Extremely reduced loss tangent with retaining ultra high dielectric permittivity in Mg2+-doped La1.9Sr0.1NiO4 ceramics

Keerati Meeporn; Narong Chanlek; Pornjuk Srepusharawoot; Prasit Thongbai

doi:10.1016/j.heliyon.2023.e13583

Extremely reduced loss tangent with retaining ultra high dielectric permittivity in Mg²⁺-doped La_1.9Sr_0.1NiO₄ ceramics

Heliyon. 2023 Feb 9;9(2):e13583. doi: 10.1016/j.heliyon.2023.e13583. eCollection 2023 Feb.

Authors

Keerati Meeporn¹, Narong Chanlek², Pornjuk Srepusharawoot³, Prasit Thongbai³

Affiliations

¹ Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand.
² Synchrotron Light Research Institute (Public Organization), 111 University Avenue, Muang District, Nakhon Ratchasima 30000, Thailand.
³ Giant Dielectric and Computational Design Research Group (GD-CDR), Department of Physics, Institute of Nanomaterials Research and Innovation for Energy (IN-RIE), Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand.

Abstract

An extremely reduced loss tangent while retaining ultrahigh dielectric permittivity can be successfully obtained in La_1.9Sr_0.1NiO₄ ceramics by doping with Mg²⁺ ions. A single phase of La_1.9Sr_0.1NiO₄ was detected in all the sintered ceramics, while the lattice parameters increased with increasing doping concentration, indicating that Mg²⁺ ions can enter the Ni²⁺ sites. A highly dense microstructure is achieved. Microstructural analysis revealed that Mg²⁺ ions disperse well in the microstructure of La_1.9Sr_0.1NiO₄ ceramics. Interestingly, ultra-high dielectric permittivity of approximately 8.11 × 10⁵ at 1 kHz is achieved in the La_1.9Sr_0.1Ni_0.6Mg_0.4O₄ ceramic, while the loss tangent is significantly reduced by two orders of magnitude compared to the undoped La_1.9Sr_0.1NiO₄ ceramic. The DC conductivity significantly decreased by three orders of magnitude. The giant dielectric responses are described by Maxwell-Wagner polarization and small polaron hopping mechanisms. Thus, the significant reduction in the loss tangent can be attributed to the significantly enhanced resistance of the grain boundaries.

Keywords: DC conduction; Giant dielectric properties; Loss tangent; Maxwell−Wagner polarization; Nickelate.