Tilting of the CuO6 octahedra in La1.83-xEu0.17SrxCuO4 as seen by Eu-151 Mossbauer spectroscopy

Eu-151 Mossbauer studies of La1.83-xEu0.17SrxCuO4 for 0 less than or equal to x less than or equal to 0.26 exhibit a quadrupole interaction at the Eu site whose magnitude eQV(zz) strongly depends on both the Sr content x and the temperature T. For a fixed temperature, a Linear relationship is obtained between the quadrupole interaction and the averaged CuO6 octahedra tilting angle determined from diffraction studies. The unusually large temperature dependence of eQV(zz) strongly indicates a temperature dependence of the local structure. In contrast to recent studies of the local structure La2CuO4-type superconductors by means of x-ray-absorption and neutron-scattering techniques, our data give strong evidence that the local octahedra tilting in La1.83-xEu0.17SrxCuO4 corresponds well to the average tilting obtained by diffraction techniques.