Structure Correlated Enhancement in Dielectric and Electrical Properties of Strontium Based Niobates

Abstract

Structural, dielectric and transport properties of single phase Sr(B′_1/3Nb_2/3)O₃ where (B′ = Mg²⁺, Co²⁺, Cu²⁺) relaxor ferroelectric compounds synthesized by standard solid state reaction technique, are reported here. All the samples exhibit strong correlation between structure, dielectric and transport behavior. In this system significant Jahn-Teller distortion, induces enhancement in dielectric properties. Further, weak Jahn-Teller distortion due to unevenly occupied t_2g levels in Co²⁺ produces intermediate rise in ϵ′ as well as inbuilt flexibility to conduction electron movement enhances dielectric loss (tanδ). On the other hand, strong Jahn-Teller effects in Cu²⁺ substituted compound, due to unevenly occupied e_g levels, results in large enhancement in ϵ′ and frequency exponent ‘s’. This is accompanied by significant fall in dielectric loss due to localization of conduction electrons within oxygen octahedron.

Keywords:

• X-ray diffraction
• dielectric properties
• SEM
• Ferroelectric
• Conductivity
• 1:2 Niobates

Acknowledgments

One of the authors B. Bishnoi is very much thankful to the Inter University Accelerator centre (IUAC) New Delhi for providing financial support under the project UFUP-41315 and providing irradiation as well as measurement facility. We are also thankful to UGC DRS Programme for funding experimental facilities in the department.