A novel approach to achieve high dielectric permittivity and low loss tangent in CaCu3Ti4O12 ceramics by co-doping with Sm3+ and Mg2+ ions

作者：Boonlakhorn Jakkree; Kidkhunthod Pinit; Thongbai Prasit^*

来源：Journal of the European Ceramic Society, 2015, 35(13): 3521-3528.

DOI：10.1016/j.jeurceramsoc.2015.06.008

• Dielectric permittivity
• Impedance spectroscopy
• Loss tangent
• Non-Ohmic properties
• Co-doping

A novel strategy to improve the dielectric properties of CaCu3Ti4O12 ceramics was proposed by codoping with Sm3+ and Mg2+. Sm3+ substituted in Ca2+ sites can effectively suppress the grain growth, achieving a fine grained ceramic microstructure. Mg2+ was selected to be substituted into Cu2+ sites to enhance the grain boundary (GB) resistivity for reducing the loss tangent (tan delta). High dielectric permittivity epsilon' approximate to 1.25 x 10(4) and low tan delta approximate to 0.039 at 1 kHz were successfully accomplished in a Ca0.925Sm0.05Cu2.70Mg0.30Ti4O12 ceramic. Non-Ohmic properties were also enhanced. A slight increase in Ti3+/Ti4+ ratio in (Sm+ Mg) co-doped CaCu3Ti4O12 ceramics was confirmed by the X-ray absorption near edge structure. Changes in tan delta values for all the co-doped ceramics were very consistent with their variations in GB resistance. The dielectric and non-Ohmic properties of co-doped ceramics were significantly improved by tuning both the geometric and intrinsic factors, i.e., increasing the density of GB layer and enhancing the GB resistance, respectively.

• 出版日期2015-11