摘要

Large Li2BaAl2F10 single crystals of optical quality were grown using the vertical Bridgman method. X-ray diffraction method was used to determine the crystal structure (orthorhombic symmetry Cmc2(1)), lattice parameters, atomic coordinates. The luminescent properties were investigated using selective photo excitation by synchrotron radiation (E = 3.7-21 eV, T = 8 K, time integrated and time-resolved spectra) as well as upon excitation with unfiltered X-ray beam (synchrotron radiation or X-ray tube). We revealed both the broadband luminescence at E (m) = 4.0 eV (E (ex)=11.72 eV) attributed to the radiative annihilation of self-trapped excitons (STE) and the excitonic-type near-defect luminescence at E (m) = 3.0-3.2 eV (E (ex)=11.25 eV) attributed to radiative relaxation of electronic excitations in nonequivalent structural units of the crystal lattice. The fast exponential component with lifetime of 5.6 ns, a low-intensity intermediate component with a lifetime of 75-100 ns, a constant level - pedestal (sum of the micro- and millisecond decay components) were revealed in luminescence decay kinetics. The electronic structure parameters (bandgap E (g) = 13.0 eV, low-energy onset of the intrinsic host absorption E (c) = 11.2 eV), the energy threshold for the excitation of STE-luminescence (E t(h) = 11.2 eV) are determined from spectroscopic data. Thermoluminescence cm has been studied (90-350 K) using spectral-integral regime. Four partially overlapping TL glow peaks were revealed, their deconvolution was done and thermal activation parameters were determined using TGCD method.

  • 出版日期2018-2

全文