Luminescence characteristics of rare-earth-doped barium hexafluorogermanate BaGeF(6) nanowires: fast subnanosecond decay time and high sensitivity in H(2)O(2) detection

Fluorides are promising host materials for optical applications. This paper reports the photoluminescent (PL) and cathodoluminescent (CL) characteristics of barium hexafluorogermanate BaGeF(6) nanowires codoped with Ce(3+), Tb(3+) and Sm(3+) rare earth ions, produced by a solvothermal route. The synthesized BaGeF(6) nanowires exhibit uniform morphology and size distribution. X-ray diffraction divulges the one-dimensional growth of crystalline BaGeF(6) structure, with the absence of any impurity phases. Visible luminescence is recorded from the nanowires in green and red regions, when the nanowires are codoped with Ce(3+)/Tb(3+), and Ce(3+)/Tb(3+)/Sm(3+), respectively, under a UV excitation source. The PL emission from the codoped BaGeF(6) nanowires, when excited by a 254 nm source, originates from the efficient energy transfer bridges between Ce(3+), Tb(3+) and Sm(3+) ions. The decay time of the visible luminescent emission from the nanowires is in the order of subnanoseconds, being one of the shortest decay time records from inorganic scintillators. The CL emission from the BaGeF(6) nanowires in the tunable visible range reveals their potential use for the detection of high-energy radiation. The PL emissions are sensitive to H(2)O(2) at low concentrations, enabling their high-sensitivity detection of H(2)O(2) using BaGeF(6) nanowires. A comparison with BaSiF(6) nanowires is made in terms of decay time and its sensitivity towards H(2)O(2).