Luminescence characteristics of rare-earth-doped barium hexafluorogermanate BaGeF6 nanowires: fast subnanosecond decay time and high sensitivity in H2O2 detection

Abstract

Fluorides are promising host materials for optical applications. This paper reports the photoluminescent (PL) and cathodoluminescent (CL) characteristics of barium hexafluorogermanate BaGeF₆ nanowires codoped with Ce³⁺, Tb³⁺ and Sm³⁺ rare earth ions, produced by a solvothermal route. The synthesized BaGeF₆ nanowires exhibit uniform morphology and size distribution. X-ray diffraction divulges the one-dimensional growth of crystalline BaGeF₆ 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 Ce³⁺/Tb³⁺, and Ce³⁺/Tb³⁺/Sm³⁺, respectively, under a UV excitation source. The PL emission from the codoped BaGeF₆ nanowires, when excited by a 254 nm source, originates from the efficient energy transfer bridges between Ce³⁺, Tb³⁺ and Sm³⁺ 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 BaGeF₆ nanowires in the tunable visible range reveals their potential use for the detection of high-energy radiation. The PL emissions are sensitive to H₂O₂ at low concentrations, enabling their high-sensitivity detection of H₂O₂ using BaGeF₆ nanowires. A comparison with BaSiF₆ nanowires is made in terms of decay time and its sensitivity towards H₂O₂.