Syntheses and Single-crystal Structures of Er3GexGeS7 （1/4≤x≤ 1/2）

As part of our systematic research on the acentric rare earth chalcogenides, the ErAlGeS5/KBr, Er3AgGeS7/KBr and Er6Ge3S14/KBr systems were investigated and three compounds belonging to the R6B2C2Q14 （R = rare earth, B = 6-coordinated element, C = 4-coordinated element, Q = S and Se） family were identified. These compounds crystallize in the P63 space group, and the crystal data are as follows： Er3Ge1/4GeS7, a = 9.6480（14）, c = 5.7920（12） A^°, Z = 2; Er3Ge0.382（8）GeS7, a = 9.6360（14）, c = 5.8460（12） A^°, Z = 2; Er3Ge1/2GeS7, a = 9.6061（13）, c = 5.8346（18）A^°, Z = 2. Single-crystal analysis indicated that the Er3GexGeS7 （x = 1/4, 0.382（8）, 1/2） structures consist of three types of building blocks： ErS7, GeS4 and GeS6 units. Er3MxGeS7 are deficient compounds with the B sites occupied partly by Ge（Ⅳ） and/or Ge（Ⅱ）.     

Pb1-xTbxTi1-xMnxO3(O≤x≤0.10)固溶体的合成、结构与表征

用固相反应合成了Pb1-xTbxTi1-xMnxO3(0≤x≤0.10)固溶体,并用X射线粉末衍射进行了表征,室温下其空间群为P4mm.热分析仪测试结果显示,随着Tb和Mn掺杂量的增加,该固溶体的相变温度Tc降低.介电常数在Tc附近出现峰值,表明对应的相变是铁电相变.磁性测量显示,当x=0.08和x=0.10时,Pb1-xTbxTi1-xMnxO3分别在25和29 K附近有顺磁性向反铁磁性的转变.     

Nonstoichiometry and structural intergrowth in the CaFexMn1−xO3−y (0 ≤ x ≤ 1) system

An electron diffraction and microscopy study of the CaFe_xMn_1−xO_3−y system treated at 1100°C in air has been performed. An increase of y is accompanied by an increase of the cubic perovskite substructure parameter, the nonstoichiometry being accommodated in several ways. The system contains two solid solutions of the perovskite-type (P) and of the brownmillerite-type (B) and also an intermediate phase (x = 0.6) which makes disordered intergrowth with the B-type solid solution. These results are discussed in terms of multitwinning, randomly dispersed oxygen deficiency, and ordered and disordered intergrowth formation.     

La_(1-x)Nd_xCrO_3(0.0≤x≤1.0)的化学键参数计算

使用复杂晶体化学键理论计算了La1-xNdxCrO3 (x =0 .0 ,0 .2 ,0 .4,0 .6 ,0 .8,1.0 )的化学键参数 ,如键性、键极化率等。结果表明 ,La-O ,Nd -O和Cr-O键的共价性基本上不随Nd掺杂的变化而变化 ,这个结论与实验结果一致。键极化率和磁距则随着掺杂量的增加而增加。共价性的大小次序为La -O 相似文献   

HNO与(HF)1≤n≤3分子间的蓝移与红移氢键

运用量子化学从头算方法研究了HNO与分子簇(HF)1≤n≤移氢键, 重极化与重杂化和分子内超共轭导致了氢键的蓝移; 所有的X…H—F(X=O, N, F)氢键都是红移的, 分子间超共轭导致了氢键的红移. 在多分子体系形成的氢键链中, 分子间超共轭作用呈现规律性递变, 它导致了氢键强度与频率位移的规律性变化, 电子密度拓扑分析结果反映和支持了这种规律性变化.     

HNO与（HF）1≤n≤3分子间的蓝移与红移氢键

运用量子化学从头算方法研究了HNO与分子簇(HF)1≤n≤3形成的蓝移与红移氢键.在这些体系中,F…H-N都是蓝移氢键,重极化与重杂化和分子内超共轭导敛了氰键的蓝移;所有的X…H-F(X=O,N,F)氢键都是红移的,分子问超共轭导致了氢键的红移.在多分子体系形成的氢键链中,分子问超共轭作用呈现规律性递变,它导致了氢键强度与频率位移的规律性变化,电子密度拓扑分析结果反映和支持了这种规律性变化.     

YPxV1—xO4（0≤x≤1）：Dy^3＋的合成及其光谱性质的研究

本文报道了不同组成的ＹＰｘＶ１－ｘＯ４（０≤ｘ≤１）：Ｄｙ＾３＋的合成和结构。ＹＰｘＶ１－ｘＯ４（０≤ｘ≤１）为四方晶系，晶胞参数随ｘ的增大呈线性减小。基质的Ｓｔｏｋｅｓ位移随ｘ的增大逐渐变大，而激发光谱峰值则向短波方向移动。在ＹＰｘＶ１－ｘＯ４：０．００６Ｄｙ＾３＋体系中，ｘ＞０．４时出现的基质发射是由ＰＯ＾３－４引起的。基质及Ｄｙ＾３＋的发光效率和Ｄｙ＾３＋的发光强度的黄蓝比均与ｘ有关。同时探     

La0.67Sr0.33Mn1-xCrxO3(0.00≤x≤0.30)的特殊输运行为

研究了La0.67Sr0.33Mn1-xCrxO3(0.00≤x≤0.30)体系的M-T曲线、ρ-T曲线和MR-T曲线. 实验结果表明 Cr对Mn位的替代对居里温度TC影响不明显, 但是随着Cr含量的增加, 电阻率和磁电阻出现双峰行为, CMR效应的温区被极大地拓宽了. 体系的特殊输运行为和异常CMR效应可能是Mn3+-O-Mn4+和Mn3+-O-Cr3+两种通道共存和竞争的结果.     

Mg1.75Al0.25Ni1-xCrx (0≤x≤0.2)合金的制备及其性能

用扩散烧结法制备了Mg1.75Al0.25Ni1-xCr（0≤x≤0．2）系列合金,XRD结构分析表明,用Cr部分替代Mg1.75Al0.25Ni中的Ni,合金的晶体结构并不发生改变,主相为具有立方Ti2Ni结构的Mg3AlNi2相,只是其晶格常数α变大,Cr的替代提高了合金的放电容量,经过一个充放电循环后达到最大值。当x为0．1时,有利于提高合金电极的循环稳定性。测试4种合金阳极极化曲线发现,其腐蚀电位由正到负的顺序为Mg1.75Al0.25Ni0.9Cr0.1〉Mg1.75Al0.25Ni〉Mg1.75Al0.25Ni0.8Cr0.2〉Mg2Ni,说明Mg1.75Al0.25Ni0.9Cr0.1合金具有相对较好的抗腐蚀性．该系列合金循环稳定性结果也支持这一结论．用球磨方法改变合金性能,发现合金的相组成和相结构在球磨后均发生了变化,合金不再需要活化过程,但其放电容量并没有得到提高。     

ChemInform Abstract: (Sr1-xBax)FeO2 (0.4 ≤ x ≤ 1): A New Oxygen-Deficient Perovskite Structure.

The new oxygen-deficient perovskites of title are prepared by reaction of (Sr_1-xBa_x)FeO_3-δ (x = 0.4, 0.5, 0.6, 0.7, 0.8, 0.9; δ ≤ 0.5; obtained from stoichiometric mixtures of SrCO₃, BaCO₃, and Fe₂O₃ at 1473 K in air for 48 h) with an excess of CaH₂ at 593 K for 3—14 d (0.4 ≤ x ≤ 0.9) and NaH at 413 K for 3 d (x = 1.0).     

La0.67Sr0.33Mn1-xCrO3（0.00≤x≤0.30）的特殊输运行为

研究了La0.67Sr0.33Mn1-xCrO3(0.00≤x≤0.30)体系的M-T曲线、p-T曲线和MR-T曲线。实验结果表明：Cr对Mn位的替代对居里温度Tc影响不明显，但是随着Cr含量的增加，电阻率和磁电阻出现双峰行为，CMR效应的温区被极大地拓宽了。体系的特殊输运行为和异常CMR效应可能是Mn^3 -O-Mn^4 和Mn^3 -O-Cr^3 两种通道共存和竞争的结果。     

(Sr(1-x)Ba(x))FeO2 (0.4 ≤ x ≤ 1): a new oxygen-deficient perovskite structure

Topochemical reduction of (layered) perovskite iron oxides with metal hydrides has so far yielded stoichiometric compositions with ordered oxygen defects with iron solely in FeO(4) square planar coordination. Using this method, we have successfully obtained a new oxygen-deficient perovskite, (Sr(1-x)Ba(x))FeO(2) (0.4 ≤ x ≤ 1.0), revealing that square planar coordination can coexist with other 3-6-fold coordination geometries. This BaFeO(2) structure is analogous to the LaNiO(2.5) structure in that one-dimensional octahedral chains are linked by planar units, but differs in that one of the octahedral chains contains a significant amount of oxygen vacancies and that all the iron ions are exclusively divalent in the high-spin state. M?ssbauer spectroscopy demonstrates, despite the presence of partial oxygen occupations and structural disorders, that the planar-coordinate Fe(2+) ions are bonded highly covalently, which accounts for the formation of the unique structure. At the same time, a rigid 3D Fe-O-Fe framework contributes to structural stabilization. Powder neutron diffraction measurements revealed a G-type magnetic order with a drastic decrease of the Néel temperature compared to that of SrFeO(2), presumably due to the effect of oxygen disorder/defects. We also performed La substitution at the Ba site and found that the oxygen vacancies act as a flexible sink to accommodate heterovalent doping without changing the Fe oxidation and spin state, demonstrating the robustness of this new structure against cation substitution.     

K X-ray relative transition probabilities for 23≤Z≤33

The K X-ray relative transition probabilities K_b/K_a of some elements for atomic numbers 23Z33 induced by 3 MeV protons were measured. The experimental results are compared with the relativistic Hartree-Fock (RHF) calculations. Good agreements have been obtained considering the experimental error.     

La0.67Sr0.33Mn1-xCrxO3（0．00≤x≤0.30）的特殊输运行为

研究了La0.67Sr0.33Mn1-xCrxO3（0．00≤x≤0.30）体系的M-T曲线、p-T曲线和MR-T曲线。实验结果表明：Cr对Mn位的替代对居里温度Tc影响不明显，但是随着Cr含量的增加，电阻率和磁电阻出现双峰行为,CMR效应的温区被极大地拓宽了。体系的特殊输运行为和异常CMR效应可能是Mn^3＋O-Mn^4＋和Mn^3＋-O-Cr3^3＋两种通道共存和竞争的结果。     

La0.7Mg0.3(Ni1-xCox)3.5 (0≤x≤0.5)储氢合金电化学性能

近年来,具有AB2和AB5复合结构的LaNi3系和La2Ni7系储氢材料由于具有较高的储氢量而引起了人们的关注[1]. 它们可在较温和条件下快速吸放氢, 且理论吸氢量分别为LaNi5的1.25倍及1.11倍.     

固体氧化物燃料电池阳极材料Sm1-xSrxCrO3(0≤x≤0.1)的合成及电化学性能

Sm1-xSrxCrO3;电导率;极化电阻;固体氧化物燃料电池     

Photoelectron imaging of tetrahydrofuran cluster anions (THF)(n) (-) (1≤n≤100)

Anionic tetrahydrofuran clusters (THF)(n) (-) (1≤n≤100) are studied with photoelectron imaging as gas-phase precursors for electrons solvated in THF. Photoelectron spectra of clusters up to n=5 show two peaks, one of which is attributed to a solvated open chain radical anion and the other to the closed THF ring. At n=6, the spectra change shape abruptly, which become more characteristic of (THF)(n) (-) clusters containing solvated electrons. From n=6-100, the vertical detachment energies (VDEs) of these solvated electron clusters increase from 1.96 to 2.71 eV, scaling linearly with n(-1/3). For fully deuterated (THF-d8)(n) (-) clusters, the apparent transition to a solvated electron cluster is delayed to n=11. Extrapolation of the VDEs to infinite cluster size yields a value of 3.10 eV for the bulk photoelectric threshold. The relatively large VDEs at onset and small stabilization with increasing cluster size compared to other solvated electron clusters may reflect the tendency of the bulk solvent to form preexisting voids that can readily solvate a free electron.     

低温燃烧法制备纳米Ce1-xNdxO2-x/2(0≤x≤0.6) 粉体的研究

采用低温燃烧合成工艺，在甘氨酸-硝酸盐体系下制备出纳米Ce1-xNdxO2-x/2(0≤x≤0．6)系列粉体(NDC)。X射线衍射(XRD)结果表明。Nd^3 取代Ce^4 进入晶格内部，形成具有单相立方萤石型结构的固溶体，其晶格常数随Nd^3 掺杂浓度的增大而线性增加，晶粒尺寸在17～28nm之间。透射电镜(TEM)结果表明，粉体尺寸在30-40nm之间，具有较高的烧结活性。拉曼光谱(Rman spectrum)表明％宽化峰与掺杂后固溶体中产生的氧空位有关。     

Phase Evolution and Magnetic Properties of Sn_(1-2x)Fe_xNb_xO_2(0.45≤x≤0.50)

Sn1-2xFexNbxO2(0.45≤x≤0.50) samples were prepared at 1000 ℃ via a simple chemical co-precipitation method.The effects of the concentrations of Sn doped on the structures and magnetic properties of the samples have been investigated.A systematic variation from monoclinic to orthorhombic FeNbO4 structure was observed with increasing Sn content.The phase evolutions were observed from monoclinic structure with x=0.50 to the coexistence of monoclinic and orthorhombic structures with x=0.48,0.47,0.46,and then to orthorhombic structure with x=0.45.Antiferromagnetic behavior was observed for all the samples,and the magnetic ordering temperatures decrease with increasing Sn concentration,which further indicated the sequence of phase transitions.The results suggest that the incorporation of Sn can stabilize the orthorhombic FeNbO4.