Excitation mechanisms of green emiss ion from terbiu m ions embedded inside th e sol-gel films deposited onto nano-porous substrates

摘要

In this work we investigate the excitation mechanism of Tb~(3+) ions in different inorganic sol-gel matrices (composite film of YAIO3 and Al_2O_3; Ba_(0.6)Sr_(0.3)Ca_(0.1)TiO_3) in porous anodic alumina films. The interest in synthesis of light-emitting materials in porous anodic alumina arises from its unique tailor-made honey-comb structure, strongly enhanced Tb luminescence and great photonic density of states at direction along the channels of the anisotropic light scattering. All discussed sol-gel films were synthesized by spin-on deposition on porous anodic alumina grown on a silicon wafer and annealed at different temperatures. An influence of the annealing temperature on the terbium PL was studied using XRD, 2D photoluminescence excitation and time-resolved spectroscopy. Further, the comparison of thermal quenching data for the most intensive ~5D_4→~7F_5 luminescence band and excitation band of Tb ~(3+) ions was performed for the temperature range of 10 - 300 K. From the resultant data, mechanisms of Tb excitation and its dependence on the annealing conditions are proposed and discussed.