共查询到20条相似文献，搜索用时 15 毫秒
1.
《自然科学进展(英文版)》2019,29(2):119-123
Neodymium substituted Li_2MnO_3 samples were prepared by the solid-state reaction method. The crystal and electronic structure properties of the prepared samples were investigated by x-ray based techniques. According to the analysis, it was determined that Nd atoms did not sit in to the Cr coordinations in Nd substituted samples and built up a different crystal structure. To support the analysis of the crystal structure study of the samples,electronic structure properties of the Nd substituted samples were studied via the collected data by x-ray absorption fine structure(XAFS) spectroscopy from the Mn K-edge. The results of the data analysis revealed that due to the misfit with the ionic radii and also the oxidation states, substituted neodymium atoms built up isolated crystal domains in Li_8Mn_5Nd_(18) O_(39) cubic crystal structure. The symmetry in Mn K-edge absorption data of the sample both in parent Li_2MnO_3 and Nd substituted samples confirmed that Mn coordinations has not been influenced by the Nd substitution. 相似文献
2.
利用X射线吸收精细结构(XAFS)和X射线衍射(XRD)研究了化学还原法制备的不同磷含量的Ni_(100-x)P_x合金的原子和电子结构.结果表明,当x=10时,磷元素的掺入导致了NiP样品中fcc结构的镍晶格扭曲和膨胀,Ni-Ni第一近邻配位的键长约增加0.03 A.随着磷含量的增加,膨胀和扭曲加剧,当x达到14左右时,样品的fcc-Ni晶格被完全破坏,从而形成非晶态NiP合金.X射线吸收近边结构(XANES)的结果表明,低磷含量(x≤10)时NiP样品的电子结构没有明显的变化,随着磷含量的增加,Ni4p态的分布变得宽化和越来越弥散.而当x达到26时,有大量电荷从Ni原子转移到P原子. 相似文献
3.
4.
Alexander V. Kolobov a) onleavefromA .F .IoffePhysico TechnicalInstitute StPetersburg Russia 《中国科学技术大学学报》2001,31(3):282-288
Ｔｈｅｌａｔｔｉｃｅｍｉｓｍａｔｃｈｂｅｔｗｅｅｎｔｈｅｓｕｂｓｔｒａｔｅａｎｄｔｈｅｏｖｅｒｇｒｏｗｎｌａｙｅｒａｌｌｏｗｓｔｈｅｆｏｒｍａｔｉｏｎｏｆｓｅｌｆ ａｓ ｓｅｍｂｌｅｄｑｕａｎｔｕｍｄｏｔｓ (ＱＤｓ)ｔｈｒｏｕｇｈｔｈｅＳｔｒａｎｓｋｉ Ｋｒａｓｔａｎｏｖｍｅｃｈａｎｉｓｍ[1,2 ] .Ｔｈｉｓｔｅｃｈｎｉｑｕｅｈａｓｂｅｅｎｓｕｃｃｅｓｓｆｕｌｌｙａｐｐｌｉｅｄｔｏｖａｒｉｏｕｓｓｅｍｉｃｏｎｄｕｃｔｏｒｓｙｓｔｅｍｓ,ａｎｄｉｎｐａｒｔｉｃｕｌａｒｔｏＧｅ/Ｓｉｑｕａｎｔｕｍｄｏｔｓ(Ｑ… 相似文献
5.
采用机械合金化MA(mechanical alloying)方法成功地制备了Al70Cu20Fe10纳米合金.在结构分析中,联合使用传统的XRD(X-ray diffraction)方法与新兴的XAFS(X-ray absorption fine structures)技术,使XRD的长程有序结构和XAFS的特定原子近邻环境两个方面的信息相互补充、互为印证,有效地克服了高度无序体系结构分析的困难.结果表明,机械合金化Al70Cu20Fe10(MA-10 h)合金中的化合物成分是体心四方结构的Al2Cu,Al70Cu20Fe10(MA-20 h和MA-40 h)合金中的化合物成分是简单立方结构的Cu9Al4. 相似文献
6.
化学法制备纳米氧化物及其EXAFS特征 总被引：3，自引：0，他引：3
利用化学方法合成了纳米Ｙ２Ｏ３和纳米ＺｒＯ２颗粒（晶粒的平均大小为２５ｎｍ和１４ｎｍ）,并制得了相应氧化物的纳米压结块。探讨了纳米氧化物颗粒被压结成型的各种影响因素。对不同成型压力及不同尺寸纳米氧化物的ＥＸＡＦＳ（扩展Ｘ射线吸收精细结构）谱特征进行了,工与纳米金属的ＥＸＡＦＳ谱特征进行了比较。结果表明,纳米氧化物块体中,晶界原子主要由氧原子组成。 相似文献
7.
X-ray absorption fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS) were combined to study the effect of (Cr, Cu, Li) codopants on the distribution of magnetic Co atoms in Co-doped ZnO thin films. For the single-doping of Co in ZnO, there are two occupation sites of Co in ZnO: the substitutional sites for Zn and metallic Co clusters. After Cr doping, the metallic Co clusters vanish and all the Co atoms occupy the substitutional sites. On the contrary, Cu(Li)-codoping further increases the content of metallic Co clusters. In-depth analysis suggests that the distinct roles of Cr and Cu(Li) codopants for mediating the distribution of Co atoms in ZnO are intimately related to the occupation sites of codopants. 相似文献
8.
Pichitchai Butnoi Wipada Senanon Narong Chanlek Yingyot Poo-arporn Supree Pinitsoontorn Santi Maensiri Prayoon Songsiriritthigul Pongtanawat Khemthong Pinit Kidkhunthod 《自然科学进展(英文版)》2021,31(3):420-427
1-x(Li2 O-2 P2 O5)-xMnO2 glasses where x=0.2,0.3 and 0.4 mol%,respectively,were synthesized by meltedquenching method.The Mn and P oxidation states and local structures around Mn and P-ions including Mn-O and P-O bonding distances and coordination numbers have been studied via X-ray absorption near edge structure(XANES) and extended X-ray absorption fine structure(EXAFS),respectively.XANES results exhibit a coexistence of oxidation state of Mn2+ 相似文献
9.
Taher Yousefi Reza Davarkhah Ahmad Nozad Golikan Mohammad HosseinMashhadizadeh Ahmad Abhari 《自然科学进展(英文版)》2013,23(1):51-54
Fe2O3 nano-particles have been synthesized by simple cathodic electrodeposition from the low-temperature nitrate bath.The morphology and crystal structure of the obtained oxide powder were analyzed by means of scanning and transmission microscopy(SEM and TEM),X-ray diffraction(XRD) and Fourier transform infrared(FTIR) spectroscopy.Thermal behavior and phase transformation during the heat treatment of as-deposited sample were investigated by differential scanning calorimetry(DSC) and thermogramimetric analysis(TGA).The results showed that the deposited Fe2O3 was composed of the nanoparticles with grain size of approximately 10-60 nm.A serious problem during cathodic electrodeposition of iron oxide was splashing of deposit into electrolyte due to its low adhesion.This problem was tackled by reducing the bath temperature and dielectric constant of solvent. 相似文献
10.
利用X 射线近边吸收谱学(X-ray Absorption Near Edge Structure, XANES)方法研究了不同浓度的FeCl3 水溶液中Fe3+离子的电子结构和近邻结构. 在不同浓度的FeCl3 水溶液的XANES 谱中, XANES 谱的形状随着FeCl3 浓度的不同而发生改变. 在XANES 谱的边前结构中观测到边前锋的分裂, 其分裂的能量差约为1.6 eV, 随着浓度的降低约有0.2 eV 的高能方向的位移, 此边前结构由1s-3d 轨道的电子跃迁引起, 双峰分裂来源于配位体配位引起的3d 轨道分裂. 随着FeCl3 浓度的改变, XANES 谱的主峰也发生变化, 此变化来源于溶液中Fe—Cl 配位与Fe—O 配位的比例变化. 另外, 利用量子化学计算的方法对于Fe3+与不同数目的H2O 和Cl?配位体络合时的构型进行了计算, 得到了Fe3+在水溶液中近邻结构的信息, 从另一方面解释了FeCl3 溶液中Fe3+离子3d 轨道分裂能的变化 相似文献
11.
锂离子电池正极材料LiNixCo1 - xO2局域结构的研究 总被引：4，自引：0，他引：4
对合成制备的LiNixCo1 - xO2正极材料及其稀土金属Ce元素添加改性的正极材料进行了X射线衍射(XRD)和扩展X射线吸收精细结构(EXAFS)表征.结果表明,随着焙烧温度的升高,物相组成趋于单一,晶格趋向完整,800 ℃时完全形成LiNiO2、LiCoO2晶相结构.LiNixCo1 - xO2样品中Ni/Co摩尔比不影响LiNiO2晶相的形成,而只影响其晶相组成;掺杂的稀土金属Ce元素以CeO2状态存在于产物中,CeO2对LiNiO2晶相形成有一定的影响;LiCoO2的焙烧温度不能大于900 ℃,否则Co被氧化为Co3O4;样品中Ni与Co原子的局域结构,除Ni与Co原子相互影响外,掺杂Ce后对它们的局域结构也有较大影响. 相似文献
12.
利用XRD(X射线衍射)和XAFS(X射线吸收精细结构),研究了机械合金化Fe60Ni40二元金属合金的微结构随球磨时间的变化情况．结果表明：球磨5h,α-Fe和金属Ni的混合物开始形成合金,样品保持原来的bcc和fcc结构;球磨20h,α-Fe的特征配位峰完全消失,样品为比较均匀的fcc结构的固溶体;球磨时间增至40h时,Fe原子的近邻结构又有了新的变化,是由多种物态组成的复相固溶体．用柯西公式计算的结果表明：随着球磨时间的增加,晶粒不断细化,晶格畸变加剧,Ni相的晶格常数与Fe60Ni40合金的物相同步变化．这说明机械合金化过程中,晶格畸变引起的晶格常数的变化是相变的重要因素． 相似文献
13.
为了简化三烷基氧磷(TRPO)流程,合成了一种新型反萃剂N,N’-二甲基-3-氧杂-戊酰胺酸(DOGA);运用红外吸收光谱(IR)、质谱(M S)、扩展X射线吸收精细结构光谱(EXAFS)技术研究了DOGA与N d(Ⅲ)、F e(Ⅲ)、Z r(Ⅳ)的配位物结构,解释了DOGA的配位性能。研究结果表明:DOGA属于桥式四齿型配位体,参加配位的都是O原子;DOGA与N d(Ⅲ)、F e(Ⅲ)、Z r(Ⅳ)主要生成配位比为3的配合物,第一配位层配位数分别为6、7.7、6.5,第二配位层配位数分别为2.4、2.5、2.2;DOGA与F e(Ⅲ)生成的配合物中有1~2个H2O参加配位。DOGA与N d(Ⅲ)、F e(Ⅲ)、Z r(Ⅳ)能形成聚合物形式的配合物,DOGA能有效地从TRPO中反萃N d(Ⅲ)、F e(Ⅲ)、Z r(Ⅳ),能简化TRPO流程。 相似文献
14.
本文对[Ge(TPP)I_2]的Ge K吸收边做了EXAFS谱.在最小二乘曲线拟合的基础上,提出了使用ΔR与ΔE_0之间的线性关系,对核间距进行精细调整的技术.同时提出,用N=B/Sj,Sj=S_1~2(1-15σ)的经验公式,对配位数做精细调整.得到第一配住层GeN的核间距R=0.202nm,配位数N=3.7; 第二配位层Ge-1的核间距R=0.249nm,配位数N=1.8.该化合物的分子应为四方双锥的构型. 相似文献
15.
16.
讨论了利用XANES谱研究凝聚态物质费米能附近空态电子结构的要点,给出了XANESD谱多次散射计算的概要,并列举了探测凝取态物质电子结构的XANES谱学方法的几个实例。 相似文献
17.
Dichloro-diglycine zinc II(DCDGZ II),a semi-organic nonlinear optical material has been synthesized and single crystals were grown from the aqueous solution up to dimensions 20×10×3 mm3.The title compound,DCDGZ II(C4H10Cl2N2O4Zn H2O) crystallizes into monoclinic structure with the space group of C2/c.The unit-cell parameters were found to be a=14.4191(7),b=6.9180(2),c=12.9452(6) and Z=4.In the crystal structure,DCDGZ II layer is building up alternatingly with layers of water in which the zinc ions lie on a twofold axis.Theoretical calculations for polarizability,which are useful for device fabrication were made using Clausius–Mosotti equation and Penn analysis and the results were compared.Fourier transform infrared(FTIR) spectroscopic studies were performed for the identification of the different functional groups presented in the compound.The UV–vis–NIR absorption spectrum reveals that the lower UV cut-off wavelength is 240 nm.The optical band gap of the crystal was estimated as 2.2 eV.The surface morphology,thermal behaviour,dielectric properties have been studied using SEM,TG/DTA and LCR HITESTER analyzer.The nonlinear optical property of the crystal was also confirmed using Kurtz powder technique. 相似文献
18.
利用ＥＸＡＦＳ结合ＩＲ等技术对５种含钨原子的多核原子簇的结构进行了研究．提出了一种在原子簇中的吸收原子有不同配位环境时的处理方法．依据表观配位数Ｎｊ′与原子簇中吸收原子总数的乘积即为各种吸收原子数与它真实的配位数Ｎｐｊ乘积之和的原则进行处理．用此法处理了２个样品 相似文献
19.
20.
A study on tuning the fluorescence property of Cu nanoclusters by thiol ligands was presented. The photoluminescence (PL) measurements show that the luminescent wave-length of Cu nanoclusters capped by 2-mercapto-5-n-propylpyrimidine (MPP) is gradually blue-shifted from 623 nm to 584 nm, with increasing concentrations of dodecanethiol (C12SH) added into the solution. The added thiol ligands, as suggested by mass spectra, do not change the number of Cu atoms in the clusters, but replace some of the original MPP ligands. X-ray absorption fine structure (XAFS) spectra reveal that with the increment of C12SH ligands, the Cu—Cu bonds disappear, the Cu—S bond length is contracted from the original 0228 nm to 0.224 nm, and the charge transfer from Cu to S is enhanced. Moreover, the etching effect of C12SH ligands leads to the change of atomic configuration of the Cu cores from the tetrahedron-alike structure to the chain-like structure of —S—Cu—S—. As a result, the electronic features of the Cu clusters show a metallic-to-covalent transition, resulting in the blue-shift of the luminescence and optical absorption wavelengths. 相似文献