Dicarboxylate mediated efficient morphology/phase tailoring of YPO4:Ln3+ crystals and investigation of down-/up-conversion luminescence?

CrystEngComm Pub Date: 2017-08-03 DOI: 10.1039/C7CE01248A

Abstract

The dicarboxylate anions of tartrate (C4H4O62?, Tar2?), malate (C4H4O52?, Mal2?), and succinate (C4H4O42?, Suc2?) were originally used as morphology/structure modifiers in the hydrothermal crystallization of YPO4, and both hexagonal (h-) and tetragonal (t-) structured crystals with multiform morphologies of high uniformity were selectively synthesized. The materials were characterized by the combined techniques of XRD, FE-SEM, TEM, FT-IR, TG, and optical spectroscopy, and the mechanisms of phase/morphology evolution were expatiated. It was clearly shown that Tar2? may induce an inverse phase transformation of YPO4 from the thermodynamically stable tetragonal structure (nanoparticles) to the metastable hexagonal structure (microprisms), and a series of controlled experiments exhibited that the performance of Tar2? was strongly affected by the experimental parameters of Tar2?/PO43?/Y3+ molar ratio, solution pH, hydrothermal temperature, and reaction time. In comparison with Tar2?, Mal2? induced the direct crystallization of h-YPO4 microprismatic crystals while Suc2? restricted the 1-D growth of t-YPO4 nanocrystals. For the samples calcined at 700 °C, the down-conversion photoluminescence of Eu3+ in h-YPO4 and t-YPO4 and the up-conversion luminescence of the (Yb/Er)3+ couple in t-YPO4 were also comparatively studied and elucidated in detail.

Graphical abstract: Dicarboxylate mediated efficient morphology/phase tailoring of YPO4:Ln3+ crystals and investigation of down-/up-conversion luminescence
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