title: Luminescence properties of Sm(3+)-doped P(2)O(5)-PbO-Nb(2)O(5) glass under high pressure.
abstract: Samarium doped lead phosphate glass modified with niobium having a composition (in mol%) of 55P(2)O(5)+39.5PbO+5Nb(2)O(5)+0.5Sm(2)O(3) has been prepared by the conventional melt quenching technique. The emission spectra and the decay curves for the (4)G(5/2) level of Sm(3+) ions have been measured as a function of pressure up to 23.6 GPa at room temperature. A discontinuity in the observed shifts and crystal-field splittings as a function of pressure around 9-10 GPa suggests that a phase transition is taking place in the glass matrix. The [Formula: see text], (6)H(7/2) and (6)H(9/2) transitions are shifted towards the lower energy side with magnitudes of -7.1, -7.6 and -5.5 cm(-1) GPa(-1) up to 8.9 GPa (phase 1) and -5.6, -4.9 and -4.4 cm(-1) GPa(-1) beyond 10.3 GPa (phase 2), respectively. A much stronger increase in the splitting of the [Formula: see text] and [Formula: see text] Stark levels with pressure is observed in phase 1 than in phase 2. The lifetime of the (4)G(5/2) level decreases from 2.29 ms (0 GPa) to 0.64 ms (23.6 GPa) with pressure. The decay curves of the (4)G(5/2) level exhibit non-exponential behavior for all the pressures and were fitted by the generalized Yokota-Tanimoto model to probe the nature of the energy transfer process. The best fits with S = 6 indicate that the energy transfer between donor and acceptor is of dipole-dipole type. The crystal-field splitting experienced by the Sm(3+) ions in the title glass are found to be larger than those found in borate, K-Ba-Al phosphate and tellurite glasses.
authors.affiliation: Department of Physics, Sri Venkateswara University, Tirupati-517 502, India.
authors.forename: R
authors.initials: R
authors.lastname: Praveena
authors.forename: V
authors.initials: V
authors.lastname: Venkatramu
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