Well-defined octahedral Sm³⁺, Dy³⁺ doped NaGd(MoO₄)₂ microcrystals: facile hydrothermal synthesis and luminescence properties

Well-defined NaGd(MoO₄)₂ octahedral microcrystals with singly-doped Sm³⁺ or Dy³⁺ ions and co-doped Sm³⁺/Dy³⁺ ions were prepared through a mild hydrothermal route without any additives. The as-synthesized products were characterized by means of powder X-ray diffraction, scanning electron microscopy and luminescence spectra. It was found that the pH value of the initial solution played a crucial role in determining the morphology, size and emission intensity of final products. The possible formation mechanism for the product with uniform octahedral morphology was investigated and discussed according to the time-dependent experiments. Furthermore, under near-UV excitation, NaGd(MoO₄)₂:Sm³⁺ and NaGd(MoO₄)₂:Dy³⁺ phosphors exhibited the characteristic emissions of Sm³⁺ and Dy³⁺, respectively. Meanwhile, Dy³⁺ could effectively transfer the excitation energy to Sm³⁺ under near-UV excitation when they were co-doped in NaGd(MoO₄)₂ host. Moreover, the CIE color coordinates of NaGd(MoO₄)₂: 0.05Dy³⁺, xSm³⁺ samples were located in white light region suggesting that the as-synthesized phosphors might be promising candidates in the fields of white light diodes, full-color displays and optoelectronic devices.