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化学学报
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化学学报 ›› 2011, Vol. 69 ›› Issue (17): 1973-1979. 上一篇    下一篇

研究论文

低温相GeO2晶体的合成及其电子结构与光学性质第一性原理计算

荣成*，蔡向阳，蒋疆   

  1. (福建农林大学生命科学学院应用化学系 福州 350002)
  • 投稿日期:2010-11-09 修回日期:2011-04-06 发布日期:2011-05-11
  • 通讯作者: 荣成 E-mail:rongch@fjau.edu.cn
  • 基金资助:

    福建教育厅科技基金;福建农林大学青年教师基金

Synthesis and First-Principle Calculation of Electronic Structure and Optical Properties of Low Temperature Phase GeO2 Crystal

RONG Cheng, CAI Xiang-Yang, JIANG Jiang   

  1. (Department of Applied Chemistry, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002)
  • Received:2010-11-09 Revised:2011-04-06 Published:2011-05-11
  • Contact: Cheng RONG E-mail:rongch@fjau.edu.cn

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通过低温水热的合成方法合成了一例新的低温相GeO2晶体(l-GeO2), 并对其进行了红外光谱、热重以及X射线衍射的分析表征. 晶体学测试结果表明, l-GeO2属于四方晶系, P4/mcc空间群, 晶胞参数a＝b＝8.832(4) Å, c＝14.479(7) Å, V＝1129.4(9) Å3, Z＝4, R1＝0.0629, wR2＝0.1540. 晶体结构中包含一个由4个双四元环单元(D4R)和4个GeO4四面体交替相连而形成的沿[001]方向的一维(1D) 12-元环孔道. 采用密度泛函理论下的第一性原理平面波超软赝势方法, 对l-GeO2的电子结构和光学性质进行了理论计算. 计算结果表明l-GeO2为直接带隙半导体, 带宽为3.31 eV|其价带主要由O的2p电子构成, 导带主要由Ge的4s和4p态电子构成|静态介电常数ε1(0)＝1.92, 折射率n(0)＝1.24, 吸收系数最大峰值为8.9×104 cm－1, 最大反射率为12%. 比较分析了l-GeO2与石英相GeO2 (q-GeO2)和金红石相GeO2 (r-GeO2)的复介电函数、复折射率、吸收谱以及反射谱等光学性质的异同点. 结果显示l-GeO2的能带结构和光学性质与q-GeO2较接近, 与r-GeO2的相差较大.

关键词: 低温相, 电子结构, 光学性质, 第一性原理

A novel low temperature phase l-GeO2 crystal has been synthesized under hydrothermal conditions and characterized by means of IR spectrum, thermogravimetric (TG) analysis and X-ray diffraction. a＝b＝8.832(4) Å, c＝14.479(7) Å, V＝1129.4(9) Å3, Z＝4, R1＝0.0629, wR2＝0.1540. The 1D 12-member ring channels along the [001] direction are formed by the alternate linking of D4R units and GeO4 tetrahedra in l-GeO2. The electronic structure and optical response functions of l-GeO2 were calculated by using a first-principle ultra-soft pseudo-potential approach of the plane wave based upon density functional theory (DFT). The results show that: l-GeO2 is a direct semiconductor with a band gap of 3.31 eV. The density of state of l-GeO2 is mainly composed of Ge 4s, 4p and O 2p with the static dielectric function ε1(0) of 1.92, the refractive index n(0) of 1.24, the maximum absoption coefficient of 8.9×104 cm－1 and the maximum reflectivity of 12%. Moreover, the same and different points of dielectric functions, refractive index, absorption spectra and reflection spectra of l-GeO2, q-GeO2 and r-GeO2 are compared. The results indicate that the band structures and optical properties of l-GeO2 are similar to that of q-GeO2 but much difference to that of r-GeO2.

Key words: low temperature phase, electronic structure, optical property, the first-principle