EXAFS study of Zr environment in amorphous precursors of $Pb(Zr,Ti)O_3$

Homogeneity of the amorphous sol-gel precursors of Pb(Zr,Ti)O3 ferroelectric ceramics is studied at various Zrfri ratios. From Zr K-edge EXAFS spectra the immediate vicinity of Zr atoms is determined. A distorted octahedron of O atoms with all the bonds continued in Zr-O-Zr links is observed down to Zrfri ratio of 1:1, indicating the prevalent homocondensation of Zr. In the precursor with Zr/Ti ratio of 25/75 a smaller distortion of O octahedra is observed and heterometallic bonding Zr-O-Ti is found. Mixing of the two metals (Zr, Ti) at molecular level is thus established at low Zr/Ti ratios