Structural and dielectric characterization of triple perovskites Ba3NiTaNbO9 and Ba3NiTaSbO9

The perovskites barium nickel tantalum niobium oxide (BNTN) and barium nickel tantalum antimony oxide (BNTS) consisting of two rare earth elements have been prepared by the ceramic method. The BNTN sample crystallizes in trigonal symmetry with P-3m1 space group and the BNTS sample crystallizes in hexagonal symmetry with P 6(3)/mmc space group, which has been obtained from the analysis of the powder x-ray diffraction pattern (XRD). The results of the structural analysis match well with that of the Raman and Fourier transform infrared spectroscopic studies. For both the samples the dielectric relaxation and ac conductivity were investigated in between temperatures 333 K-573 K and in between 10 Hz and 1 MHz frequency. The relaxation nature of the samples has been analyzed with the help of the Cole-Cole model. The non-zero values of alpha for the Cole-Cole model suggests the relaxation phenomena being polydispersive in nature. The activation energy as obtained from the conductivity spectra is 0.36 eV for BNTN and 0.37 eV for BNTS which indicates that the polaron hopping mechanism is responsible for their electrical and dielectric response. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Perovskites BNTN and BNTS, consisting of two rare earth elements and prepared by the ceramic method, crystallize in different space groups and show good agreement between structural analysis and spectroscopic studies. Dielectric and AC conductivity properties were studied at different temperatures and frequencies, revealing a polydispersive relaxation phenomenon and indicating the influence of polaron hopping mechanism on their electrical and dielectric response.