科研之友
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摘要
Here, we describe the analysis of the nanostructure and average chemical compositions of each phase present in an oxyfluoride glass ceramic, which is composed of fluoride nanocrystals and an oxide glass matrix. The overall composition of the oxyfluoride glass ceramic as prepared is 21.1%SiO2 6.5%B2O3 7.0%Al2O3 21.0%PbF2 14.3%CdF2 11.0%YbF3 0.5%ErF3 11.0%PbO 7.6%CdO (mole %). Nanocrystals begin to grow at temperatures above the glass transformation temperature at 678 K as observed by x-ray diffraction. We report results from anomalous small-angle x-ray scattering taken at energies of x-ray absorption edges of Er, Yb, Pb, and Cd. By nonlinear regression of the scattering curves obtained from different edges simultaneously, the nanocrystals were found to be describable as polydisperse spheroids. The length of the smaller axis was found to be 6.4 + 1.4 nm while the larger axis was found to be 17.7 + 3.9 nm. By analyzing the scattering contrast as a function of the x-ray energy we found cadmium only in the glass matrix.
- 出版日期2010-5-1
