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Luminescence centers in lead silicate glasses

1968; Elsevier BV; Volume: 1; Issue: 1 Linguagem: Inglês

10.1016/0022-3093(68)90008-2

1873-4812

C. Bettinali, G. Ferraresso,

Photorefractive and Nonlinear Optics

Absorption spectra and luminescence spectra of lead silicate glasses excited by the 2537 Å Hg line have been studied at liquid nitrogen temperature. The samples studied were three lead glasses of the system K2OPbOSiO2 having a PbO content of 1.5, 13.5 and 28.5 mol%, PbCl2 and BaCl2(Pb). The glassy samples having 1.5 and 13.5 PbO mol% show three emission maxima at about 2.7, 3.4 and 3.9 eV respectively; BaCl2(Pb) at 2.78 3.50 and 3.94eV. PbCl2 and the glass containing 28.5 mol% of PbO show a single luminescence maximum at 2.78 and 2.54 eV respectively. The relative efficiency (η) and the activation energy of thermal quenching (Es) have been measured. The Stokes shift (Δε) has been evaluated from emission and absorption data. The relation between, η, Es and Δε is discussed. Experimental results suggest that: a) Emission of lead silicate glasses is not related to Pb0 atoms but to Pb++ ion levels; b) The visible emission, both in vitreous and in crystalline compounds, is related to the 3P0→1S0 transition; c) The thermal dependence curves of luminescence efficiency agree with a localized center both in glass and in crystals; d) The Stokes shift, activation energy of thermal quenching and the luminous efficiency can be related by means of multiphonon theory. The results confirm the similarity of emitting centers in glasses and in crystals.