Structure analysis of cation selective Cr-goethite as protective rust of weathering steel

Konishi, Hiroyuki; Yamashita, Masato*; Uchida, Hitoshi*; Mizuki, Junichiro

We have performed extended X-ray absorption fine structure (EXAFS) analysis for artificial Cr-goethite to elucidate the local structure around Cr in Cr-goethite. The spectra were obtained using synchrotron radiation X-rays at the Photon Factory in Tsukuba. The first shell contributions were isolated by Fourier filtering the EXAFS data, and the inverse Fourier transformed single-shell data were analyzed using curve fitting method. The results show that Cr is coordinated with (71) O ions. The protective character of Cr-goethite protective rust layer on weathering steel can be interpreted in terms of the O coordination around Cr resulting in creation of negative fixed-charge in the Cr-goethite particles.