Barium fluoride hollow microcubes: hydrothermal synthesis and host for lanthanide near-infrared luminescent properties

Abstract

In this work, we report a simple one-pot approach to prepare hollow BaF₂ microcubes employing the reaction of Ba(NO₃)₂ and NaBF₄ under hydrothermal conditions. X-Ray diffraction, scanning electron microscopy, electron diffraction, transmission electron microscopy, and photoluminescence spectra were used to characterize the samples. Contrast experiments indicated that the triblock copolymer of EO₂₀PO₇₀EO₂₀ (P123) and the complex of citrate both played important roles for the formation of hollow BaF₂ cubes. Furthermore, the use of NaBF₄ as fluoride source is indispensable for obtaining the microstructures. For the first time, we demonstrate that microcubes of BaF₂ with hollow interiors can be synthesized via a combination of soft-templating mechanism and oriented attachment process. Additionally, the near-infrared luminescence of lanthanide ions (Er, Nd, and Yb) doped BaF₂ hollow microcubes were discussed in detail.