（Ba_（1－x）K_x）BiO_3芯态能级随组份的变化  

VARIATION OF CORE-LEVEL WITH COMPOSITION IN (Ba_1-xK_x)BiO_3

作　　者：沈耀文[1] 陈龙海[1] 黄美纯[1] 

机构地区：[1]厦门大学物理系

出　　处：《低温物理学报》1995年第3期201-208,共8页Low Temperature Physical Letters

基　　金：国家自然科学;福建省自然科学基金

摘　　要：本文用第一原理的ＬＤＦ－ＬＭＴＯ－ＡＳＡ方法，以超元胞Ｂａ４Ｂｉ４Ｏ（１２），（Ｂａ３Ｋ）Ｂｉ４Ｏ（１２），（ＢａＫ）Ｂｉ２Ｏ６，（ＢａＫ３）Ｂｉ４Ｏ（１２），Ｋ２Ｂｉ２Ｏ６五种“样本”计算由于Ｂｉ（＋３）和Ｂｉ（＋５）二种价态以及Ｋ掺杂引起各芯态能级化学位移的变化．“样本”的电子结构与实验相符，即Ｂａ４Ｂｉ４Ｏ（１２）是Ｅｇ＝２．０ｅＶ的半导体，（Ｂａ３Ｋ）Ｂｉ４Ｏ１２是Ｅｇ＝１．６ｅＶ其价带顶有少量空穴的半导体．其余“样本”是金属．芯态的ＬＤＦ本征值经原子模型△ＳＣＦ修正更接近实验值．用正态分布表达各芯态能级除化学位移外各种“环境因子”的影响，结合任意组份五种“样本”的伯努利分布，计算芯态电子能谱随ｘ的变化．结果表明，所有芯态的自旋一轨道分裂与实验完全相符，Ｂｉ（＋３）和Ｂｉ（＋５）二种价态引起各芯态化学位移的变化均小于０．２ｅＶ，Ｋ掺杂使各芯态结合能略有增加，其中Ｂｉ（４ｆ），Ｂａ（５ｄ）约１．３～１．５ｅＶ，其他芯态约０．４ｅＶ，以上计算结果与实验基本一致．Abstract Chemical shift of core level for (Ba1-xKx )BiO3 due to the exist of Bi+5 and Bi+3 and the doping of patassium has been calculated by the LDF-LMTO-ASA-△SCF method via five supercells, i. e., Ba4Bi4O12, (Ba3K ) Bi4O12, (BaK ) Bi2O6, (BaK3 ) Bi4O12, and K2Bi2O6. Present calculations show that the first and second samples are semiconductors with the bandgap of 2. oeV and 1. 6eV respectively, other three samples are metals, Which are in consistent with the experimental data. The LDF eigenvalues the of core level from the △SCF method of atomic model are in better agreement with the experiments. The photoemission spectra are obtained using a Bernoulli's distribution for the five supercells to describe the sampling propability of patassium doping under a certain configuation x,and a normal distribution for describing the effect of the width of core level due to environmental factors. The spin(orbit splitting data are in good accord with the experiments. The chemical shift due to the exist of two unequal Bisiters are less than 0. 2eV. Core state cohesive energies are slightly increased by the dOPing of K,e. g., for Bi4f and Ba5d the cohesive energy is increased be 1. 3- 1. 5eV, for others less than 0. 4eV, all these data are in agreement with the experiments.

关 键 词：超元胞 芯态能级 化学位移 K掺杂 

分 类 号：O561.2[理学—原子与分子物理]