Thermal loading induced near-infrared broadband upconversion emission of Sm3+-doped β-NaYbF4 nano-phosphors

A non-closed hydrothermal synthetic processing is improved to synthesize Sm3+ doped beta-NaYbF4 nano-phosphors at 98 degrees C without any high-temperature and high-pressure treatments as a final step. Novel green, red, and near-infrared broadband (799-873 nm) upconversion emissions of Sm3+-doped beta-NaYbF4 nano-phosphors under 980 nm excitation are observed. These UC emissions can be assigned to the Sm3+ transitions of (4)G(j), F-4(3/2) and F-6(11/2)-> H-6(j). The half-width of 873 nm emission band is broadened nearly two-fold through the annealing treatment for nano-phosphors. The upconversion process in Yb3+-Sm3+ system is discussed based on energy transfer mechanisms. (C) 2011 Elsevier B.V. All rights reserved.