The temperature dependence for the third shell's Fourier-peak of Nb-EXAFS in KNbO3 as additional source of information on the local atomic structure

The information on the structure of tetragonal KNbO3 is extracted from the temperature dependence of the third shell's Fourier-peak of Nb-EXAFS. It is shown that this dependence can be explained by two effects: 1) rigid rotat ions of the O-6-octahedron and 2) increase of the third shell's DW-paramete r. However, diffraction data on the temperature dependence of the DW-parame ter permit us to conclude that the last effect only is sufficient and the O -6-octahedron rotation doesn't occur in the high-temperature phases of KNbO 3. Using EXAFS it is revealed that in the neighboring cells Nb-atoms are pa rallel shifted closely to [211] direction in tetragonal phase.