Electronic structure and electron energy-loss spectroscopy of ZrO2 zirconia -: art. no. 245116
Electronic structure and electron energy-loss spectroscopy of ZrO2 zirconia -: art. no. 245116
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DOI：
10.1103/physrevb.70.245116
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发表时间：
2004-12-01
影响因子：
3.7
通讯作者：
Reining, L
中科院分区：
文献类型：
--
作者：
Dash, LK;Vast, N;Reining, L
氧化锆的原子和电子结构的密度泛函理论内计算，并分析其演变的晶体场对称性的变化从四面体[立方（c-ZrO 2）和tetraxide（t-ZrO 2）相]八面体（假设金红石ZrO 2），这些对称性的混合（单斜相，m-ZrO 2）。我们发现，在c-ZrO 2的理论体积模量是30%以上的实验值，表明在氧化锆中的氧化钇的引入有显着的效果。电子结构指纹，其特征在于每个阶段从他们的电子光谱被识别。我们已经进行了电子能量损失谱实验在低动量转移和比较这些结果的理论谱内计算的无规相位近似。我们显示的依赖性的价和4p（N-2，N-3边缘）等离子体激元的晶体结构，后者的依赖性被带到光谱的局部场效应。最后，我们属性的低能激发在EELS中观察到的m-ZrO 2的缺陷态2 eV以上的本征价带的顶部，和EELS的基本带隙值与5.2或5.8 eV的真空紫外光谱确定的间隙是调和。
The atomic and electronic structures of zirconia are calculated within density functional theory, and their evolution is analyzed as the crystal-field symmetry changes from tetrahedral [cubic (c-ZrO2) and tetragonal (t-ZrO2) phases] to octahedral (hypothetical rutile ZrO2), to a mixing of these symmetries (monoclinic phase, m-ZrO2). We find that the theoretical bulk modulus in c-ZrO2 is 30% larger than the experimental value, showing that the introduction of yttria in zirconia has a significant effect. Electronic structure fingerprints which characterize each phase from their electronic spectra are identified. We have carried out electron energy-loss spectroscopy experiments at low momentum transfer and compared these results to the theoretical spectra calculated within the random phase approximation. We show a dependence of the valence and 4p (N-2,N-3 edge) plasmons on the crystal structure, the dependence of the latter being brought into the spectra by local-field effects. Last, we attribute low energy excitations observed in EELS of m-ZrO2 to defect states 2 eV above the top of the intrinsic valence band, and the EELS fundamental band gap value is reconciled with the 5.2 or 5.8 eV gaps determined by vacuum ultraviolet spectroscopy.