LaFe_(1-x)Cr_xO_3系列氧化物的EXAFS研究

Study on Perovskite Oxides LaFe_(1-x)Cr_xO_3 by EXAFS

采用固相反应法,制备了钙钛矿结构氧化物LaFe_(1-x)Cr_xO_3较宽范围内(x=0．0—0．7)的系列单相样品,并测量了各样品的X射线衍射谱(XRD)和扩展X射线吸收精细结构(EXAFS)谱．通过对XRD的分析样品均为钙钛矿结构正交相,同时晶格常数随着掺杂量x的增加而减小．通过对EXAFS的分析和研究得到在LaFe_(1-x)Cr_xO_3氧化物中Fe-O键长和Fe-La键长随掺杂浓度x的变化,发现Fe-La键长发生比较大的变化,说明La在体系掺杂中对结构的稳定起到重要作用．

Perovskite oxides LaFe1-xCrxO3 were synthesized by solid state reaction method. X-ray powder diffraction was tested to characterize the crystalline structure of the samples. The result indicates that the samples are single orthorhombic phase. The lattice parameter decreases with the Chromium concentration. The extend X-ray absorption fine structures （EXAFS） of the Fe K-edge as a function of doping level x show that the Fe-La bonds distance decreases dramatically. This suggests that Lanthanum is very important for the stability of the whole LaFe1-xCrxO3 structure.