Optical characterization of spherical fine particles of glassy Eu 3+ doped yttrium basic carbonates

Abstract

Spherical fine particles of glassy Eu 3+ doped yttrium basic carbonate, whose sizes are about 300 nm in diameter, are prepared by a co-precipitation method using urea as a precipitation generator. The optical properties concerned with the f–f transitions of Eu 3+ are investigated for the as-prepared powder and the powder samples calcined at 300 and 550 °C. As the calcination temperature becomes high, the absorption band (charge-transfer band) due to the electron transfer from O 2− to Eu 3+ shifts to lower energy. The forced electric dipole 5 D 0– 7 F J ( J=0,2,3,4) transition strengths and the inhomogeneous width of the 5D 0– 7F 0 luminescence spectrum of Eu 3+ increase with calcination temperature. From these results, the local structure around Eu 3+ is compared among the three powder samples. The persistent spectral hole burning (PSHB) effect is observed at 10, 70, and 120 K in the 7F 0– 5D 0 transition of Eu 3+ in all the samples. It is found that, at these temperatures, the burning reaction rate decreases with increasing calcination temperature. Probable PSHB mechanisms of the three samples are discussed.