首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到18条相似文献,搜索用时 140 毫秒
1.
SrHfO3和SrTiO3光学特性的第一性原理研究   总被引:1,自引:0,他引:1       下载免费PDF全文
用全电势线性缀加平面波法(FLAPW)计算了SrTiO3和SrHfO3的光学特性,即介电函数虚部ε2(ω)、光学吸收系数I(ω)和反射率R(ω).对它们光学特性进行了对比分析,给出了它们光学特性的差别,并进行了解释.计算的SrTiO3光学谱分别在4.4,7.4,8.3和23.6eV处出现峰值,且其在4.4eV处的峰值比较高而尖.计算结果与实验值符合得很好.  相似文献   

2.
N掺杂锐钛矿TiO2光学性能的第一性原理研究   总被引:1,自引:0,他引:1       下载免费PDF全文
彭丽萍  徐凌  尹建武 《物理学报》2007,56(3):1585-1589
用平面波赝势方法(PWP)计算了N掺杂锐钛矿型TiO2前后的光学特性,即介电函数虚部ε2(ω),光学吸收系数I(ω)和反射率R(ω). 并从能带结构上解释了为什么掺N后锐钛矿型TiO2的光学谱在2.93,3.56和3.97eV处相对掺杂前会出现3个峰值的原因. 从光谱图上分析得出,掺杂后TiO2要发生红移现象,实验现象证实了这一结果. 关键词: N掺杂 2')" href="#">锐钛矿型TiO2 光学性能 第一性原理  相似文献   

3.
用全电势线性缀加平面波法(FLAPW)计算了KTa0.5Nb0.5O3四方相和立方相 的光学特性,即介电函数虚部ε2(ω)、光学吸收系数I(ω)和反射率R(ω). 在四方相,介电虚部沿a,b轴,在3,7和23eV附近,分别有三个介电峰.沿c轴的三个介电峰分别位于4,8和23eV.其中4eV附近的介电峰非常尖锐而且高.从8至18eV,沿a,b ,c轴三个方向都有许多低的介电峰.通过对两相光学特性的对比分析发现铁电相KTa0.5Nb0.5O3具有更强的各向异性. 关键词: 平面波法计算 光学常量和参数 铁电体  相似文献   

4.
姜平  司道伟  朱晖文  李培刚  王顺利  崔灿  唐为华 《物理学报》2011,60(11):117203-117203
采用射频磁控溅射方法在(001)SrTiO3衬底上制备(001)取向的(BiFeO3)25/(La0.7Sr0.3MnO3)25多层膜.光学测试结果表明,1.3-2.1 eV范围内,相对于衬底而言多层膜光吸收增强; BiFeO3的带隙为2.7 eV. 另外,结合绝缘介质导电模型分析了所测得的电流-电压数据,在所测试的温度及电压下,所制备的(BiFeO3)25/(La0.7Sr0.3MnO3)25多层膜的导电机理由空间电荷限制电导主导. 关键词: 多层膜 吸光度 空间电荷限制电导  相似文献   

5.
用最小偏向角法在20℃下精确测量了0.62Pb(Mg1/3Nb2/3)O3< /sub>-0.38PbTiO3( 0.62PMN-0.38PT)单晶的折射率,给出了该温度下折射率色散的Sellmeier方程.研究了能带 结构与折射率的关系,计算了样品的Sellmeier光学系数:对no,E0=5.50eV,λ0=0.2 26μm,S=1.004×1014m-2,Ed=28.1 0eV;对ne,E0=5.57eV,λ 0=0.223μm,S0=1.017×1014m-2,Ed=28.10eV.A BO3型钙钛矿材料中,BO6八面体基元决定了晶体的能带结构,对折 射率产生重要影响. 关键词: PMNT单晶 折射率 Sellmeier光学系数  相似文献   

6.
邓娇娇  刘波  顾牡 《物理学报》2013,62(6):63101-063101
采用基于第一性原理的赝势和平面波方法计算了新型闪烁晶体基质材料 LuI3的结构特性和电子特性. 计算结果表明: -4.4 eV附近有一个宽度约为0.2 eV的窄带, 主要是Lu的4f态; -3.55–0 eV之间的态组成了价带, 这主要是I的5p态; 2.44–12.35 eV之间的态组成了LuI3的导带, 这主要来源于Lu的5d态, 其中还含有少量的Lu的6s态的贡献. 在-3.46 eV处, Lu的6s态、4f态和I的5p态同时出现了尖峰, 说明相邻的Lu原子的6s态, 4f态与I原子的5p态之间的相互作用强, 出现了杂化峰. 估算出LuI3晶体的理论光产额约为100000 ph/MeV, 主要得益于LuI3合适的带隙和能带结构. 关键词: 3')" href="#">LuI3 第一性原理 电子结构  相似文献   

7.
使用QUANTUM ESPRESSO(QE)软件包实现的密度泛函理论研究了Si, Ge, Zr和Sn掺杂SrTiO3的结构,电子结构和光催化性能.使用广义梯度近似(GGA)获得SrTiO3的晶格常数与先前的实验数据非常一致.同时,获得了SrTi0.875X0.125O3(X=Si, Ge, Zr, Sn)四种掺杂体系的晶格常数. SrTiO3和SrTi0.875X0.125O3(X=Si, Ge, Zr, Sn)四种掺杂的带隙值分别1.853 eV、1.849 eV、1.916 eV、1.895 eV和1.925 eV.在研究五种SrTiO3体系的光催化性能时,采用剪刀算符对五种SrTiO3体系的带隙值进行修正.计算本征SrTiO3和SrTi0.875X0.125O3  相似文献   

8.
沈杰  魏宾  周静  Shen Shirley Zhiqi  薛广杰  刘韩星  陈文 《物理学报》2015,64(21):217801-217801
Ba(Mg1/3Nb2/3)O3 (BMN)复合钙钛矿陶瓷具有高介电常数和高品质因子等介电性能, 预示了其在光学领域的应用前景. 本文采用第一性原理方法计算了BMN的电子结构, 对其本征光学性能进行分析和预测. 对固相合成六方相BMN的XRD 测试结果进行Rietveld精修(加权方差因子Rwp=6.73%, 方差因子Rp=5.05%), 在此基础上建立晶体结构模型并对其进行几何优化. 运用基于密度泛函理论(DFT)的平面波赝势方法, 对六方相BMN晶体模型的能带、态密度和光学性质进行理论计算. 结果表明BMN的能带结构为间接带隙, 禁带宽度Eg=2.728 eV. Mg-O和Ba-O以离子键结合为主, Nb-O以共价键结合为主, 费米面附近的能带主要由O-2p和Nb-4d 态电子占据, 形成了d-p轨道杂化. 修正带隙后, 计算了BMN沿[100]和[001]方向上的复介电函数、吸收系数和反射率等光学性质. 结果表明, BMN近乎光学各向同性, 在可见光区, 其本征透过率为77%< T <83%, 折射率为1.91< n <2.14, 并伴随一定的色散现象. 实验测试结果与理论计算结果相吻合.  相似文献   

9.
房丽敏 《物理学报》2011,60(5):56801-056801
采用基于密度泛函理论的第一性原理平面波赝势方法研究了SrTiO3(001)表面上Au和N原子间相互作用的微观机理.通过比较分析N置换表面层O原子前后SrTiO3(001)表面吸附Au原子体系的相关能量和电子结构,发现SrTiO3(001)表面吸附Au原子和N替代表面层O原子的置换过程二者之间存在明显的"协同效应",即N原子置换SrTiO3(001)表面层O原子的过程增强了相应表面吸附Au原子的稳定性,而SrTiO关键词: 表面结构 相互作用 第一性原理  相似文献   

10.
邱安宁  张澜庭  吴建生 《物理学报》2007,56(8):4891-4895
基于第一性原理全势线性缀加平面波方法和局域密度近似(LDA),对ReSi1.75的基态晶格属性进行了研究. 结构优化的结果表明,ReSi1.75的基态平衡晶格常数比实验值小约0.6%. 在LDA计算基础上,考虑局域的Re的d电子库仑作用,用LDA+U方法计算了ReSi1.75的电子结构,发现当Ueff=U-J=4.4eV时,能带结构呈半导体性质. 具有0.12eV 关键词: 1.75')" href="#">ReSi1.75 局域密度近似 自相互修正作用 电子结构  相似文献   

11.
We present first-principles VASP calculations of the structural, electronic, vibrational, and optical properties of paraelectric SrTiO3 and KTaO3. The ab initio calculations are performed in the framework of density functional theory with different exchange-correlation potentials. Our calculated lattice parameters, elastic constants, and vibrational frequencies are found to be in good agreement with the available experimental values. Then, the bandstructures are calculated with the GW approximation, and the corresponding band gap is used to obtain the optical properties of SrTiO3 and KTaO3.  相似文献   

12.
焦照勇  郭永亮  牛毅君  张现周 《物理学报》2013,62(7):73101-073101
采用基于密度泛函理论(DFT)的第一性原理超软赝势方法对缺陷黄铜矿结构XGa2S4 (X=Zn, Cd, Hg)晶体的晶格结构、电学以及光学性质进行了对比研究. 分析比较了它们的晶格常数、键长、能带结构、态密度、介电函数、折射率和反射系数等性质, 并总结其变化趋势. 结果表明: 这三种材料的光学性质在中间能量区域(4 eV–10 eV)表现出较强的各向异性, 而在低能区域(<4 eV)和高能区域(>10 eV)各向异性较弱. ZnGa2S4和HgGa2S4两种材料的折射率曲线在等离子体频率ωp处有一明显的拐点, 反射系数在ωp处达到最大值后急剧下降. 三种晶体的强反射峰均处于紫外区域, 因此可以用作紫外光屏蔽或紫外探测材料. 关键词: 缺陷黄铜矿结构 电子结构 光学性质 第一性原理计算  相似文献   

13.
Structural, elastic and mechanical properties of orthorhombic SrHfO3 under pressure have been investigated using the plane-wave ultrasoft pseudopotential technique based on the first-principles density functional theory. The calculated equilibrium lattice parameters and elastic constants of orthorhombic SrHfO3 at zero pressure are in good agreement with the available experimental and calculational values. The lattice parameters, total enthalpy, elastic constants and mechanical stability of orthorhombic SrHfO3 as a function of pressure were studied. With the increasing pressure, the lattice parameters and volume of orthorhombic SrHfO3 decrease whereas the total enthalpy increases. Orthorhombic SrHfO3 is mechanically stable with low pressure (<52.9 GPa) whereas that is mechanically instable with high pressure (>52.9 GPa). The bulk modulus, shear modulus, Young's modulus and mechanical anisotropy of orthorhombic SrHfO3 as a function of pressure were analyzed. It is found that orthorhombic SrHfO3 under pressure has larger bulk modulus, better ductility and less mechanical anisotropy than orthorhombic SrHfO3 at 0 GPa.  相似文献   

14.
We investigated the high-energy electronic structure of a 5d perovskite SrHfO3 by using optical spectroscopy and O 1s x-ray absorption spectroscopy. From the combined spectra the values of electronic structure parameters are estimated properly. In particular, the crystal field splitting energy, which is closely associated with the p–d hybridization strength, is as high as ~5 eV, and the Sr 4d bands appear to be strongly mixed with the Hf 5d bands. These findings are discussed in relation to a possible ferroelectric instability in SrHfO3, and are compared with electronic properties of similar compounds, 3d SrTiO3 and 4d SrZrO3.  相似文献   

15.
Structural and electronic properties of Fe-doped BaTiO3 and SrTiO3   总被引:1,自引:0,他引:1       下载免费PDF全文
张超  王春雷  李吉超  杨鲲 《中国物理》2007,16(5):1422-1428
We have performed first principles calculations of Fe-doped BaTiO3 and SrTiO3. Dopant formation energy, structure distortion, band structure and density of states have been computed. The dopant formation energy is found to be 6.8eV and 6.5eV for Fe-doped BaTiO3 and SrTiO3 respectively. The distances between Fe impurity and its nearest O atoms and between Fe atom and Ba or Sr atoms are smaller than those of the corresponding undoped bulk systems. The Fe defect energy band is obtained, which mainly originates from Fe 3d electrons. The band gap is still an indirect one after Fe doping for both BaTiO3 and SrWiO3, but the gap changes from Γ-R point to Γ-X point.  相似文献   

16.
We present structural, elastic, electronic and optical properties of the perovskites SrMO3 (M=Ti, and Sn) for different pressure. The computational method is based on the pseudo-potential plane wave method (PP-PW). The exchange-correlation energy is described in the generalized gradient approximation (GGA). The calculated equilibrium lattice parameters are in reasonable agreement with the available experimental data. This work shows that the perovskites SrTiO3, and SrSnO3 are mechanically stable and present an indirect band gaps at the Fermi level. Applied pressure does not change the shape of the total valence electronic charge density and most of the electronic charge density is shifted toward O atom. Furthermore, in order to understand the optical properties of SrMO3, the dielectric function, absorption coefficient, optical reflectivity, refractive index, extinction coefficient and electron energy-loss are calculated for radiation up to 80 eV. The enhancement of pressure decreases the dielectric function and refractive indices of SrTiO3 and SrSnO3.  相似文献   

17.
Electronic structure and optical properties of SrHfO3 are calculated using the full potential linearized augmented plane wave plus local orbitals method. The calculated equilibrium lattice is in reasonable agreement with the experimental data. From the density of states (DOS) as well as charge density studies, we find that the bonding between Sr and HfO3 is mainly ionic and that HfO3 entities bond covalently. The complex dielectric functions are calculated, which are in good agreement with the available experimental results. The effect of the spin-orbit coupling on the optical properties is also investigated and found to be quite small.  相似文献   

18.
Well-crystallized 250 nm-thick SrTiO3 thin films on fused-quartz substrate were prepared by pulsed laser deposition. The band-gap of SrTiO3 thin film by transmittance spectra is equal to 3.50 eV, larger than 3.22 eV for the bulk crystal. The nonlinear optical properties of the films were examined with picosecond pulses at 1.064 μm excitation. A large two-photon absorption (TPA) with absorption coefficient of 87.7 cm/GW was obtained, larger than 51.7 cm/GW for BaTiO3 thin films. The nonlinear refractive index n2 is equal to 5.7×10−10 esu with a negative sign, larger than 0.267×10−11 esu for bulk SrTiO3. The large TPA is attributed to intermediate energy levels introduced by the grain boundaries, and the optical limiting behaviors stemming from both TPA and negative nonlinear refraction were also discussed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号