title: Photoluminescence from the (5)D(0) level of Eu(3+) ions in a phosphate glass under pressure.
abstract: The pressure dependence of the luminescence from [Formula: see text] transitions of Eu(3+) ions in 58.5P(2)O(5)-9Al(2)O(3)-14.5BaO-17K(2)O-1Eu(2)O(3) glass has been investigated up to 38.3 GPa at room temperature. The relative luminescence intensity ratio of [Formula: see text] to [Formula: see text] transitions of the Eu(3+) ions is found to decrease with increasing pressure, indicating a lowering of the asymmetry around the Eu(3+) ions with pressure. The [Formula: see text] transitions exhibit pressure-induced red shifts of different magnitude, which suggests a decrease in Slater parameters (F(k)) and in the spin-orbit coupling parameters (ζ) for the Eu(3+) ions. Stark components of the (7)F(1) level have been used to evaluate the crystal-field (CF) parameters B(20) and B(22), which are in turn used to estimate the CF strength experienced by the Eu(3+) ions in the glass. The observed increase in the CF strength parameter is found to have an almost cubic dependence on pressure. Luminescence decay curves for the [Formula: see text] transition are found to be single exponential over the entire pressure range studied. The lifetime did not change under pressure up to 5 GPa, although a significant change in the CF strength is noticed in this pressure range. The reduction of lifetime observed at pressures above 5 GPa could be partially due to an increase of pressure-induced defect centres. Such a process can then explain the hysteresis observed in the variation of lifetime and crystal-field strength on the release of pressure.
authors.affiliation: Department of Physics, Sri Venkateswara University, Tirupati-517 502, India.
authors.forename: S
authors.initials: S
authors.lastname: Surendra Babu
authors.forename: P
authors.initials: P
authors.lastname: Babu
authors.forename: C K
authors.initials: CK
authors.lastname: Jayasankar
authors.forename: Th
authors.initials: T
authors.lastname: Tröster
authors.forename: W
authors.initials: W
authors.lastname: Sievers
authors.forename: G
authors.initials: G
authors.lastname: Wortmann