Mg掺杂增强CuCrO_(2)陶瓷的电传导及各向异性  

Enhancing the Electrical Conductivity and Anisotropy of CuCrO_(2) Ceramics by Mg^(2+) Doping

作　　者：孟佳源 李毅 赵裕春 武浩荣 汪雪松 骆婉君 虞澜[1] MENG Jiayuan;LI Yi;ZHAO Yuchun;WU Haorong;WANG Xuesong;LUO Wanjun;YU Lan(Faculty of Materials Science and Engineering,Kunming University of Science and Technology,Kunming 650093,China)

机构地区：[1]昆明理工大学材料科学与工程学院,昆明650093

出　　处：《人工晶体学报》2024年第1期163-169,共7页Journal of Synthetic Crystals

基　　金：国家自然科学基金(51962017,51462017)。

摘　　要：采用固相反应法制备了具有c轴择优的CuCr_(1-x)Mg_(x)O_(2)(x=0、0.005、0.010、0.020、0.030、0.040、0.050)系列多晶,分别从垂直和平行于压力的宏观面内方向和厚度方向研究Mg掺杂对CuCrO_(2)多晶微结构取向和电性能及各向异性的影响,探讨了Mg掺杂增强CuCrO_(2)陶瓷电导率各向异性的机制。当x≤0.030时,多晶为菱方R3m单相结构,随着掺杂量的增加,晶粒在面内充分长大,气孔和晶界减少,致密度逐渐提高,多晶呈现热激活半导体电输运行为;当x=0.030时,面内取向因子F((00l))达到最高值0.912,面内c轴择优取向远优于厚度方向,面内和厚度方向的CuCr_(1-x)Mg_(x)O_(2)多晶室温电阻率分别显著下降至1.80×10^(-3)和3.16×10^(-3)Ω·m,这是由于其结构各向异性的差异,热激活能均减小至0.03 eV,c轴择优取向对热激活能影响并不明显,最大载流子浓度比母相均增加3个量级,晶界缺陷更少,平均自由程增大,输运能力更强,电导率更高。实验表明最优掺杂量为x=0.030,当掺杂量x高于0.030时,出现MgCr_(2)O_(4)尖晶石杂相,样品的微观结构和电输运性能变差。CuCr_(1-x)Mg_(x)O_(2)(x=0,0.005,0.010,0.020,0.030,0.040,0.050)polycrystals with c-axis preferred orientation were prepared by solid phase reaction method.The effects of Mg^(2+) doping on the microstructure orientation,electrical properties,and anisotropy of CuCrO_(2) polycrystals from the vertical and parallel macroscopic in-plane and thickness directions were investigated.The mechanism of Mg doping enhancing the anisotropy of the electrical conductivity in CuCrO_(2) ceramics was explored.When x≤0.030,the polycrystals exhibit a rhombohedral R3m single-phase structure,with grain growth predominantly occurring within the surface plane.This led to a reduction in the presence of gas pores and grain boundaries,resulting in the increase of density.The polycrystals demonstrated thermally activated semiconductor electrical transport behavior.When x=0.030,the in-plane orientation factor F_((00l))reaches its highest value of 0.912,indicating a significantly enhanced c-axis preferred orientation within the surface plane compared to the thickness direction.The room temperature resistivity of CuCr_(1-x)Mg_(x)O_(2) polycrystals in the in-plane and thickness directions decrease significantly to 1.80×10^(-3)and 3.16×10^(-3)Ω·m,respectively.This difference in electrical performance between the two directions was closely related to the structural anisotropy.The thermal activation energy decreased to 0.03 eV,and the c-axis preferred orientation has no significant influence on the thermal activation energy.The maximum carrier concentration increase by three orders of magnitude compared to the parent phase,indicating fewer grain boundary defects,an increased average free path,enhanced transport capacity,and higher conductivity.The experimental results reveal that the optimal doping concentration is x=0.030.When the doping level exceeded 0.030,the spinel phase MgCr_(2)O_(4) appeared as an impurity,resulting in a deterioration of the microstructure and electrical transport properties of the samples.

关 键 词：c轴择优 CuCr_(1-x)Mg_(x)O_(2)多晶 各向异性 电阻率 晶界缺陷 电输运 

分 类 号：TB34[一般工业技术—材料科学与工程] TQ174[化学工程—陶瓷工业]