Microanalysis of bismuth indium selenide thermoelectronic materials by X-ray fluorescence spectrometry with reference assays of indium
Abstract
Screening of a small area on the natural cleavage face of a layered single crystal was used for X-ray fluorescence spectrometric (XRF) assays. A precise determination of indium (within the range 1–8% m/m) in Bi2–xInxSe3 single crystals was based on the calibration of the net intensity of the In Kα1,2 line with the use of the results of extraction–photometric analysis after decomposition of the crystal chips exposed to X-rays. In acetate buffer medium (pH ≈ 4.0, Vaq= 40 cm3) and with an adequate excess of quinolin-8-ol and thiosulfate (masking of bismuth), the tris(quinolin-8-olato)indium(III) chelate was completely transferred into 10 cm3 of chloroform. The absorbance of the chloroform extract was measured at 400 nm against a blank extract. For calibration of the X-ray spectrometer a computer program was written using a simplified least-squares method of linear regression for both variables subject to experimental error. The XRF method allows the selection of a piece of crystal suitable for measurements of physical parameters.