Research On Dielectric Properties And Electrical Transport Behavior Of Doping CaCu₃Ti₄O₁₂Ceramic

Giant dielectric constant usually means a material having a high energy density,The high energy density is an important factor,which affect electronic components capacitors, detectors, information storage. So the study of giant dielectric constant of the material is expected to be a breakthrough in improving the capacity of the capacitor and achieve miniaturization of electronic components.In this context, this paper uses solid state reaction method successfully prepared the doping of CCTO ceramics,In the microstructure and properties as well as other aspects of the mechanism for the doping of CCTO ceramics were studied.Firstly, by the method of the solid phase synthesis, Al and Li, Al element commonly doping CCTO ceramics were prepared. Al doping CCTO ceramics using Al element replacement CCTO part of Cu element, which is equivalent to CCTO ceramics donor doping, and researching microstructure and dielectric properties of the different amount and the different sintering time of Al elements doping. With the increase of Al doping content, the dielectric constant of CCTO ceramics have been significantly improved. When Frequency is 100 Hz, Al doping content at 1wt%, CCTO dielectric constant up 8.7 × 104. Compared to undoped ceramic,CCTO dielectric constant doubling and giant dielectric constant have good frequency stability. When Al doping amount to 2wt%, the dielectric constant reaches 3 × 105. It needs to be noted that, Ceramic samples Appeared the Phenomenon of Class Debye relaxation at low frequency(~ 105Hz) and high frequency(~ 107Hz). Meanwhile, with the extension of the sintering time, Al doping amount of 1 wt% CCTO ceramic permittivity gradually increase, when sintering time is 20 h, dielectric constant of Ceramic up 1.03 × 105. CCTO ceramics of Li, Al co-doping, with the increase of doping content, the dielectric constant increases, When the doping content of 5wt% and 10wt%, at 100 Hz frequency, the dielectric constant was 9.3 × 104 and 4.8 × 105, And accompanied by two relaxation dispersion peak.Doping CCTO ceramics lead to internal oxygen vacancies generated contribution to the dielectric constant by interfacial polarization. And with the increase of doping content, the carrier concentration increases, reducing the grain boundary resistance, and resulting in the low frequency portion of the ceramic dielectric constant significantly. Doping leads to Cu1 + / Cu2 + and Ti3 + / Ti4 + ions appear with mixed-valence structure, which will produce more micro Polaron enhanced polarization response and will increase the dielectric constant. By measuring the ultraviolet spectrum, Experiment study the change of the forbidden band gap change of donor doping of Al elements, With the increase in doping, the forbidden band gap basically showing decreasing trend, whose forbidden band gap reduced by the 1.92 e V to 1.85 e V. by analyzing the UV spectrum measurement results, With the increase of Al doping, ceramics absorb ligh t wavelength becomes longer, Al-doped test confirmed CCTO ceramic band gap decreases. with the increase in doping content, dc conductivity of Al-doped CCTO ceramic gradually increases. Corresponding the activation energy decreases. Further evidence of the Al-doped increases the carrier concentration in ceramics, reducing the band gap.