Crystal structure, dielectric relaxation and magnetic properties of Ba5NdNiNb9O30 ceramics

In this paper, we report on the preparation, dielectric and magnetic properties of Ba5NdNiNb9O30 ceramics and its structural refinement. Ba5NdNiNb9O30 powders were synthesized by solid state reaction at 1350 °C for 3 h. X-ray diffraction and Rietveld refinement analysis revealed that the ceramics present a single phase with tetragonal tungsten bronze structure in space group P4bm. Broad dielectric peaks with strong frequency dispersion were observed in the temperature range from 150 to 230 K. The frequency dependence of the dielectric maximum temperature well follows the Vogel–Fulcher relationship and the relaxor behavior can be well fitted with the modified Curie–Weiss law with a diffusivity parameter value of 1.69 at 1 kHz. The temperature dependence of magnetization suggests the absence of a long-range magnetic ordering while a negative paramagnetic temperature θWeiss indicates the presence of weak antiferromagnetic interactions.

► Ba5NdNiNb9O30 ceramics with tetragonal tungsten bronze structure were synthesized.
► Magnetic Ba5NdNiNb9O30 is a relaxor.
► Off-centering of Ni/Nb at B sites contributes to ferroelectricity of Ba5NdNiNb9O30.
► Random distributions of ions at A and B sites result in dielectric relaxation.