resonance of the host Gd 3+ ions.