Temperature dependent XAFS studies of local atomic structure of the perovskite-type zirconates

Physical review. B, Condensed matter (Impact Factor: 3.77). 01/2006; 73:134109. DOI: 10.1103/PhysRevB.73.134109

ABSTRACT Temperature dependent preedge and extended x-ray absorption fine structure measurements at the Zr K edge for the perovskite-type zirconates PbZr0.515Ti0.485O3 (PZT), PbZrO3 (PZ), and BaZrO3 are performed. To carry out a more accurate study of the weak reconstruction of the local atomic structure we employed a combination of two techniques: (i) analysis of the preedge fine structure, and (ii) analysis of the Fourier transform of the difference between χ(k) functions obtained at different temperatures. A detailed investigation of local atomic structure in the cubic phase for all the crystals is also performed. It is shown that neither the displacive nor the order-disorder model can describe correctly the changes of local atomic structure during phase transitions in PZ and PZT. A spherical model describing the local atomic structure of perovskite-type crystals suffering structural phase transitions is proposed.

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