Co掺杂氧化锌的电学和磁学性质的研究

Electrical and Magnetic Properties of Co-doped ZnO

采用水热合成法实现了Co掺杂氧化锌材料,并对所制备的材料以及在空气中退火材料的电学和磁学性质进行了研究。通过X射线衍射(XRD)、扫描电镜(SEM)等方法对制得样品的结构、形貌进行了表征,结果表明:Zn_(0.9)Co_(0.1)O为六方纤锌矿结构,钴元素的掺入并不改变氧化锌的物相结构。由于掺杂过程中钴元素替代晶格中锌离子的位置,晶格常数发生了改变,同时也影响了材料的性质;退火后样品的晶粒尺寸减小,结晶性变得更好。通过霍尔效应测试系统对样品的电输运性质和磁阻效应进行了分析,结果表明初始样品零场电阻大于退火后样品。磁场对样品内的载流子浓度和迁移率产生了影响,从而影响样品的电导率。两组样品均表现为正磁阻效应,这主要是由于电子局域化作用和能带劈裂效应共同作用的结果,初始样品受到内部晶格缺陷影响,磁阻效应没有持续增加,而经退火处理后的样品内部晶格缺陷减少,水分子导电作用减弱,致使正磁阻作用越来越明显。

Electrical and magnetic properties of Co doping ZnO prepared by simple hydrothermal method were studied.To determine the structure,morphological and properties of sample,some investigation measurements were used,such as XRD,SEM and so on.The XRD results show that Co ions incorporates into the ZnO lattice successfully with 2 ＋ valence state,without formatting any detectable secondary phase and the substitution of Co2＋ for Zn2＋ does not change the original wurtzite structure of zinc oxide.For Co doped ZnO,the length and diameter was found to decrease,the reason is Co ion radius was smaller than the ironic radius of Zn.Compared with the sample unannealed,the lattice size after annealing of the sample is reduced,the crystallinity becomes better,it is reason for that anneal reduced lattice internal defects,and anneal temperature is more beneficial to the growth of crystal.The electrical transport properties and magnetoresistance（MR） effect results indicated that unannealed sample resistance is greater than annealed sample in zero magnetic field.Applied magnetic field on the sample has crucial effect on the carrier concentration and Hall mobility.All samples showed positive MR effect,which is mainly due to electron and photon localization results of band splitting the combined action.Because of the influence of internal lattice defects,unannealed sample has no sustained increase in the range of magnetic field,and the value is smaller.The reason is that annealing made lattice internal defects decreased and the water molecules conductive effect weakened,resulting in a positivemagnetoresistance effect more obvious but the value is decrease.