Optical Transitions near the Fundamental Absorption Edge and Electronic Structures of YAl3(BO3)4:Gd3+

概要

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Optical properties of Gd3+ ions doped in YAl3(BO3)4 are investigated as a new UV phosphor under excitation of VUV radiation. A strong emission line at 3.96 eV (313 nm) corresponding to the transitions from the $^{6}P_{7/2}$ to $^{8}S_{7/2}$ states of Gd3+ ions is observed. We performed the Rietveld refinement using an X-ray diffraction result to obtain the structural parameters of a synthesized YAl3(BO3)4:Gd3+ phosphor. From the result, it is shown that the refined crystal structure of YAl3(BO3)4:Gd3+ phosphors is slightly distorted. The electronic structures have been calculated using the relativistic discrete variational X$\alpha$ method. The calculations indicate that the optical properties of a non-doped YAl3(BO3)4 crystal near the fundamental absorption edge are characterized by the electronic transitions from O $2 p$ valence states to B $2 p$ conduction states. On the other hand, it is found that the origin of the absorption edge of YAl3(BO3)4:Gd3+ phosphor is due to the transitions from O $2 p$ states to mixed states of mainly B $2 p$ and Y $4d$ orbitals.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2006-01-15