Study On Doping Modification Of Ca CaCu₃Ti₄O₁₂ Dielectric Ceramics

The copper-calcium titanate(Ca Cu₃Ti₄O₁₂,CCTO)has an attractive application prospect in the field of dynamic random access memory?DRAM?large-capacity capacitors and other electronic devices since its properties of a large dielectric constant and better dielectric temperature stability and frequency stability.However,it has a large dielectric loss,which will hinder its practical application.In this work,doped CCTO dielectric ceramics were prepared via conventional solid-state reaction method using Ca CO₃,Cu O,Ti O₂,Mg O,Sr CO₃,and nano-?-Al₂O₃ as raw materials.The effects of Mg O,Sr CO₃,Zn O and nano-Al₂O₃ on properties of CCTO ceramics were analyzed by the X-ray diffraction?XRD?,scanning electron microscopy?SEM?,and dielectric properties testing methods in terms of phase compositions,microstructure,relative density,and dielectric properties.The results show that the dielectric properties of CCTO ceramics are sensitive to the preparation process,doping amount and doping mechanism.For the study of doped Mg at the Cu site in CCTO,the dielectric constant of 1080?Ca Cu_3-x-x Mg_x Ti₄O₁₂?x=0,0.1,0.2?ceramics at 10k Hz is large?10⁵ or more?;and its frequency is stable.However,its dielectric loss is greater?all greater than 0.22?.Ca Cu _3-x-x Mg_x Ti₄O₁₂ceramics sintered at 1110°C have a small amount of glass phase,its dielectric constant is 4?10⁴⁵?10⁴ but its dielectric loss is smaller than that of samples sintered at 1080°C?0.12⁰.2?.Ca Cu_2.8Mg_0.2Ti₄O₁₂sintered at 1110°C for 10h has good dielectric properties and its dielectric constant is 5?10⁴,and its dielectric loss is 0.12 at 10k Hz.For the study of Mg doped in the Ca site of CCTO,the dielectric constant of 1050°C Ca_1-x-x Mg_x Cu₃Ti₄O₁₂ ceramics?x=0,0.05?at 10 k Hz are large?9.5?10³ or more?;and the ceramics have a good frequency stablility.However,its dielectric loss is greater than that of samples sintered at other temperatures?all greater than 0.11?.while the Ca_1-xMg_x Cu₃Ti₄O₁₂ ceramic sintered at 1110°C have a small amount of glass phase,the dielectric constant is 7.8?10³⁹.9?10³ but its dielectric loss is smaller?0.12⁰.2?.Ca Cu₃Ti₄O₁₂ sintered at 1110°C has good dielectric properties;its dielectric constant is 9.9?10³,and its dielectric loss is 0.06 at 10k Hz.For the study of doped Mg O at Cu site of CCTO as well as doped Sr CO₃ at Ca site,the CCTO and Ca_0.9Sr_0.1Cu_2.9.9 Mg_0.1Ti₄O₁₂ sintered at1050°C have a large dielectric constant at 10 k Hz?4?10⁴ or more?.Their frequency stabilities are better,but their dielectric loss is larger?all larger than 0.13?.The CCTO and Ca_0.9Sr_0.1Cu_2.9Mg_0.1Ti₄O₁₂ ceramics sintered at 1110°C have a small amount of glass.Ca Cu_2.9Zn_0.1Ti₄O₁₂2 ceramics was modified by using nano-Al₂O₃.The 0.985 Ca Cu_2.9Zn_0.1Ti₄O₁₂-0.015Al₂O₃ ceramics sintered at 1100°C for 6h have a good dielectric property.Its dielectric constant is 3.8?10⁴at 10k Hz,and its dielectric loss is 0.13.