高压下TiO_(2)纳米线晶粒和晶界性质及电输运行为  

Grain and grain boundary behaviors and electrical transport properties of TiO_(2) nanowires under high pressure

作　　者：王月[1] 邵渤淮 陈双龙[1] 王春杰[1] 高春晓[2] Wang Yue;Shao Bo-Huai;Chen Shuang-Long;Wang Chun-Jie;Gao Chun-Xiao(College of Physical Science and Technology,Bohai University,Jinzhou 121013,China;State Key Laboratory of Superhard Materials,Jilin University,Changchun 130012,China)

机构地区：[1]渤海大学物理科学与技术学院,锦州121013 [2]吉林大学,超硬材料国家重点实验室,长春130012

出　　处：《物理学报》2022年第9期226-233,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12004050);辽宁省教育厅项目(批准号:LJ2019013,LQ2020005)资助的课题。

摘　　要：采用水热合成法制备了锐钛矿相TiO_(2)纳米线,并通过原位高压阻抗谱测量技术研究了TiO_(2)纳米线晶粒和晶界性质及电输运行为随压力的变化关系.研究结果表明:在0—34.0 GPa压力区间,锐钛矿TiO_(2)纳米线的传导机制为电子电导.TiO_(2)纳米线晶粒和晶界电阻以及弛豫频率在8.2—11.2 GPa压力区间均出现了不连续变化行为,此压力区域对应着由锐钛矿相到斜锆石相的结构转变,并且相变从晶粒表面逐渐延伸到晶粒内部.晶粒激活能和晶界激活能均随压力的增加而减小,说明压力对样品电导率的贡献为正.在所测压力范围内,空间电荷势始终为正值,表明在空间电荷区阴离子缺陷更易形成,氧缺陷是TiO_(2)纳米线相变的主要诱因.In this work,anatase Titanium dioxide(TiO_(2)) nanowires are synthesized by the hydrothermal method,and its grain and grain boundary behaviors and electrical properties are investigated by alternating current(AC)impedance method under high pressure(up to 34.0 GPa).The relationship between the frequency dependence of impedance Z"and pressure indicate that the conduction mechanism of anatase phase TiO_(2) nanowires in the test pressure range is electronic conductivity.It should be noted that the characteristic peaks of Z"move toward high frequency region with pressure increasing,demonstrating that the effect of grain interior on impedance becomes apparent.Additionally,the overall variation trends of grain and grain boundary resistance go downward with pressure increasing,and the descent rate of grain boundary is larger than those of grain before and after phase transition.However,in a range of phase transition(8.2-11.2 GPa,from anatase to baddeleyite phase),grain boundary resistance shows a discontinuously change(increases to 11.2 GPa and then decreases).Based on the different variation trends of grain and grain boundary resistance,it becomes obvious that the phase transition from anatase to baddeleyite phase first occurs at the surface of grain,and then extends to the interior of grain gradually.Also,as an intrinsic characteristic,the relaxation frequency is independent of the geometrical parameters.The pressure dependence of activation energy is obtained by fitting the pressure dependence of relaxation frequency.The activation energy of grain and grain boundary decrease with pressure increasing,implying that the contribution of pressure on the conductivity of sample is positive.Furthermore,the space charge potential for the whole test pressure range is positive,which is determined by the relationship between pressure and relaxation frequency.This fact illustrates that the anion defects are easily formed in the space charge region,and the oxygen defects are the main inducement for TiO_(2) phase transformation.

关 键 词：高压 TiO_(2)纳米线 阻抗谱 电子电导 

分 类 号：TQ134.11[化学工程—无机化工] TB383.1[一般工业技术—材料科学与工程]