Ca ₀ 3

The CaCu3Ti4O12 (CCTO), as a new kind of dielectric ceramic material, has excellent dielectric properties. It shows colossal dielectric response with relative permittivity ε up to 104 at room temperature. CCTO simultaneously has good temperature and frequency stability. Since then CCTO has been researched worldwide in the search for miniaturized capacitor devices for applications ranging from large scale energy storage systems to advanced microelectronics. Thus, to develop a new kind of ceramic capacitor devices with CaCu3Ti4O12 materials has remained an interesting topic in ceramic science in recent years. In this work, the CaCu3Ti4O12 ceramic systems were designed and studied by doping to improve electrical properties and stability, Then 2 kg ceramics powder material were prepared, and ceramic capacitor devices with optimal characteristics were successfully fabricated for market applications, which were as follows:1. The Cad(1-x)SrxCu3Ti4O12 systems were designed and prepared by traditional solid phase method. Effect of Sr contents on phase structure, microstructure, dielectric properties of the CCTO ceramics were investigated in detail. The results show that the Ca0.9Sr0.1Cu3Ti4O12 ceramics exhibited the favorable dielectric properties, which were listed as follows:εr=76603, tan δ=0.0386, Eb=0.383 kV/mm, ρ=0.72x106 Ω·cm. The obtained properties make this composition be a good candidate for ceramic capacitor devices.2. The stability of Cad(1-x)SrxCu3Ti4O12 (x=0.00,0.10,0.15,0.25) ceramics placed at room temperature,-20℃,60℃ were studied in detail. The results showed that the properties of the samples at room temperature,-20℃,60℃ can reach a steady state after 25,20,30 days respectively. εr dropped 3.7%～5.8%、0.36%～2.94% and 1.8%～ 7.0% separately, tan δ dropped 1.53%～2.24%、3.79%～9.03% and 0.9%～7.99% respectively. Otherwise, the good temperature stability are obtained in a range of-20℃ to 150℃.3.2 kg Ca0.9Sr0.1Cu3Ti4O12 ceramic powders were prepared. The results showed that the optimal electric properties were obtained with calcined at 900℃ and sintered at 1080℃, which are as follows:εr= 62376, tan δ=0.032, Eb=0.395 kV/mm, ρ= 0.75×106 Ω·cm, respectively. It showed that the performance of Kilogram-Level CSCTO can be comparable to the performance of a small-Level CSCTO, it is also much better than performance of SrTiO3 based powders, indicating that the ceramic capacitor device can be fabricated using this ceramic material.4. The ceramic capacitor devices with Ca0.9Sr0.1Cu3Ti4O12 was fabricated. The results showed that the optimal electric properties were obtained with formed at 160 MPa, poured PVA at 15 h, sintered at 1090℃, holded at 15 h. The ceramic capacitors simultaneously has good temperature and frequency stability.5. The stability of the Ca0.9Sr0.1Cu3Ti4O12 ceramic capacitor devices placed at room temperature,-20℃,60℃ were studied in detail.Theresults showed that the aging stability of Ca0.9Sr0.1Cu3Ti4O12 ceramic capacitors is similar to the small-Level CSCTO, after 3 stages can reach a steady state. The rate of εr change is limited in 10%. After thermal shocking and 5000th CV cycling. All samples follow up with the requested property (Electronic Industry Association standard, EIA standard. TCK< 1% after cycle of charge and discharge). It demonstrates that Ca0.9Sr0.1Cu3Ti4O12 ceramic capacitors have good shocking and cycling stability.