Al2O3:Cr3+ microfibers by hydrothermal route: Luminescence properties
Abstract Uniform Al 2 O 3 :Cr 3+ microfibers were synthesized by using a hydrothermal route and thermal decomposition of a precursor of Cr 3+ doped ammonium aluminum hydroxide carbonate (denoted as AAHC), and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence (PL) spectra and decay curves. XRD indicated that Cr 3+ doped samples calcined at 1473 K were the most of α-Al 2 O 3 phase. SEM showed that the length and diameter of these Cr 3+ doped alumina microfibers were about 3–9 μm and 300 nm, respectively. PL spectra showed that the Al 2 O 3 :Cr 3+ microfibers presented a broad R band at 696 nm. It is shown that the 0.07 mol% of doping concentration of Cr 3+ ions in α-Al 2 O 3 :Cr 3+ was optimum. According to Dexter's theory, the critical distance between Cr 3+ ions for energy transfer was determined to be 38 A. It is found that the curve followed the single-exponential decay.