Reshak Ali Hussain, Auluck S, Kityk I V, Chen Xuean
Institute of Physical Biology, South Bohemia University, Nove Hrady 37333, Czech Republic.
J Phys Chem B. 2009 Jul 9;113(27):9161-7. doi: 10.1021/jp903170p.
We report results of X-ray diffraction (XRD) and valence band X- ray photoelectron (VB-XPS) spectra for strontium borate Sr(2)B(16)O(26). The X-ray structural analysis shows that the single crystals of Sr(2)B(16)O(26) crystallize in the monoclinic space group P2(1)/c with a = 8.408(1) A, b = 16.672(1) A, c = 13.901(2) A, beta = 106.33(1) degrees , and Z = 4. The crystal structure consists of a 3D network of the complex borate anion B(16)O(20)O(12/2), formed by 12 BO(3) triangles and four BO(4) tetrahedra, which can be viewed as three linked B(3)O(3)O(4/2) triborate groups bonded to one pentaborate B(5)O(6)O(4/2) group and two BO(3) triangles. Using this structure, we have performed theoretical calculations using the all-electron full potential linearized augmented plane wave (FP-LAPW) method for the band structure, density of states, electron charge density, and the frequency-dependent optical properties. Our experimental VB-XPS of Sr(2)B(16)O(26) is compared with results of our FP-LAPW calculations. Our calculations show that the valence band maximum (VBM) and conduction band minimum (CBM) are located at Gamma of the Brillouin zone (BZ) resulting in a direct energy gap of about 5.31 eV. Our measured VB-XPS show reasonable agreement with our calculated total density of states for the valence band that is attributed to the use of the full potential method.
我们报告了硼酸锶Sr₂B₁₆O₂₆的X射线衍射（XRD）和价带X射线光电子能谱（VB-XPS）结果。X射线结构分析表明，Sr₂B₁₆O₂₆单晶属于单斜空间群P2₁/c，a = 8.408(1) Å，b = 16.672(1) Å，c = 13.901(2) Å，β = 106.33(1)°，Z = 4。晶体结构由复杂硼酸盐阴离子[B₁₆O₂₀O₁₂/₂]⁴⁻的三维网络组成，该阴离子由12个BO₃三角形和4个BO₄四面体形成，可看作是三个相连的[B₃O₃O₄/₂]⁻三硼酸盐基团与一个五硼酸盐[B₅O₆O₄/₂]⁻基团以及两个BO₃三角形相连。利用该结构，我们采用全电子全势线性缀加平面波（FP-LAPW）方法对能带结构、态密度、电子电荷密度以及频率相关的光学性质进行了理论计算。我们将Sr₂B₁₆O₂₆的实验VB-XPS与FP-LAPW计算结果进行了比较。我们的计算表明，价带最大值（VBM）和导带最小值（CBM）位于布里渊区（BZ）的Γ点，导致直接能隙约为5.31 eV。我们测量的VB-XPS与计算得到的价带总态密度显示出合理的一致性，这归因于全势方法的使用。
