Simultaneous ICP atomic emission spectrometry for accurate stoichiometric determination: application to a YNi2B2C superconducting material system

Abstract

For characterisation of the exact stoichiometry of semiconductor or superconductor compounds, the determination of major components with high precision and accuracy is necessary. In order to assess ICP-AES for this task, sophisticated procedures for sample preparation, measurement optimisation and data correction and evaluation, such as multi-line measurements for each analyte element, optimum calibration and recalibration, and internal standardisation, have been developed for simultaneous Echelle spectrometers with CID or CCD detectors. Procedures and results are demonstrated for superconducting materials of the YNi2B2C type. For the analyte elements Y, Ni and B, as well as for the internal standard element In, three optimum spectral lines were used. Calibration and external standardisation were carried out using different mixtures of mono-elemental standard solutions. The confidence intervals for the determination of Y, Ni and B were lowered to 0.17, 0.11 and 0.13% (w/w), respectively. Thus, the stoichiometric coefficients were determined with an error smaller than 0.002, 0.002 and 0.003 for Y, Ni and B, respectively. Using the F-test, the sample homogeneity was tested and, in this way, the presence of trace amounts of secondary phases were detected.