Low-temperature synthesis of NaRE(WO4)2 films via anion exchange from layered rare-earth hydroxides (LRHs) films, phase/morphology evolution and photoluminescence

摘要

Films of alkaline lanthanide tungstates, NaRE(WO4)(2) (RE = La-Ho, and Y), were hydrothermally synthesized via an anion exchange using electrodeposited layered rare-earth hydroxide (RE2(OH)(5)NO3 center dot nH(2)O) films as precursor templates in the presence of excess Na2WO4 at pH similar to 10 and 100 degrees C, without further heat treatment. The crystal structures and photoluminescence of the materials were characterized by XRD, FT-IR, FE-SEM, TEM, and PLE/PL spectroscopy techniques. The evolution of the phase composition and particle morphology from La-2(OH)(5)NO3 center dot nH(2)O to NaLa(WO4)(2) was unveiled by varying the reaction time. With the successful synthesis of NaRE(WO4)(2) for the wide range of REs, the effects of lanthanide contraction on the structural features and morphology of the NaRE(WO4)(2) films were also clarified. Additionally, the photoluminescence of the NaEu(WO4)(2) and NaTb(WO4)(2) films were investigated, and they exhibited strongly red and green emissions, respectively. To the best of our knowledge, the layered rare-earth hydroxides have not been utilized as precursors to synthesize NaRE(WO4)(2) films, and this work might have wide implications for the generation of other types of inorganic functional films.

关键词