Ag-catalyzed synthesis of europium borate Eu(BO2)3 nanowires, growth mechanism and luminescent properties

Eu(BO2)3 nanowires with diameters of 10-20 nm were fabricated through direct sintering Eu(NO3)3·6H2O and H3BO3 with Ag as catalyst. The result of X-ray diffraction (XRD) indicated that the nanowire was single-crystalline with body-centered monoclinic structure. Based on the fact that Ag nanoparticles attached to the tips and middles of nanowires, a vapor-liquid-solid (VLS) growth mechanism of the Eu(BO2)3 nanowires is proposed. Three well-defined stages have been clearly identified during the process: Ag-Eu-B-O cluster process, crystal nucleation, and axial growth. The photoluminescence characteristics under UV excitation were investigated. The dominated Eu3+ orange-red emission corresponding to the magnetic dipole transition 5D0 → 7F1 is centered at 591 nm, indicating that Eu3+ is located at high symmetry crystal field with inversion center.