稀土氧化物Eu_2O_3掺杂对CaCu_3 Ti_4O_(12)陶瓷微结构及介电特性的影响

Effect of Eu_2O_3 doping on the microstructure and dielectric characteristics of CaCu_3 Ti_4O_(12) ceramics

以稀土氧化物Eu2O3为添加剂,采用固相反应法制备了不同掺杂比例(质量比:x=0,0.2%,0.5%,1%)的CCTO陶瓷样品,利用SEM、XRD、4294A型高精密阻抗分析仪等测试手段对样品的微观结构、介电性能和交流电阻率进行了测试分析。掺杂之后样品的晶格结构并未发生改变,但是样品内部相对晶相含量和晶粒平均尺寸减小,同时掺杂阻碍了样品内部晶界处富铜相的生成;纯CCTO的XRD图谱中分别出现了CuO、TiO2和CaCO3杂相,掺杂样品的图谱中并未出现上述杂相;样品的介电性能与相同组分材料内部的相对晶相含量,晶粒平均尺寸和晶界处富铜相有很大关系。Eu2O3掺杂提高了样品介电性能的频率和温度稳定性。当掺杂量为0.2%和0.5%时,样品的介电性能得到较好改善效果。样品在低频40Hz和高频3.5MHz的交流电阻率测量结果很好的验证了Eu2O3掺杂导致的微结构变化对样品介电性能的影响。

The CaCu3Ti4O12 ceramics doped by Eu203 with different dopant contents （w% x =0,0.2% ,0. 5%, 1% ） are prepared by the traditional solid -state reaction method. SEM, XRD and Agilent 4294A Precision Impedance Analyzer are used to measure the phase structure, the morphology, dielectric properties and the ac resistivity of the samples. The results show that the crystal structures of CCTO doped by Eu2O3 are similar to that of pure CCTO. But Eu2O3 - dopping can decrease the relative content of crystals in the CCTO ceramics with identical component and the average grain size and can also deter the formation of Cu -enriched phase in the grain boundary. The second phases of CuO,TiO2 and CaCO3 are present in the XRD pattern of pure CCTO and disappear in that of the samples doped by Eu2O3. In addition, it has been found that the dielectric properties of CCTO ceramics are greatly associated with the relative content of crystals in the CCTO ceramics with identical component, the average grain size and Cu - enriched phase in grain boundary. Eu2O3 -dopping can improve the frequency and temperature stability of dielectric properties of the materials. The better improvement to the dielectric properties is achieved by doping 0.2w% and 0.5% of Eu203. The effect of microstructure changing on the dielectric properties after being doped by Eu2O3 has been well confirmed by the ac resistivity of samples measured at 40Hz and 3.5MHz respectively.