QUANTITATIVE ENERGY DISPERSIVE-X-RAY ANALYSIS OF BIR-SR-CA-CU-O COMPOUNDS USING STANDARDS

The quantification of energy dispersive X-ray spectra obtained from Bi-Sr-Ca-Cu-O (BSCCO) superconducting materials in scanning and transmission electron microscopes (SEM and TEM, respectively) has been performed using rapidly solidified material as a standard. Quantification based on this amorphous standard material results in significant improvements in accuracy compared to results from semi-quantitative routines. Spectra obtained in the TEM were analyzed using a thin-film approximation and a relative error of less than +/- 3% of the amount present was obtained. Spectra obtained in the SEM required iterative corrections for backscattering, absorption and fluorescence, but since the standard compositions are close to those of the unknown phases and can be prepared for a wide range of compositions, the errors associated with those corrections can be minimized. Measurements performed in the SEM and TEM using these techniques have allowed a correlation between nominal alloy composition and the true composition of the BSCCO superconducting phase to be made. It is found that the presence of intergrowths can have a significant effect on compositions measured by SEM or microprobe techniques.