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Radiative transition probabilities from 3P0, 1I6, 1D2, and 1G4 levels of Tm3+ in glasses were calculated using the matrix elements obtained by intermediate coupling scheme and experimentally obtained intensity parameters. In the absence of self-absorption of fluorescence by the glass host, the fluorescence intensities of Tm3+ and Er3+ increase in the order borate < phosphate < germanate < tellurite. Nonradiative transition probabilities in different glass hosts from 1D2 to 1G4 levels of Tm3+ and from 4S3/2 to 4F9/2 and from 4F9/2 to 4I9/2 levels of Er3+ were calculated. The nonradiative transition rates follow the formula WNR = W (0) exp(−αp), where p is the number of phonons matching the energy gap. The nonradiative transition rates of Er3+ exhibit temperature dependence consistent with the multiphonon relaxation theory. In Tm3+ the temperature dependence of nonradiative relaxation rates is complicated by the existence of self-absorption and transfer of energy from matrix to Tm3+. Based on the above results, quantum efficiencies of luminescence of rare earth in glasses can be predicted.

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SynopsisAn experimental study of the tensile properties, tear strength, hysteresis, and swelling ratio of model composite elastomeric compounds consisting of polybutadiene filled with glass beads has been carried out as a function of the size of the beads. The diameter of the beads ranged from 25 to lo00 jtm and the volume fractions examined were 0.16,0.092, and 0.048. Mechanical properties of the fied elastomers were functions of the loading (separation distance), the particle size (surface aredvolume), and the elastomer-filler systems studied.