Studies on the quantitative analysis of trace elements in single SiC crystals using laser ablation-ICP-MS

Abstract

A technique has been developed for the simultaneous determination of the trace elements Al, Cu, Mn, V, Ti and Fe in single SiC crystals by laser ablation-ICP-MS. The wavelength of 1064 nm of an Nd∶YAG laser operating in the ‘free-running’ mode is used for ablation, because in the Q-switched mode the signal-to-noise ratio was too low to obtain the analytical reproducibility required. Sample preparation is simple, as only purification of the crystal surface with HF is necessary. To prepare calibration standards, multi-element solutions were added to pure SiC powder. The powder was dried, homogenized and pressed to pellets using carbon powder as binding material. The verification of the calibration was carried out with powdered SiC reference materials. Acceptable recovery rates of between 95 and 110% were obtained. The limits of detection were between 3 × 10–9 g g–1 (V) and 4 × 10–8 g g–1 (Cu). Relative standard deviations measured at trace element concentrations of about 1 × 10–6 g g–1 were less than 10% when the intensities of 10 craters each with 500 laser shots were averaged.