Relaxor-like dielectric behavior in La2NiMnO6 double perovskite ceramics

The dielectric and conductive characteristics of La2NiMnO6 double perovskite ceramics were investigated together with the crystal structure. La2NiMnO6 ceramics crystallized in the monoclinic P21/n structure in which the Ni2+ and Mn4+ ions ordered periodically. Relaxor-like dielectric behavior combined with a giant dielectric constant step was observed in the present ceramics, and these unique dielectric characteristics should be attributed to the charge ordering of Ni2+ and Mn4+. The dielectric relaxation was well fitted by the modified Debye equation and Arrhenius law with the activation energy of 0.17 eV. The dc conductivity of La2NiMnO6 could be well fitted using a variable-range hopping mechanism instead of a band conduction mechanism.