Inorganica Chimica Acta, 150 (1988) 141-146 141 Absorption and Luminescence Spectroscopy of Eu3+ in Lead Silicate Glasses zyxwvutsrqponmlkjihg FERNANDO FERMI, LAURA TELLINI Dipartimento di Fisica, Universitd di Parma, Viale delle Scienze, 43100 Parma, Italy GIANLUIGI INGLETTO* Istituto di Biochimica, Facolta di Medicina Veterinarh, Universitd di Parma, Via de1 Taglio, 43100 Parma, Italy ANNA VINATTIERI Dipartimento di Fisica, Universitd di Firenze, Largo E. Fermi 2, 50125 Florence, Italy and MARCO BETTINELLI Dipartimento di Chimica Inorganica, Metallorganica ed Analitica, Universitd di Padova, Via Loredan 4, 35131 Padua, Italy (Received March 30, 1988) Abstract The absorption and luminescence spectra of a lead silicate glass containing Eu3+ as impurity have been measured. The doping ion was found to occupy two classes of non-centrosymmetric sites. The intensities of the 4f6 + 4f6 transitions are perturbed by the interaction with low-lying charge-transfer states. The quantum yield of the luminescence from the ‘De level of Eu3+ is unusually low, probably because of the presence of a strong ion-phonon coupling. Introduction It is well known that rare-earth doped glasses are of interest for laser technology [I], particularly because they are available at a low cost and are easily prepared, with respect to single crystals. So, a study of the luminescence process and of the radi- ative and non-radiative decay of the impurity levels is necessary to evaluate some fundamental data, such as the radiative lifetime and the luminescence quantum yield of the excited states. In fact, these parameters are important in order to estimate the threshold power for the laser excitation [2]. On the other hand, as far as the theoretical aspects are concerned, several authors have used the Eu3+ ion as a probe to understand the symmetry of the sites in which a rare-earth ion can be embedded in a glass [3-S]. For these reasons we investigated from this point of view the glass system PbO/SiOa with this kind of probe, bearing in mind that the structure of the lead silicate glasses is not completely under- stood [6]. *Author to whom correspondence should be addressed. 0020-I 693/88/$3 SO The choice of this kind of host matrix is also due to the fact that it contains a high concentration of the polarizable Pb*+ . ion. Its presence could influence the nature of the chemical bond between the rare- earth ion and its surroundings and so could affect the radiative transition probabilities and the intensity of the bands if compared with glasses containing other modifier cations [7-91. Moreover, a high concentration of the Pb*+ ion in the random network of the glass could modify the ion-phonon coupling. In this contribution we report the absorption and luminescence spectra of Eu3* in a lead silicate glass and determine its radiative transition probabilities and the lifetime of the ‘De excited level. The former are discussed in the framework of the Judd-Ofelt parametrization scheme. Experimental The molar composition of the lead silicate glass under investigation was 37.5% PbO, 61.5% SiOZ and 1% Eu203. Several batches were prepared by mixing appropriate quantities of SiOZ, PbO (both Carlo Erba RPE) and Euz03 (Riedel-De Haen reagent grade) in a platinum crucible and melting them at 1200 “C for 2 h in an electrically heated muffle furnace. The samples were quenched onto a stainless steel plate and annealed at 3.50 “C for 6 h. They were then cut and polished for the optical measure- ments. Absorption spectra in the near infrared, visible and ultraviolet regions were measured using a Cary 17 spectrophotometer. The samples were held at 293 K and 80 K in a simple laboratory-built cryostat. The 80 K absorption spectrum was recorded only in the visible region. An undoped 38% PbO-62% SiOZ glass of the same thickness was used as reference 0 Elsevier Sequoia/Printed in Switzerland