[1] X. Zhao, L. Ren, L. Yang, S. Li, R. Liao, W. Li, J. Li. Structure and dielectric relaxations of CaCu3Ti4O12 ceramics by heat treatments in different atmospheres. IEEE Trans. Dielectr. Electr. Insul., 24, 764(2017).

[2] P. Mao, J. Wang, S. Liu, L. Zhang, Y. Zhao, K. Wu, Z. Wang, J. Li. Improved dielectric and nonlinear properties of CaCu3Ti4O12 ceramics with Cu-rich phase at grain boundary layers. Ceram. Int., 45, 15082(2019).

[3] L. Liu, S. Ren, J. Liu, F. Han, J. Zhang, B. Peng, D. Wang, A. A. Bokov, Z. G. Ye. Localized polarons and conductive charge carriers: Understanding CaCu3Ti4O12 over a broad temperature range. Phys. Rev. B, 99, 094110(2019).

[4] J. Boonlakhorn, P. Kidkhunthod, N. Chanlek, P. Thongbai. (Al3+, Nb5+) co–doped CaCu3Ti4O12: An extended approach for acceptor–donor heteroatomic substitutions to achieve high–performance giant–dielectric permittivity. J. Eur. Ceram. Soc., 38, 137(2018).

[5] J. Jumpatam, W. Somphan, J. Boonlakhorn, B. Putasaeng, P. Kidkhunthod, P. Thongbai, S. Maensiri, X. M. Chen. Non-Ohmic properties and electrical responses of grains and grain boundaries of Na1∕2Y1∕2Cu3Ti4O12 ceramics. J. Am. Ceram. Soc., 100, 157(2016).

[6] W. Hu, Y. Liu, R. L. Withers, T. J. Frankcombe, L. Norén, A. Snashall, M. Kitchin, P. Smith, B. Gong, H. Chen, J. Schiemer, F. Brink, J. Wong-Leung. Electron-pinned defect-dipoles for high-performance colossal permittivity materials. Nat. Mater., 12, 821(2013).

[7] Z. Peng, P. Liang, X. Wang, H. Peng, X. Chen, Z. Yang, X. Chao. Fabrication and characterization of CdCu3Ti4O12 ceramics with colossal permittivity and low dielectric loss. Mater. Lett., 210, 301(2018).

[8] S. Guillemet-Fritsch, Z. Valdez-Nava, C. Tenailleau, T. Lebey, B. Durand, J. Y. Chane-Ching. Colossal permittivity in ultrafine grain size BaTiO3−x and Ba0.95La0.05TiO3−x materials. Adv. Mater., 20, 551(2008).

[9] J. Boonlakhorn, N. Chanlek, J. Manyam, P. Srepusharawoot, S. Krongsuk, P. Thongbai. Enhanced giant dielectric properties and improved nonlinear electrical response in acceptor-donor (Al3+, Ta5+)-substituted CaCu3Ti4O12 ceramics. J. Adv. Ceram., 10, 1243(2021).

[10] P. Miao, J. Wang, L. He, L. Zhang. Excellent capacitor varistor properties in lead free CaCu3Ti4O12-SrTiO3 system with a wrinkle structure. ACS Appl. Mater. Interfaces, 43, 48781(2020).

[11] J. Zhang, Y. Li, Q. Yang, Y. Yang, F. Meng, T. Wang, Z. Xia. A structural perspective on giant permittivity CaCu3Ti4O12: One way to quantum dielectric physics in solids. Open Ceram, 6, 2666(2021).

[12] Y. Song, X. Wang, X. Zhang, X. Qi, Z. Liu, L. Zhang, Y. Zhang, Y. Wang, Y. Sui, B. Song. Colossal dielectric permittivity in (Al + Nb) co-doped rutile SnO2 ceramics with low loss at room temperature. Appl. Phys. Lett., 109, 142903(2016).

[13] C. Zhao, J. Wu. Effects of secondary phases on the high-performance colossal permittivity in titanium dioxide ceramics. ACS Appl. Mater. Interfaces, 10, 3680(2018).

[14] J. Li, F. Li, X. Zhu, D. Lin, Q. Li, W. Liu, Z. Xu. Colossal dielectric permittivity in hydrogen-reduced rutile TiO2 crystals. J. Alloys Compd., 692, 375(2017).

[15] M. A. Subramanian, D. Li, N. Duan, B. A. Reisner, A. W. Sleight. High dielectric constant in ACu3Ti4O12 and ACu3Ti3FeO12 phases. J. Solid State Chem., 151, 323(2000).

[16] K. Prompa, E. Swatsitang, T. Putjuso. Very low loss tangent and giant dielectric properties of CaCu3Ti4O12 ceramics prepared by the sol-gel process. J. Mater. Sci.: Mater. Electron., 28, 15033(2017).

[17] D. Lu, X. Yu, J. Liu. Mixed-valent structure, dielectric properties and defect chemistry of Ca1−3x∕2TbxCu3Ti4−xTbxO12 ceramics. Ceram. Int., 43, 8664(2017).

[18] J. Boonlakhorn, P. Kidkhunthod, B. Putasaeng, P. Thongbai. Significantly improved non-Ohmic and giant dielectric properties of CaCu3−xZnxTi4O12 ceramics by enhancing grain boundary response. Ceram. Int., 43, 2705(2017).

[19] Z. Peng, P. Liang, Y. Xiang, H. Peng, X. Chao, Z. Yang. Effect of Zr doping on dielectric properties and grain boundary response of CdCu3Ti4O12 ceramics. Ceram. Int., 44, 20311(2018).

[20] J. Wang, Z. Lu, Z. Chen. The novel effects of Cu-deficient on the dielectric properties and voltage–current nonlinearity in CaCu3Ti4O12 ceramics. Mater. Sci. Eng. B, 243, 1(2019).

[21] J. Boonlakhorn, P. Kidkhunthod, P. Thongbai. Significantly improved giant dielectric response in giant dielectric response in CaCu2.95Ni0.05Ti4−xGexO12 (x=0.05, 0.10) ceramics. Mater. Today Commun., 21, 100633(2019).

[22] J. Boonlakhorn, P. Thongbai. Dielectric properties, nonlinear electrical response and microstructural evolution of CaCu3Ti4−xSnxO12 ceramics prepared by a double ball-milling process. Ceram. Int., 46, 4952(2020).

[23] R. Schmidt, M. C. Stennett, N. C. Hyatt, J. Pokorny, J. Prado-Gonjal, M. Li, D. C. Sinclair. Effects of sintering temperature on the internal barrier layer capacitor (IBLC) structure in CaCu3Ti4O12 (CCTO) ceramics. J. Eur. Ceram. Soc., 32, 3313(2012).

[24] X. Wang, B. Zhang, L. Sun, W. Qiao, Y. Hao, Y. Hu, X. Wang. Colossal dielectric properties in (Ta0.5Al0.5)xTi1−xO2 ceramics. J. Alloys Compd., 745, 856(2018).

[25] J. Li, F. Li, Y. Zhuang, L. Jin, L. Wang, X. Wei, Z. Xu, S. Zhang. Microstructure and dielectric properties of (Nb + In) co-doped rutile TiO2 ceramics. J. Appl. Phys., 116, 074105(2014).

[26] J. Boonlakhorn, P. Srepusharawoot, P. Thongbai. Distinct roles between complex defect clusters and insulating grain boundary on dielectric loss behaviors of (In3+/Ta5+) co-doped CaCu3Ti4O12 ceramics. Results Phys., 16, 102886(2020).

[27] J. Boonlakhorn, P. Thongbai. Substantially enhanced varistor properties and dielectric response in (Zn2+, Sn4+) co-doped CaCu3Ti4O12 ceramics. Ceram. Int., 45, 22596(2019).

[28] B. Guo, P. Liu, X. Cui, Y. Song. Enhancement of breakdown electric field and DC bias of (In0.5Nb0.5)0.005(Ti1−xZrx)0.995O2 colossal permittivity ceramics. J. Alloys Compd., 740, 1108(2018).

[29] J. Sun, C. Xu, X. Zhao, J. Liang, R. Liao. Improved dielectric properties of indium and tantalum co-doped CaCu3Ti4O12 ceramic prepared by spark plasma sintering. IEEE Trans. Dielectr. Electr. Insul., 27, 1400(2020).

[30] H. M. Kotb, M. M. Ahmad, A. Alshoaibi, K. Yamada. Dielectric response and structural analysis of (A3+, Nb5+) cosubstituted CaCu3Ti4O12 ceramics (A: Al and Bi). Materials, 13, 5822(2020).

[31] Z. Peng, D. Wu, P. Liang, X. Zhou, J. Wang, J. Zhu, X. Chao, Z. Yang. Grain boundary engineering that induces ultrahigh permittivity and decreased dielectric loss in CdCu3Ti4O12 ceramics. J. Am. Ceram. Soc., 103, 1230(2019).

[32] Z. Peng, J. Wang, F. Zhang, S. Xu, X. Lei, P. Liang, L. Wei, D. Wu, X. Chao, Z. Yang. High energy storage and colossal permittivity CdCu3Ti4O12 oxide ceramics. Ceram. Int., 48, 4255(2022).

[33] Z. Peng, P. Liang, J. Wang, X. Zhou, J. Zhu, X. Chao, Z. Yang. Interfacial effect inducing thermal stability and dielectric response in CdCu3Ti4O12 ceramics. Solid State Ion., 348(2020).

[34] Z. Peng, P. Liang, X. Chen, Z. Yang, X. Chao. High thermal stability and excellent dielectric properties of a novel X8R-type CdCu3Ti4O12 ceramics through a sol-gel technique. Mater. Res. Bull., 98, 340(2018).

[35] N. Zhao, P. Liang, L. Wei, L. Yang, Z. Yang. Synthesis and dielectric anomalies of CdCu3Ti4O12 ceramics. Ceram. Int., 41, 8501(2015).

[36] L. Yuan, W. Hu, S. Fang, G. Li, X. Wang, X. Wu, W. Han, L. Li. CdO-CuO-TiO2 ternary dielectric systems: Subsolidus phase diagram and the effects of Cu segregation. J. Eur. Ceram. Soc., 38, 4978(2018).

[37] P. Mao, J. Wang, L. Zhang, Z. Wang, F. Kang, S. Liu, D. B. K. Lim, X. Wang, H. Gong. Significantly enhanced breakdown field with high grain boundary resistance and dielectric response in 0.1Na0.5Bi0.5TiO3-0.9BaTiO3 doped CaCu3Ti4O12 ceramics. J. Eur. Ceram. Soc., 40, 3011(2020).

[38] M. A. De La Rubia, P. Leret, A. Del Campo, R. E. Alonso, A. R. López-Garcia, J. F. Fernández, J. De Frutos. Dielectric behaviour of Hf-doped CaCu3Ti4O12 ceramics obtained by conventional synthesis and reactive sintering. J. Eur. Ceram. Soc., 32, 1691(2012).

[39] L. Zhou, Z. Peng, J. Zhu, Q. Shi, P. Liang, L. Wei, D. Wu, X. Chao, Z. Yang. High temperature stability and low dielectric loss in colossal permittivity TiO2 based ceramics co-doped with Ag+ and Mo6+. Mater. Chem. Phys., 295, 127072(2023).

[40] L. Ni, M. Fu, Y. Zhang. Dielectric relaxation and relevant mechanism in giant dielectric constant Sm2∕3Cu3Ti4O12 ceramics. J. Mater. Sci.: Mater. Electron., 29, 17737(2018).

[41] P. Thomas, K. Dwarakanath, K. B. R. Varma, T. R. N. Kutty. Nanoparticles of the giant dielectric material, CaCu3Ti4O12 from a precursor route. J. Phys. Chem. Solids, 69, 2594(2008).

[42] R. Schmidt, S. Pandey, P. Fiorenza, D. C. Sinclair. Non-stoichiometry in “CaCu3Ti4O12” (CCTO) ceramics. RSC Adv., 3, 14580(2013).

[43] P. Kum-Onsa, P. Thongbai, B. Putasaeng, T. Yamwong, S. Maensiri. Na1∕3Ca1∕3Bi1∕3Cu3Ti4O12: A new giant dielectric perovskite ceramic in ACu3Ti4O12 compounds. J. Eur. Ceram. Soc., 35, 1441(2015).

[44] P. Liu, Y. He, J. P. Zhou, C. H. Mu, H. W. Zhang. Dielectric relaxation and giant dielectric constant of Nb-doped CaCu3Ti4O12 ceramics under dc bias voltage. Phys. Status Solidi A, 206, 562(2009).

[45] H. Moreno, J. A. Cortés, F. M. Praxedes, S. M. Freitas, M. V. S. Rezende, A. Z. Simões, V. C. Teixeira, M. A. Ramirez. Tunable photoluminescence of CaCu3Ti4O12 based ceramics modified with tungsten. J. Alloys Compd., 850, 156652(2021).

[46] Z. Li, J. Wu, D. Xiao, J. Zhu, W. Wu. Colossal permittivity in titanium dioxide ceramics modified by tantalum and trivalent elements. Acta Mater., 103, 243(2016).

[47] L. Liu, D. Shi, S. Zheng, Y. Huang, S. Wu, Y. Li, L. Fang, C. Hu. Polaron relaxation and non-ohmic behavior in CaCu3Ti4O12 ceramics with different cooling methods. Mater. Chem. Phys., 139, 844(2013).

[48] C. Wang, W. Ni, D. Zhang, X. Sun, J. Wang, H. Li, N. Zhang. Dielectric properties of pure and Mn-doped CaCu3Ti4O12 ceramics over a wide temperature range. J. Electroceramics, 36, 46(2016).

[49] C.-C. Wang, M.-N. Zhang, K.-B. Xu, G.-J. Wang. Origin of high-temperature relaxor-like behavior in CaCu3Ti4O12. J. Appl. Phys., 112, 034109(2012).

[50] Z. Peng, P. Liang, X. Wang, H. Peng, Y. Xiang, X. Chao, Z. Yang. Copper cadmium titanate prepared by different methods: Phase formation, dielectric properties and relaxor behaviors. Ceram. Int., 44, 7814(2018).

[51] H. Peng, P. Liang, X. Zhou, Z. Peng, Y. Xiang, X. Chao, Z. Yang. Good thermal stability, giant permittivity, and low dielectric loss for X9R-type (Ag1∕4Nb3∕4)0.005Ti0.995O2 ceramics. J. Am. Ceram. Soc., 102, 970(2018).