Sr掺杂对12CaO·7Al_2O_3电子化合物电输运及发射性能的影响  

Effect of Sr Doping on Electrical Transport and Emission of 12CaO·7Al_2O_3 Electride

作　　者：赵伟康 张忻[1] 冯琦 赵吉平 刘洪亮[1] 李凡 肖怡新 刘燕琴[1] 张久兴[1,2] ZHAO Wei-Kang;ZHANG Xin;FENG Qi;ZHAO Ji-Ping;LIU Hong-Liang;LI Fan;XIAO Yi-Xin;LIU Yan-Qin;ZHANG Jiu-Xing(Key Laboratory of Advanced Functional Materials,Ministry of Education,College of Materials Science and Engineering,Beijing University of Technology,Beijing 100124,China;School of Materials Science and Engineering,Hefei University of Technology,Hefei 230009,China)

机构地区：[1]北京工业大学材料科学与工程学院新型功能材料教育部重点实验室,北京100124 [2]合肥工业大学材料科学与工程学院,合肥230009

出　　处：《无机材料学报》2019年第5期521-528,共8页Journal of Inorganic Materials

基　　金：国家自然科学基金(51371010;51572066;50801002);北京市自然科学基金(2112007)~~

摘　　要：12CaO·7Al_2O_3电子化合物(C12A7:e~–)是一种具有低工作温度和低逸出功等优点的新型电子化合物阴极材料。通过高温固相反应结合放电等离子烧结制备Sr掺杂(Ca_(1–x)Sr_x)12A7 (0≤x≤0.05)块体,并在1100℃采用Ti颗粒还原20h成功制得电子化合物(Ca_(1–x)Sr)x)12A7:e~–。第一性原理计算结果表明,(Ca_(1–x)Sr_x)12A7:e~–与C12A7:e~–相比,框架导带下移,费米能级附近态密度增加,这将有利于电输运和发射性能的优化。室温电输运测试结果表明, Sr掺杂有利于C12A7:e–电输运性能的优化,其中(Ca_(0.96)Sr_(0.04))12A7:e~–样品在室温下具有最高电导率(1136 S/cm)以及最高载流子浓度(2.13×1021 cm^(–3)),与相同条件下制备的C12A7:e–样品相比,载流子浓度提高近2个数量级,表明Sr掺杂可以有效缩短制备C12A7:e~–的制备时间。热电子发射性能测试结果表明,随着Sr掺杂量的增加,热电子发射性能逐渐提高,其中(Ca_(0.96)Sr_(0.04))12A7:e~–样品具有最佳的热发射性能,在1100℃外加电压3500V时,发射电流密度达到1.45A/cm^2,零场发射电流密度达到0.74 A/cm^2,理查生逸出功降低至1.86 eV。[Ca24Al28O64]^4+:4e–(C12A7:e–) is a new cathode material with low working temperature and low work function, and its unique cage structure attracts attention of researchers. In this work, the Sr doped (C1–xSx)12A7:e– (0≤x≤0.05) were prepared by high temperature solid phase reaction combined with spark plasma sintering (SPS), and the electron compound (Ca1–xSrx)12A7:e– was successfully obtained by reduction of Ti particles at 1100 ℃ for 20 h. The first principle calculations for electronic structure show that Sr doping changes the band structure of C12A7:e–, the Framework Conduction Band (FCB) decreases to 0.3 eV, benefits the electrical properties of (Ca1–xSrx)12A7:e–. The total density of states (DOS) of (Ca1–xSrx)12A7:e– near the Fermi energy level is increased. The electrical transport characteristics test results show that the (Ca0.96Sr0.04)12A7:e– has the highest conductivity 1136 S/cm and carrier concentration (2.13±0.11)×10^21 cm^–3, indicating that Sr doping is benefical for reducing the preparation time of mayenite electride. The thermionic emission performance test results show that Sr doping significantly increases the emission current density and effectively reduces the average effective work function. The (Ca0.96Sr0.04)12A7:e– has the best emission performance, and the emission current density reaches 1.45 A/cm^2 at 1100 ℃ and a anode voltage of 3500 V. The Zero field emission current density is 0.74 A/cm^2, and the Richardson work function reduces from 2.01 eV (un-doped) to 1.86 eV.

关 键 词：12CaO·7Al2O3电子化合物 Sr掺杂 电输运 发射性能 

分 类 号：TQ174[化学工程—陶瓷工业]