BaCo_xZn_(2-x)Fe_(16)O_(27)六角铁氧体电子结构与介电特性的第一性原理研究  

Electronic structures and dielectric properties of BaCo_xZn_(2-x)Fe_(16)O_(27) from first principles

作　　者：李忠虎[1,2] 李林[1] 祁阳[3] 

机构地区：[1]东北大学理学院物理系,沈阳110819 [2]朝鲜理科大学物理系 [3]东北大学理学院材料物理与化学研究所,沈阳110819

出　　处：《物理学报》2012年第20期403-409,共7页Acta Physica Sinica

基　　金：国家重点基础研究发展计划(批准号:2011CB606404);国家自然科学基金(批准号:10874022);中国科学院"十一五"信息化专项(批准号:INFO-115-B01)资助的课题~~

摘　　要：提出了W型六角铁氧体BaCo_xZn_(2-x)Fe_(16)O_(27)的晶体结构模型,并通过基于密度泛函理论框架下Hubbard参数U修正的广义梯度近似密度泛函理论方法研究了该材料的基态电子结构、磁性和静电介电性特性.Co和Zn共掺杂引起BaFe_(18)O_(27)的导电性从半金属转换到半导体.BaCo_xZn_(2-x)Fe_(16)O_(27)的能隙随x增加而增加,品格常数和原胞磁矩随之而变小.介电常数计算表明,BaCo_xZn_(2-x)Fe_(16)O_(27)的静电介电常数随x增加而增加,在6.2—7.2范围而且显示各向异性.Bom电荷计算分析表明Co和Zn本身极化对材料的介电常数和其各向异性影响不大.On the basis of the crystal structure model of BaCoxZn2-xFe16O27, their ground electronic states and dielectric properties have been investigated using the generalized gradient approximation plus Hubbard U approach. The co-substitutions of cobalt and zinc cause the electrical conductivity of BaFe18O27 to change from a half-metallic to semiconductive. With the increase of Co content x, the energy gap of BaCoxZn2-xFe16O27 increases but the lattice constants and the magnetic moment of the unit cell decrease. The calculations of dielectric constants show that the static dielectric constants increase with x, lie in a range of 6.2-7.2 and appear to be anisotropic. Through the Born electric charge analysis it is shown that the polarization of Co and Zn itself has little effect on the polarization of the material and the main polarization may be related to the polarization of the iron and oxygen ions, caused by the crystal distortion.

关 键 词：W型六角铁氧体 第一性原理 电子结构 介电特性 

分 类 号：TM277[一般工业技术—材料科学与工程]