Bi_2O_3掺杂对Ni-Mn-O基NTC热敏陶瓷显微结构及电性能的影响

Effects of Bi_2O_3 doping on microstructure and electrical properties of Ni-Mn-O based NTC ceramics

采用固相配位反应法制备Ni0.6BixMn2.4-xO4(0≤x≤0.1)热敏陶瓷。采用X线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)和阻抗分析仪对陶瓷的相结构、显微结构、元素分布和电性能进行表征。结果表明:少量添加Bi2O3能显著提高材料的烧结性能,在1 000℃下达到致密化。在x=0时,材料保持单相立方尖晶石结构,当x≥0.02时,有杂相Bi2O3、Bi3.64Ni0.36O5.82、Bi7.47Ni0.53O11.73及Bi2Ni2O5相继出现。随着Bi3+掺杂量的增加,陶瓷晶粒尺寸先增大后减小,伴随着显微结构的变化,材料的电阻率先减小后增大,材料常数B先增大后减小。

Ni0. 6BixMn2. 4- xO4（ 0≤x≤0. 1） ceramics were prepared by solid-state coordination reaction. The phase,microstructure,elements distribution,and electrical properties were investigated by X-ray diffraction（ XRD）,scanning electron microscope（ SEM）,energy disperse spectroscopy（ EDS）,and precision impedance analyzer,respectively. Results showed that the sintering performance of the ceramic was improved by adding a small amount of Bi2O3,and dense ceramics obtained at 1 000 ℃. When x = 0,the ceramic was single cubic spinel structure. The mixed phases,Bi2O3,Bi3. 64Ni0. 36O5. 82,Bi7. 47Ni0. 53O11. 73,and Bi2Ni2O5,appeared one by one while x≥0. 02. As the Bi3 ＋content increased,the grain size increased firstly,and then decreased. The electrical resistivities decreased with the increasing of Bi3 ＋content（ 0≤x≤0. 08）,then turned to increase with the increasing of Bi3 ＋content（ 0. 08 x ≤0. 1）. The material constant B increased firstly,and then decreased.