纳米金红石相TiO_2块体的介电特性研究

Dielectric Behavior of Nanostructured Rutile-phase TiO_2 Bulk

在大气和真空条件下 ,对纳米金红石相TiO2 块体进行介电频谱测试。发现样品在大气中的相对介电常数比其在真空中的数值高 10 2 ～ 10 3 倍 ;大气中介电损耗高于其在真空中的数值 ,大气中频率约在 3kHz时出现损耗最小值 ,真空中介电损耗则随频率增加而单调减小。分析认为纳米金红石相TiO2 介电常数异常是由材料界面中的缺陷和悬键所引起的。在大气中 ,纳米金红石TiO2 的介电损耗以极化损耗 (电偶极矩转向极化和离子弛豫极化 )为主 ,而在真空中则以电导损耗为主。

The spectra of dielectric constant and the dielectric loss of the nanostructured rutile-phase TiO 2 powder compacts were measured in vacuum and in air,respectively,with a ZL-5 LCR Tester.The results show that the dielectric constant of the sample measured in vacuum is 10 2～10 3 times higher than that evaluated in air,but its dielectric loss in vacuum is lower than that in air.The dielectric loss in air reaches its minimum at a frequency of 3 kHz,whereas in vacuum,it decreases monotonously with the increase of frequency.We suggest that the observed anomaly in the dielectric constant may originate from defects and dangling bonds at grain boundaries.In air,ion relaxation polarization strongly affects the dielectric loss,whereas in vacuum,the dielectric loss depends heavily on electric conductance.