Charge order, dielectric response, and local structure of La5/3Sr1/3NiO4 system

Charge ordering, dielectric permittivity, and local structure of La5/3Sr1/3NiO4 system have been explored by x-ray charge scattering, complex dielectric impedance spectroscopy, and extended x-ray absorption fine structure (EXAFS) measurements, made on the same single crystal sample. The local structure measured by the temperature-dependent, polarized Ni K-edge EXAFS shows significant distortions in the NiO2 planes. These local distortions could be reasonable cause of high dielectric permittivity of the title system (epsilon approximate to 100 at 5 K) with the charge ordering in this system being a ferroelectriclike second order transition. (C) 2009 American Institute of Physics. [doi:10.1063/1.3260222]