Fabrication of Eu³⁺ and Sm³⁺ Codoped Micro/Nanosized MMoO₄ (M = Ca, Ba, and Sr) via Facile Hydrothermal Method and Their Photoluminescence Properties through Energy Transfer

Abstract

Eu 3+ and Sm 3+ codoped micro/nanosized MMoO 4 (M = Ca, Ba, Sr) phosphors with various shapes have been synthesized via a facile hydrothermal method with surfactant-free environment. The morphology of the materials was found to be manipulated by the pH value of the precursor solution. MMoO 4:Eu 3+, Sm 3+ (M = Ca, Ba, Sr) nanoflakes, microflowers, cubes, and spheres were obtained and characterized by X-ray diffraction and field emission scanning electron microscopy. The luminescent properties of the molybdate phosphors were systematically studied. The introduction of Sm 3+ into each of the red-emitting phosphors MMoO 4:Eu 3+ (M = Ca, Ba, Sr) can generate a strong excitation line at 405 nm, originating from the 6 H 5/2 → 6 P 5/2 transition of Sm 3+, significantly extending the excitation region for matching the near-ultraviolet light-emitting diodes (∼400 nm). Energy transfer from Sm 3+ to Eu 3+ was observed in the whole MMoO 4 systems and investigated in detail in CaMoO 4 as a function of Sm 3+ concentrations. A back-energy transfer was also evidenced by the shortening of the 5 D 0 lifetimes of Eu 3+ with increasing Sm 3+ concentrations.