Effects of Ga Substitution for Cu on Microstructure and Giant Dielectric Response of CaGa_xCu_3−xTi₄O₁₂(x = 0, 0.01, and 0.05) Ceramics

Abstract

The microstructural changes and dielectric properties of CaGa _x Cu_3-x Ti₄O₁₂(x = 0, 0.01, and 0.05) ceramics were investigated. The mean grain size and dielectric constant of CaGa_0.01Cu_2.99Ti₄O₁₂ceramic increased by roughly a factor of 40, but decreased by roughly a factor of 100 with increasing levels of Ga³⁺ doping corresponding to the CaGa_0.05Cu_2.95Ti₄O₁₂ceramic. The resistance of grain boundaries of CaGa_0.01Cu_2.99Ti₄O₁₂ceramic decreased significantly. As levels of Ga³⁺ doping increased (x = 0.05), the resistance of grain boundaries was enhanced greatly. The giant dielectric response in CaGa _x Cu_3-x Ti₄O₁₂ceramics can be well described based on their electrically heterogeneous microstructure and was found to be correlated with their microstructure.

Keywords:

• Grain boundaries
• dielectric properties
• electrical properties
• impedance spectroscopy, dielectric relaxation

Acknowledgments

This work was supported by the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission, through the Advanced Functional Materials Cluster of Khon Kaen University and the Integrated Nanotechnology Research Center (INRC), Khon Kaen University, Thailand. J.J. extends his gratitude to the Thailand Graduate Institute of Science and Technology (TGIST) for his Master of Science Degree scholarship.