Electron channeling X-ray microanalysis for site occupation of the additional element in half-Heusler

The site occupancy of Sb atoms in a thermoelectric material TiNiSn_0.9Sb_0.1 with the half-Heusler structure was analyzed by measuring characteristic X-ray intensities at various electron incident directions in a transmission electron microscope (TEM). This technique is called the method for determining atomic locations by channeling enhanced microanalysis (ALCHEMI). The incident electron intensities in half-Heusler structure calculated by dynamical electron diffraction theory were compared with the measured characteristic X-ray intensities. The measured characteristic X-ray intensity for each element changed together with the change of incident electron intensities, depending on the electron incident directions. From the dependence of the X-ray intensities, the distribution fractions of Sb atoms on each site were quantitatively clarified. As a result, the distribution fractions of Sb atoms on Ti, Ni and Sn sites were shown to be -0.07, 0.12 and 0.95, respectively.