Investigation of phase and dielectric properties of lead nickel tantalate ceramics

ABSTRACT

Lead nickel tantalate (PNT) ceramic was prepared by solid-state reaction method using 2-step columbite precursor route. Phase analysis of samples sintered at 1473 K shows PNT pyrochlore phase with minute peaks of NiO rich phase. 2-phase Rietveld refinement of x-ray diffraction patterns reveal ∼92.4 (0.33) % pyrochlore phase (cubic structure; space group: Fd-3m; a = 10.5867(4) Å). From temperature dependent dielectric constant and dissipation factor study, strong frequency dependent dielectric anomaly within 140–240 K, related to relaxation rather than structural changes in PNT ceramic is obtained. Observed Arrhenius behavior of dielectric relaxation is believed to be associated with single-ionized oxygen defect hopping.

KEYWORDS:

• Lead nickel tantalite
• pyrochlore
• Rietveld refinement
• dielectric relaxation
• single-ionized oxygen defects

Acknowledgments

Authors are grateful to Dr. Archna Sagdeo for XRD measurement, Prof. A. K. Nigam for FE-SEM measurement, Devendra Buddhikot for the help during FE-SEM measurements and Ashok Bhakar for dielectric measurement. Mr. Pandey acknowledges Homi Bhabha National Institute, RRCAT, Indore for the research fellowship.