Measurements of emission spectra and decay times of Eu3+, Sm3+ Tb3+, Dy3+ and Gd3+ and their concentration dependence were taken in silicate glasses, in the concentration range 0.05–1.00 weight percent, under monochromatic excitation. The results are compared with those obtained in borate glasses. The lower intensities of the main emission lines for all the five R. E., the longer decay times for Tb3+ and Sm3+ and the shift to shorter wavelengths for Eu3+ and Sm3+ are explained in terms of the lower field strength seen by the R. E. in silicate glasses and smaller energy transfer probabilities.
A8STRACTThe diffusion of europium was studied in single crystals of potassium chloride by the spectrophotometric method. Measurements were carried out in the temperature range 418-550·C. The absorption spectra as welJ as the fluorescence spectra of crystals showed that europium diffused in its divalent state, being reduced by the crystal field of potassium chloride. The diffusion of europium can be represented by the equation D = 6.45' 10-zexp(-29,400/RT). It is concluded that the activation energy consists of the sum of the jump energy of EUZ+ and of the enthalpy of solution of EUCIz in KC!.
A novel attachment to the Beckman DU spectrophotometer is described, by means of which the diffusion profile of some heavy-metal ions in alkali halides may be recorded.
The diffusion of Tl+ ions in KCl in the temperature range 270°-400°C was measured. It is concluded that the activation energy for the diffusion of Tl+ varies with temperature, parallel to that of the self-diffusion of K+ ions, calculated from conductivity measurements. The diffusion constants of the Tl+, at any temperature, are several orders higher, as the associated vacancies of the divalent impurities present are also involved in the diffusion process.
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