Hydrothermal synthesis of 4ZnO·B2O3·H2O:Ln3+ (Ln=Eu, Tb) phosphors: Morphology-tunable and luminescence properties.

4ZnO·B2O3·H2O:Ln3+ (Ln=Eu, Tb) phosphors with different morphologies have been successfully synthesized via one-step hydrothermal method through regulating the molar amount of Eu3+ and Tb3+. Comprehensive scanning electron microscopy (SEM), X-ray diffraction (XRD) Fourier transform infrared spectrum (FT-IR) and inductively coupled plasma atomic emission spectrometer (ICP-AES) characterizations all confirm that obtained products are 4ZnO·B2O3·H2O:Ln3+ (Ln=Eu, Tb). The experimental results displayed that the morphology and photoluminescence of compounds is regularly changed with increased the molar amount of rare earth ions. For the Eu3+-doped, Tb3+-doped and Eu3+/Tb3+ co-doped 4ZnO·B2O3·H2O phosphors of morphologies, the rod-like structures gradually changed to flower-like structures, fine wire-like structure and hybrid structure, respectively. To their photoluminescence, the Eu3+ shows a red emission (615nm); the Tb3+ shows a green emission (545nm); for the Eu3+/Tb3+ co-doped 4ZnO·B2O3·H2O phosphors, a combination of blue (5d-4f of Eu2+), green (5D4-7F5 of Tb3+) and red (5D0-7F2 of Eu3+) emissions emerges to achieve white emission. In addition, the energy transfer among Eu3+, Eu2+ and Tb3+ ions was also discussed.